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Design Manual 3.01: Plumbing Systems

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2. PDHonline Course M105 5 PDH Plumbing Systems 2012 PDH Online PDH Center 5272 Meadow Estates Drive Fairfax VA 22030 6658 Phone amp Fax 703 988 0088 www PDHonline org www PDHcenter com An Approved Continuing Education Provider Naval Facilities Engineering Command 200 Stovall Street Alexandria Virginia 22332 2300 APPROVED FOR PUBLIC RELEASE Plumbing Systems DESIGN MANUAL 3 01 May 1986 SN0525 LP 300 3030 RECORD OF DOCUMENT CHANGES Instructions DISCARD EXISTING SHEET AND INSERT THIS NEW RECORD OF DOCUMENT CHANGES This is an inventory of all changes made to this design manual Each change is consecutively numbered and each changed page in the design manual includes the date of the change which issued it Change Description Date of Page Number of Change Change Changed 11 ABSTRACT Design criteria for use by qualified engineers is presented for the design of building plumbing systems including above ground and buried sanitary DWV drain waste and vent roof storm drainage and water piping inside and under each building and within 5 feet outside of the building walls Plumbing systems may include buried piping beyond 5 feet outside of the building walls and connections to existing exterior distribution systems 111 PAGE iv INTENTIONALLY BLANK FOREWORD This design manual is one of a series developed from an evaluation of facilities in the shore establishment from sur
3. 03 15 utseg 3 01 67 New Flight Simulator Building Example The data required for this example are essentially the same as used in the office building example The building being designed calls for two lavatories with 2 basins each requiring tepid water and 1 slop sink requiring 120 deg F water The design of the building calls for flow restrictor faucets with 1 2 gallon per minute at the basins and 2 gallons per minute at the slop sink Occupancy water use is the same as in the office building example Groundwater average temperature is 60 deg F with a range of 55 deg 65 deg F The alternative to be considered in design is one storage heater 30 gallons gas heated versus the alternatives calculated in the office building example Natural gas costs 3 67 per 1 000 000 Btu and electricity costs 14 56 The design of new facilities in this example introduces a new cost consideration The point of use water heaters will make it possible to eliminate 120 feet of 314 inch copper pipe from the building construction Annual energy use and cost calculations using the format of calculations from the previous example are summarized below First Alternative Storage Heater Heating energy for lavatories 8 3 x 2 x 25 x 250 120 60 8 300 000 Btu per year 0 75 NOTE If thermostat setting reduced to 95 deg F the annual use would be 4 841 667 Btu Heating energy for slop sink 8 3 x 10 x 250 1
4. 3 01 56 b Automatic 1 3 01 56 11 COST OF ENERGY 3 01 56 a Evaluation 3 01 56 b Example 3 01 56 Metering 3 01 58 d Control 3 01 58 12 RATINGS AND WARRANTIES 3 01 59 a Capacity x s s a c 3 w cx X w Xe w X a x 3 01 59 b Special Problem 3 01 59 APPENDIX A Energy Analysis Example REFERENCHS TS 3o X 97 9e 0 m OX d ke os 3 01 73 FIGURES Figure Title Page 1 Typical Connections to Water Heaters and Hot Water Storage Tanks 3 01 24 2 Air Source Heat Pump 3 01 30 3 Typical WHHP Performance 3 01 31 4 Exhaust Air Heat Pump 3 01 36 5 Water to Water Heat Pump 3 01 37 6 Exhaust Air Heat Source ib 2 3 01 38 7 Solar Water Source Heat Pump 3 01 40 8 Heat Recovery A C System with Auxiliary Condenser of L x lt J 2 DE dE An OO Q 3 01 41 9 Heat Recovery A C System with Desuperheater 3 01 44 10 11 12 13 Table D gt D Typical Solar Systems Cogeneration Heat Recovery Power and Atmospheric Burners Hot Water Energy Cost TABLES Title Sewage Ejector Capacities Rainfall Intensity Based on 10 Frequency 10 Minute Duration Tank Fill Pumps HydroPneumatic Tank High Water Levels and Withdrawals Based on bottom outlet tanks and a 10 percent residual
5. 2301 2101 SSAIIVNHSIIV ONILVAH HO 5 V JIL 3401 71 PAGE 72 INTENTIONALLY BLANK REFERENCES American Society of Heating Refrigerating and Air Conditioning Engineers Inc 1791 Tullie Circle NE Atlanta GA 30329 93 77 Methods of Testing to Determine the Thermal Performance of Solar Collectors 94 77 Methods of Testing Thermal Storage Devices Based on Thermal Performance 95 81 Methods of Testing to Determine the Thermal Performance of Solar Domestic Water Heating Systems ASHRAE Handbook 1982 Applications ASHRAE Handbook 1983 Equipment ASHRAE Handbook 1984 Systems Solar Heating of Domestic and Service Hot Water Manual 1984 Basic Plumbing Code Building Officials and Code Administrators International Inc 4051 West Flossmoor Road Country Club Hills IL 60477 1981 Edition Construction Criteria Manual DOD 4270 1 M Copies may be obtained from the Naval Publications and Forms Center 5801 Tabor Avenue Philadelphia PA 19120 Intermediate Minimum Property Standards Supplement for Solar Heating and Domestic Hot Water Systems 4930 2 Department of Housing and Urban Development Office of Manufactured Housing and Construction Standards 451 7th Street SW Washington DC 20410 1977 with revisions Method to Determine the Heating and Recovery Rate of a WHHP Gas Appliance Manufacturers Association GAMA 1901 North Fort Myer Drive Arlington VA 22209 3 01 73 Methodo
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9. electrical demand determines the generator size If there is excess heat not used by the water heater it can be used to provide space heat if and when needed or be wasted to the atmosphere 3201 53 Engine Exhaust Cool Engine Exhaust Electric Generator ELEM Diesel Engine Heat Pump Hydronic Hot Water Heat Exchanger Plate heat Exchange Domestic Hot Water Return Domestic Hot r 6 D 4 gt Water Supply at Storage Tank FIGURE 11 Cogeneration Heat Recovery 3 01 54 9 POWER BURNERS a Water Heaters The preferred burner for a gas fired water heater is a power burner Comparing manufacturers ratings of power burner and atmospheric burner water heaters of the same size shows that power burner units are at least 5 percent more efficient The higher efficiency results from the ability of a power burner to force the combustion gases through more baffles and tubes than an atmospheric burner which gives more heat transfer surface to work with plus the fire is hotter During the off cycle of a water heater room air passes through the water heater s gas passages and is heated as it passes through to the stack This is a heat loss The additional restrictions offered by baffles and the fan wheel ina power burner unit decrease the convective heat loss as compared to an atmospheric burner unit If water heating load fluctuations cause the burner to be off for lon
10. fifth alternate 352 932 Btu per year 3 01 69 Total annual energy use 3 822 368 1 310 526 352 932 5 485 826 Btu per year 14 56 x 5 485 826 79 87 per year 1 000 000 Fourth Alternative One Half Gallon Tank Heater 3 Heating energy for each lavatory 8 3 x 12 1 2 x 250 95 60 955 592 x 4 3 822 368 Btu per aaa 0 95 Standby loss from Table 2 534 485 Btu per year Slop sink from Alternative 2a 419 737 Btu per year Total annual energy use 822 368 1 534 485 1 419 737 6 776 590 Btu per year 14 56 x 6 776 590 98 67 per year 1 000 000 Water heating costs for this example are summarized in Table A 2 and Life Cycle Costs analysis is displayed in Table A 3 3 01 70 a a n 222014 19 86 00 8 1864 28718 82 98 4 9178 12729 4 0861 UI 503 KBjau3 jenuug 0078101 007166 0076 007041 OO PEEL 007 007998 00 629 3509 12 50 2101 x zd DD GER 00 DER BEE er 007226 007 007102 007222 0Q ZVE 00 SEE 0019 gt uotq3 uuo3 S 00 05 00704 00 0S DD Op P 44 D 72941 AGZ 5 00 99 E zs sasur dde z 00 96 x 00 821 007821 saur idd t 00 091 007051 saaueizydde 0 72913 4011 00 bot 00 v9t PD 2 1 p aseyound 00 261 007251 29
11. tg s o9 ele pue 01 UO 37895 9 01 3 Cu P Traps in Storm Drainage Systems In a combined drainage system the sewer gas from the sanitary system if permitted will flow through the storm drainage system and escape through roof drain and area drains P trap s shall be provided to prevent the escape of this gas into areas where an offensive or hazardous condition would be created The P trap s shall be installed as part of the storm drainage system prior to being combined with the sanitary drainage system 4 VENTING OF THE DRAINAGE SYSTEMS The drainage systems must be vented to protect the traps from being subject to underpressures and overpressures Adequate and economical venting of the system can be achieved by the use of circuit or loop venting to serve groups of fixtures and adjacent fixtures Venting of each fixture should be avoided when one of the above methods of venting can be employed 3 01 10 Section 3 WATER SUPPLY SYSTEMS qi PIPING SYSTEMS a Water Service The water service to each building shall be capable of supplying water at a flow rate and pressure to satisfy the peak requirements In addition to domestic requirements the fire protection and air conditioning requirements if any shall be considered in determining the demands of the facility 1 Excessive
12. 039 watt per m multiplied by C or greater and the following minimum thicknesses 0 5 inch 12 7 mm for nominal pipe diameters up to 1 inch 25 4 mm 1 inch 25 4 mm for nominal pipe diameters of 1 and 1 25 inches 25 4 mm and 38 1 mm respectively 1 5 inches 38 1 mm for nominal pipe diameters of 1 5 and 2 inches 38 1 mm and 50 8 mm respectively and 2 inches 50 8 mm for nominal pipe diameters greater than 2 inches 50 8 mm 1 In a heat recovery system insulate all hot gas refrigerant pipes located outdoors with a minimum 1 inch 25 4 mm thick 0 27 K waterproof insulation 2 MISCELLANEOUS SYSTEMS Insulation may be required for the following plumbing items a Cold Water Where the temperature of the cold water entering a building is below the average normal dew point of the indoor ambient air and where condensate drip will cause damage or create a hazard insulate with a vapor barrier type of insulation to prevent condensation All chilled water piping from a central drinking water cooling system must be insulated with vapor barrier type insulation to prevent condensation b Heating System Where the heat loss from the hot water heating System piping will not beneficially add to the heat required for that space insulate piping the same as in paragraph 1e c Rainwater Conductors To prevent condensation insulate horizontal conductors and roof drains inside the building d Freezing Temperatures Although insulating
13. Correction Factors for Sizing Water Heaters and Auxiliary Equipment Hot Water Demand per Fixture for Various Types of Buildings Estimated Hot Water Demand EE for Various Types of Buildings Water Heater Capacities for One and Two Family Living Units Summary of Water Heater Alternative Summary of Water Heating Alternatives Summary of Life Cycle Costing Inputs Page 3 01 45 3 01 54 3 01 55 3 01 57 3 01 6 3 01 9 3 01 12 3 01 13 3 01 14 3 01 16 3 01 17 3 01 18 3 01 67 3 01 71 3 01 71 Section 1 PLUMBING CRITERIA 1 SCOPE This manual presents criteria pertinent to the design of the following systems within the building and to a distance 5 feet outside of building drainage sanitary and storm water and fuel gases Energy conservation requirements are also included in Section 6 of this manual 2 CANCELLATION This manual on plumbing systems and energy conservation supersedes and cancels NAVFAC DM 3 1 Plumbing Systems of April 1983 3 RELATED CRITERIA Certain criteria related to plumbing systems but not necessarily covered in this manual are found in the following Subject Source Hydrology NAVFAC DM 5 02 Drainage Systems NAVFAC DM 5 03 Water Supply Systems NAVFAC DM 5 07 Domestic Wastewater Control NAVFAC DM 5 08 Industrial and Oily Wastewater Control NAVFAC DM 5 09 Solid Waste Disposal NAVFAC DM 5 10 Hospital and Medical Facilities NAVFAC DM 33 S
14. Example 1 Determine the tank capacity when pump capacity is 150 gallons per minute and tank operating pressure range is 40 to 60 pounds per square inch Referring to Table 4 the withdrawal from the tank is 24 percent of the tank capacity Total tank capacity 2 50 x 150 gpm 568 L min 1 563 gallons 5916 liters 0 24 percent TABLE 4 Hydro Pneumatic Tank High Water Levels and Withdrawals Based on bottom outlet tanks and a 10 percent residual Lore i eo Pressure range High Water Level Withdrawal psi kPa of total tank cap 96 of total tank cap 20 40 140 275 43 33 30 50 205 345 38 28 40 60 275 415 34 24 50 70 345 480 32 22 60 80 415 550 28 18 20 45 140 310 48 38 30 55 205 380 42 32 40 65 275 450 37 27 50 75 345 520 35 25 60 85 415 590 32 22 5 Compressed Air Compressed air is supplied for tank operation according to the tank capacities Satisfactory operation has been attained by providing 1 5 cubic feet per minute cfm for tank capacities up to 500 gallons 1893 L and 2 cfm for capacities from 500 to 3 000 gallons 1 89 to 11 35 mb34 For each additional 3 000 gallons 11 35 mb34 or fraction thereof add 2 cfm 0 0566 mL3J min Quantities are expressed in cubic feet cubic meter per minute free air at pressure equal to the high pressure maintained within the hydro pneumatic tank 6 Controls The controls of a hydro pneumatic syste
15. Subsistence 10 38 20 76 2 15 57 15 57 1 Percent of days use Increase total daily demands by 15 gallons 55 liters per domestic type dishwasher and by 45 gallons 170 liters per clothes washer 3 See NAVFAC DM 33 Series Probable maximum demand 5 147 gal hr 19 480 L x 0 20 1 030 gph 3896 L hr Storage 1 030 x 1 25 1 287 gals 4871 liters Adjustments for 70 deg F incoming water Table 5 1 030 gph x 0 82 845 gph 3198 liters demand 1 287 gal x 0 82 1 056 gal 3997 liters storage Fixtures within kitchen area 1 dishwasher 300 gph 1135 L hr 1 utensil washer 80 gph 303 L hr 2 double pot sinks 60 227 L 120 gph 454 L hr 1 vegetable sink 45 gph 170 L hr TOTAL 545 gph 2062 L hr 545 x 1 0 demand factor 545 gph 2062 L hr demand 545 x 1 0 storage factor 545 gal 2062 Liters storage 20 17 9511 398 LE ZET SE ZET S ZET S 96 92 ZET S 96 92 96 92 46 60 19 ST 19 ST 3001 G ul 549111 186 payeu duaunzoejnuew Jol 8 4 002 491 49 104 55 xue3 ead 3 JO 1 OLE 28 28 ole Z8 osz 99 oc m 052 99 052 99 052 99 052 99 052 99 681 1208746 54 82 SZ 782 GZ 82 SZ 82 SZ 782 SZ 982 SZ 82 SZ 782 SZ S81 6t 3 000
16. WATER SYSTEMS a Water Temperatures Information contained herein for calculating hot water requirements is based on incoming water at 40 deg F 4 4 deg C heated and stored at 140 deg F 60 deg C When incoming water temperature is above 40 deg F 4 4 deg C adjustments shall be made in accordance with Table 5 When hot water at a temperature above 140 deg F 60 deg C is required such as 180 deg F 82 2 deg C for dishwashing it shall be provided by a a booster heater b a separate storage heater for 180 deg F 82 2 deg C water only or c heating and storing all hot water at 140 deg F 60 deg C and utilizing mixing valves to satisfy the demands for 100 deg F to 110 deg F 37 8 deg C to 43 3 deg C water TABLE 5 Correction Factors for Sizing Water Heaters and Auxiliary Equipment Based on hot water being tempered to 110 deg F 43 3 deg C at fixtures 0_ Incoming cold water temperatures deg F deg C Factor L141 40 4 4 1 00 50 10 0 0 96 60 15 6 0 90 70 21 1 0 82 80 26 7 0 71 1 Do not apply when meeting the requirements of kitchen and dishwashing equipment of subsistence buildings laundry washing machines and other similar types of equipment which depend on high temperature water for efficient operation However the heater capacity shall be rated to
17. be increased if the rate of seepage into the sump is more than 50 percent of indicated pump capacities 1 Location Interceptors may be located within or outside of buildings Inside installations Units installed within the building at or near the source of the undesirable ingredient are of a relatively small capacity and are usually the prefabricated type The use of this type of unit eliminates or reduces to a minimum the length of piping between the source and the separator thereby alleviating the possibility of line stoppage and reducing the fire hazard due to the presence of flammable liquids and vapors within the piping system b Outside installation Units installed outside of a building normally are provided to accommodate multiple fixtures and may be prefabricated or field fabricated type The advantages of this type of interceptor are a access is convenient for inspection and cleaning b cleaning is accomplished without interfering with normal operation of the facility and c servicing is confined to a single location 2 Sizing of Interceptors The size of interceptors depends upon the use and location When located inside of a building units used for intercepting solids and units used for intercepting volatile liquids shall be selected in accordance with manufacturer s recommendations For units located outside of a building see Civil Engineering Drainage Systems NAVFAC DM 5 03 Grease interceptors located i
18. by a small unit 1 2 gallon unit could meet the requirement but 2 units would be needed because a special faucet is required 1 kw 1 gallon unit is used Three units are required one for each lavatory and one for the slop sink Energy use calculations proceed as follows Present Circumstances Heating energy for lavatories E 8 3 x G x iron Tri1 where gal per year 3 x 25 x 250 8 3 x 3 25 x 250 x 140 120 0 70 E 16 674 107 Btu per year Heating energy for slop sink E 8 3 x 10 x 250 x 120 45 0 70 Ei 2 223 214 Btu per year Standby loss The loss from a 30 gallon oil heater set for 120 deg F in a 60 deg F average room cannot be determined from the literature It can be very roughly estimated at 1000 Btu per hour or 8 760 000 Btu per year 3 01 62 Line losses One hundred twenty feet of 1 2 inch water pipe are in the building and contain about 5 gallons Daily use is 85 gallons so it is assumed that line losses are again very small compared to total energy demand of the heater The total annual energy use for the existing water heater in this example is then heating energy plus standby loss 16 674 107 2 223 214 8 760 000 27 657 321 Btu per year The annual cost in this case would be 6 07 x 27 657 321 167 88 1 000 000 First Alternate Instantaneous Heaters It was shown that there is no heater available to provide a 60 deg F temperature rise at a flow rate of 5 gallo
19. deg C the cost to heat water with a WHHP at 0 08 per kWh would be 7 10 for one million Btu 293 kWh At a COP of 3 6 the cost would be 6 51 One million Btu 293 kwh represents an estimated one month s residential use at an average rate of 67 gallons 254 liters per day of hot water heated from 55 deg 13 deg to 115 deg F 46 deg Based on the cost of energy used above it is easy to see that if the outside ambient temperature is above 50 deg F 10 deg C for a significant number of hours during the time when hot water can be made and stored the WHHP may be an economical system to use It should be remembered that an outdoor air thermostat will not let the WHHP operate at ambient temperatures below 45 50 deg F 7 10 deg As a rule of thumb if the outdoor dry bulb ambient temperature for a given geographical location between the hours of 0800 to 2000 does not fall below 50 deg F 10 deg C for more than 350 hours per year the outdoor air source WHHP water heating system should be investigated During the 350 hours approximately one month the backup heater would be used to heat the hot water If during the remaining 4030 hours the WHHP could operate at an average COP of 3 3 the cost for one million Btu 293 kWh at 0 08 per kWh would be 7 10 The net saving for a year would be 39 16 when compared to gas heating at 0 80 per therm If the WHHP was installed for 650 00 on this project the payback would be 16
20. in and garbage refrigerators Steam cookers and steam jacketed kettles 3 01 7 3 Cold storage buildings are as follows Fat rendering processing salvage and receiving rooms b Receiving and issuing vestibules c Adjacent areas to meat coolers and milk butter and egg rooms 2 STORM DRAINAGE SYSTEM a General The storm drainage system consists of 1 the piping System used to convey rain water from roofs areaways and other areas exposed to the weather and 2 the sub soil drainage system The system Size shall be based on the rainfall intensities frequencies and duration indicated in Table 2 Downspouts Downspouts leaders may be exterior or interior Exterior downspouts usually are of sheet metal and require protection from damage when they are located in areas used for parking or truck loading Downspouts in such areas shall connect to steels or cast iron pipe 5 feet above the paving or loading platforms When exterior downspouts are to be connected to a storm sewer and are not in an area where damage is likely to occur they shall be connected above grade to an extension of the underground piping system Cs Sub Soil Drains A sub soil drainage system shall be provided to prevent water seepage through walls and floors located below grade Drains may be installed under floor or at outer perimeter of the building walls and shall be installed at an elevation so as to restrict the accumulation of sub
21. in the office building This installation will then provide a service water temperature range of 95 deg F tepid to 115 deg F non scalding With slop sink flow now reduced to 1 1 2 gallons per minute the proper size instant heater is 0 16 1 5 120 35 20 4 kw check maximum temperature at highest groundwater temperature one faucet case 20 4 0 16 1 5 55 T poy 140 deg F which is not too hot for janitorial use Select a 20 kW unit Heating energy for each lavatory 4 basins 8 3 x 12 1 2 x 250 95 115 45 2 1 638 158 0 95 4 basins 6 552 632 Btu per year Heating energy for slop sink 8 3 10 x 250 120 140 45 2 1 763 750 0 95 Total annual energy use for this alternative is 6 552 532 1 763 750 8 316 382 The annual cost in this case would be 14 60 x 8 316 382 121 42 1 000 000 3 01 65 Fourth Alternate Mini Tank with New Faucets and Flow Restrictors The incorporation of 1 2 gpm flow restrictors will permit setting the two lavatory tank thermostats to the desired service temperature and will eliminate the tampering valves Heating energy for each lavatory 2 basins E 8 3 x 25 x 250 95 45 2 730 263 Btu per year 0 295 2 lavatories 4 basins 5 460 526 Btu per year Heating energy for slop sink 1 638 158 from second alternate There is no benefit to installation of a flow restrictor unless it will reduce the size of the heater t
22. may be done by providing one heater to meet the demands of both pieces of equipment or specifying booster heaters as integral parts of the equipment 2 Semi Instantaneous The semi instantaneous type water heater has a high capacity heating coil and a small storage capacity It is suitable mostly for use where the hot water demands are characterized by a high sustained demand load with only small peaks on top of the sustained load The heating coil is sized to satisfy the high sustained demand load and the small peak demands are satisfied by the small amount of storage This type of water heater is not suitable for use in barracks quarters commercial type laundries and messing facilities These types of facilities because of their high peak demands of relatively short duration require a water heater with storage To determine the suitability and size of semi instantaneous water heater to be used for other than the above types of facilities an analysis in accordance with the following guidelines should be made a Guidelines for sizing The following information shall be used as a guide for sizing 1 Determine the estimated maximum hot water flow by the method described in the National Standard Plumbing Code 11 Determine the water heating capacity required in gallons per minute by multiplying the estimated maximum flow by the following factors hospitals 25 living quarters 33 subsistence buildings other than kitc
23. subsistence buildings bachelor officers quarters with mess and enlisted men s barracks with mess shall be provided with multiple water heaters and storage tanks Other facilities shall be provided with a single water heater and storage tank Multiple units however may be justified by circumstances such as 1 facility configuration 2 space limitations 3 limited access to tank room and 4 hot water requirements necessitating a unusually high capacity heating and storage unit When two units are provided each shall have a capacity equal to two thirds of the calculated load When more than two units are provided their combined capacity shall be equal to the calculated load 6 Relief Valves Automatic relief valves shall be provided for the protection of all water heating and storage equipment a Type A temperature relief valve and a pressure relief valve are provided for all equipment with a storage capacity in excess of 120 gallons 454 liters and an input rating in excess of 100 000 British thermal units per hour 35 000 watts A combination temperature pressure relief valve is provided for equipment with a storage capacity of 120 gallons 454 liters or less and a input rating of 100 000 or less British thermal 35 000 watts units per hour 3 01 22 b Capacity The pressure relief valve shall have a relieving capacity equal to or in excess of the input of the heater and it shall be set to relieve at or below the maxim
24. water pipes tanks and cooling tower will not prevent water from freezing these devices shall be insulated and possibly heat traced for protection against damage The proper thickness or conductivity factor for this insulation shall be determined by the design engineer e Design The insulation requirements and maximum heat loss rates stated in this section are minimum design requirements The designer is encouraged to upgrade the quality of insulation if he can show an improvement in the system performance or that the insulation is cost effective or both 3 01 26 Section 5 FUEL GAS SYSTEMS 1 DESIGN Design of systems for natural gas manufactured gas and liquified gases shall be in accordance with NFPA Standard No 54 National Fuel Gas Code and No 58 Storage and Handling of Liquified Petroleum Gases 2 SAFETY PRECAUTIONS Safety precautions for fuel gas systems are as follows a System Pressure Only low pressure gas approximately 5 inch 1 24 kPa water column shall be distributed within the building b Pressure Regulator Location In areas where outside temperatures remain above freezing the pressure regulators shall be installed within a ventilated enclosure adjacent to the building In areas where freezing temperatures are encountered location of regulators shall be in accordance with local policy Vent pipe from regulator shall terminate outside of building c Seismic Consideration In areas subject to eart
25. 0 deg F 7 10 deg C Below this temperature the backup heater must heat the water If outside air is the source of heat for the evaporator an analysis must be made of the number of hours the outside temperature is below 50 deg F 10 deg C the cost of electricity and the cost of the alternate energy to heat the water At some combination of these three factors the premium cost of the WHHP will rule out its use for domestic water heating because the payback will be too long Example 1 Assume that a WHHP has a COP of 2 2 when the evaporator air is at 50 deg F 10 deg C and 25 percent RH and that it generates 135 deg F 57 deg C hot water If electricity costs 0 08 per kWh 1 million Btu 293 kWh of heated water would cost Btu Electrical Cost x cost per kwh COP x 3 413 1 000 000 x 0 08 10 65 2 2 3 413 kWh cost per kwh COP 293 x 0 08 10 65 2 2 One million Btu 293 kwh of water heated by gas heater operating at 75 percent efficiency and using gas at 0 80 a therm 29 kWh would cost Btu Gas Cost cost per therm efficiency x 100 000 1 000 000 x 0 80 510 66 0 75 x 100 000 or kWh x 3 413 RV R cost therm efficiency x 100 000 293 x 3 413 x 0 80 10 66 0 75 100 000 301 33 If the ambient temperature were high enough to allow the WHHP to operate at a COP of 3 3 while heating water to 135 deg F 57
26. 05 55 3 5 101 200 0 6 0 04 85 5 4 201 400 0 5 0 03 125 7 9 401 up 0 4 0 025 210 13 0 Industrial 1 25 1 5 0 10 25 1 6 buildings 26 50 1 0 0 06 40 2 5 51 100 0 75 0 05 60 3 8 101 150 027 0 045 80 5 0 151 250 0 65 0 04 110 7 0 251 up 0 6 0 04 165 10 5 Quarters and 1 50 0 65 0 04 25 1 6 barracks 51 100 0 55 0 03 35 2 2 101 200 0 45 0 03 60 3 8 201 400 0 35 0 2 100 6 3 401 800 0 275 0 02 150 9 5 801 1200 0 25 0 015 225 14 5 1201 up 0 2 0 01 300 19 0 Schools 1 10 1 5 0 09 10 0 06 11 25 1 0 0 06 15 0 9 26 50 0 8 0 05 30 1 9 51 100 0 6 0 04 45 2 8 101 200 0 5 0 03 65 4 1 200 up 0 4 0 025 110 7 0 gt 3 Tank Capacity Tank capacity shall be based upon a withdrawal in gallons liters of 2 1 2 times the gallon per minute liter per second Capacity of the pump and a low water level of not less than 10 percent of total 3 01 12 tank capacity or 3 inches 76 mm above top of the tank outlet whichever is greater Table 4 indicates high water levels and withdrawals for efficient operation of tanks with bottom outlets and a 10 percent residual Using this table the tank capacity may be determined as per Example 1 Pressure ranges are given in pounds per square inch psi and kilopascals kPa 4
27. 1 Tank Pressure The minimum pressure maintained within the tank is at low water level and is equal to the pressure required to meet the fixture demands The high pressure at high water level depends on the operating pressure differential selected for the system A reasonable and most commonly selected pressure differential is 20 pounds per square inch 138 kPa 2 Pumps Pumps normally are provided in duplex Each pump is sized to meet the requirements of the facility Pump capacities in gallons per minute liters per second shall be in accordance with Table 3 Pump head shall be equal to the high pressure maintained within the hydro pneumatic tank 3 01 11 TABLE 3 Tank Fill Pumps SEENEN Min pump Location No of Gpm L s Capacity Fixtures per Fixture gpm L s lt Administration 1 25 1 23 0 08 25 1 6 building 26 50 0 9 0 06 35 2 2 51 100 0 7 0 045 50 3 2 101 150 0 65 0 04 75 4 7 151 250 0 55 0 03 100 6 3 251 500 0 45 0 03 140 7 8 501 750 0 35 0 02 230 15 0 751 1000 0 3 0 02 270 17 0 1000 up 0 275 0 02 310 20 0 Apartments 1 25 0 6 0 04 10 0 6 26 50 0 5 0 03 15 0 9 51 100 0 35 0 02 30 1 9 101 200 0 3 0 02 40 2 5 201 400 0 28 0 02 65 4 1 401 800 0 25 0 015 120 7 6 801 up 0 24 0 015 210 13 0 Hospitals 1 50 1 0 0 06 25 1 6 51 100 0 8 0
28. 20 60 1 660 000 Btu per year 0 75 Standby loss The heater is now in conditioned space 70 deg F 800 Btu per hour x 24 x 365 7 008 000 Btu per year Some analysts may choose to ignore this figure since the heat is not lost when the water heater is in conditioned space slop sink closet However the tank to air heat transfer does generate an operating cost which must be accounted for in the life cycle cost analysis Total annual energy use 8 300 00 1 660 000 7 008 000 16 968 000 Btu per year 367 x 16 968 000 62 27 per year 1 000 000 3 01 68 Second Alternative Instant Heater Recheck basin heater size for 65 deg F and 55 deg F R 0 16 1 2 95 55 3 2 kW 3 2 0 16 1 2 65 105 A 3 kw 110 V unit may now be used Heating energy for each lavatory 4 basins 8 3 x 12 1 2 x 250 95 105 60 x 4 4 368 421 Btu per year 2 0 95 Heating energy for slop sink 8 3 x 10 x 250 120 130 60 1 419 737 Btu per 2 0 95 NOTE If used as booster for 95 deg F water 546 052 Btu Total annual energy use 4 368 421 1 419 737 5 788 158 Btu per year 14 56 x 5 788 158 84 28 per year 1 000 000 Third Alternative One Gallon Tank Heater Heating energy for lavatories E 8 3 x 2 25 x 250 x 95 60 3 822 368 Btu per year 0 95 Heating energy for slop sink 8 3 x 10 x 250 x 120 60 1 310 526 Btu per year 0 95 Standby losses from example 2
29. 6 years which may not be attractive When compared to direct resistance heating of water costing 23 43 per month at 0 08 per kwh the savings per year would be 195 96 for a payback of 4 2 years which is very attractive and is based upon present value of money discounted 10 percent The conclusion to be drawn is that the designer must analyze the cost of electricity and other fuels the geographical weather conditions per data in NAVFAC P 89 Engineering Weather Data and the premium cost of the WHHP system to determine the most economical way to heat water The cost of electricity is the amount the utility charges the Government for power not the amount the Government charges its users The analysis of the economies of using a WHHP must include a determination of the system s impact on the electric demand Time of use rate schedules for electricity such as on peak mid peak off peak winter summer etc may have an important bearing on the type of water heating system to be used 3 01 34 Equipment Location An air source WHHP will be more efficient if it is located in an area where there is a good source of waste heat such as near a boiler furnace clothes dryer etc or near the ceiling where the warmest air collects The air source heat pump evaporator requires a air flow rate of approximately 450 cfm 0 21 mb34 sec for approximately 15 000 Btu h 4 4 kWh heat rejection Normally outside air is the source of evaporator
30. ATER SOURCE HEAT PUMPS Condenser Water Source Exhaust Air to Water Process Fluid Groundwater Buried Pipe 222 22 Storage Tanks and Standpipes Solar Thermal Storage HEAT RECOVERY AIR CONDITIONING SYSTEMS a Auxiliary Condensers b Desuperheater HEAT RECOVERY FROM REFRIGERATION a Auxiliary Heat Exchanger b Water Loop SOLAR DOMESTIC HOT WATER a System Types b Applications c Performance d Economics e Design Criteria WATER TO WATER RECOVERY POINT OF USE HEATERS a Booster Heaters b Line Heaters c Modular Boilers WWWW WW WwW GA C C GA GA CO WWW GA Page 01 29 01 29 01 29 01 29 01 32 01 33 01 35 01 35 01 35 01 35 01 36 01 36 01 39 01 39 01 39 01 39 01 40 01 40 01 42 01 43 01 43 01 01 43 01 43 01 48 01 47 01 48 01 49 01 51 01 51 01 51 01 52 01 52 Page 8 TOTAL ENERGY RECOVERY s 3 01 53 Cogeneration Be ok a 0e a 3 01 53 b Stand Alone System 3 01 53 POWER BURNERS g lt x lt amp 3 01 55 a Water Heaters 3 01 55 b Tankless Heaters 3 01 55 10 CONTFROLe zuo 54 ko c9 w 79 3 01 56 a In Line Flow Regulators
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32. Pressure Excessive water pressures will result in a excessive flows at fixtures with a resultant waste of water b high velocities with a resultant noisy piping system and c water hammer with a resultant noise and destructive effect on the piping and fixtures The installation of pressure regulating valves shall be considered when the residual pressure at fixtures exceeds 50 pounds per square inch 345 kPa The pressure reducing station shall consist of a pressure regulator strainer isolating valves pressure gauges and a reduced size bypass with a manually operated flow control valve 2 Inadequate Pressure When water pressure is inadequate means for increasing the pressure shall be provided For pressure booster systems see Part 2 of this section 3 Velocities Normally water velocities shall not exceed 10 feet per second 3 28 m s In hospitals and similar facilities where a quiet system is desired velocities shall not exceed 7 feet per second 2 13 m s Bz Water Hammer Arrestors Water hammer arrestors shall be provided only in conjunction with automatically operated quick closing valves Arrestors shall be the mechanical type and shall be sized and located in accordance with Water Hammer Arrestors PDI WH201 2 BOOSTER SYSTEMS AND PUMPS a Hydro Pneumatic System Water pressure may be increased by using a hydro pneumatic system consisting of a tank pumps compressed air system and associated control devices
33. R STORAGE HEATER NOTES OUGRAMS ILLUSTRATE THE LOCATION RELIEF VALVES WHEN SEPARATE TEMPERATURE AND PRESSURE RELIEF VALVES ARE REQUIRED THE LOCATION OF THE TEMPERATURE RELIEF VALVE INDICATES ALSO THE LOCATION OF THE COMBINATION TEMP PRESSURE RELIEF VALVE WHEN THE COMBINATION VALVE 15 REQUIRED PAR 35 6 b 2 WHEN ADEQUATE CIRCULATION BETWEEN STORAGE TANK AND HEATER CANNOT BE ACHIEVED BY GRAVITY CIRCULATING PUMP SHALL BE PROVIDED FIGURE 1 Typical Connections to Water Heaters and Hot Water Storage Tanks 3 01 24 Section 4 INSULATION OF PLUMBING SYSTEMS 1 HOT WATER SYSTEMS Insulate service hot water piping and storage to meet the following minimum requirements a Unfired Water Storage The heat loss from unfired storage tanks shall not exceed 13 Btu per hour per square foot 41 watts per square meter of external tank surface area at a design ambient of 65 deg F 18 deg C and shall not exceed the temperature of the stored water b Electric Water Heaters Insulate all electric water heaters and backup heaters with a storage capacity of 80 gallons 303 liters or less and an input rating of 12 kW or less to limit the heat loss to less than 13 Btu per hour and per square foot 41 watts per square meter of the external tank area Also insulate heaters based on a temperature difference of 80 deg F 44 deg C Insulate electric storage heaters with storage capacity greater than 80 gallons 303 liters or
34. air but if building air is used it must be able to pick up heat within the building without causing drafts or uncomfortable conditions in the occupied spaces The air discharged from the evaporator is cooled and dehumidified It may be used to supplement existing space cooling in warm weather or to help control humidity in moist areas or it may be exhausted to the outside The outside air intake and exhaust outlet must be adequately sized and located so the two air streams do not mix The designer must follow the manufacturer s limits for maximum static pressure when the supply and exhaust air are ducted All supply and exhaust openings in the buildings must be provided with protection against the entry of precipitation animals birds etc In colder climates dampers are required In geographic areas where freezing temperatures are common the location and installation of the WHHP must provide freeze protection for the water piping When a WHHP is installed outside or in a space where freezing temperatures occur the designer must specify that the WHHP have a built in thermostat to turn on the circulating pump when the outside air temperature is below 42 deg F 6 deg C The pump will circulate warm tank water through the unit and prevent freezing of the pipes In colder climates basements and some crawl spaces tend to be maintained at 50 deg F 10 deg C by heat gain from the earth making these areas acceptable locations for the installation
35. and Domestic Hot Water Systems 1 Water Treatment Means should be provided for occasional or continuous treatment and monitoring of all heat transfer fluids 3 Expansion Tanks An expansion tank should be provided for any closed circulation system k Piping The type of piping selected should be compatible with the fluids employed Pipe insulation should be in accordance with Section 4 of this manual The designer must perform an energy and economic evaluation to determine if additional insulation is warranted The designer should provide dielectric or nonmetallic couplings when joining dissimilar materials provide for pipe expansion over the range of temperatures to be encountered slope all piping requiring drainage at least 1 4 inch per foot and provide automatic air vents at all high points in the piping Whena multiple collector system is used reverse return piping with balancing valves and flow indicators should be used 3 Other Considerations There are several other considerations when designing solar systems a Freeze Protection Where the possibility of freezing exists provision should be made to preclude damage to the solar system b Stagnation The designer should make adequate provision to accommodate the temperatures encountered during times when there is no flow through the solar collectors 3 01 50 c Corrosion Where the possibility of corrosion exists provisions should be made to test and add inhi
36. any energy conservation system s cost reduction must be based on the cost of energy to the Government See 10 CFR 436 14 c Methodological Assumptions With the continued increase in the costs of all forms of energy conservation becomes more attractive The many formulas for computing the cost of electric energy cannot be explained in this manual and a quick guide to comparing the costs of fuels is offered instead The quick guide to the costs of hot water and energy is given in Figure 13 Hot Water Energy Costs which converts the unit cost of fuel dollars per 1 000 000 Btu 293 kWh for various systems and fuels b Example Determine the costs per 1 000 000 Btu 293 kWh to heat water with a WHHP using electricity at 0 09 per kWh and operating at a COP of 3 2 Determine the costs per 1 000 000 Btu 293 kWh for a gas water heater using gas at 0 75 per therm 29 kWh and having an atmospheric burner of 75 percent efficiency For the WHHP enter the graph at 0 09 per kWh project up to the 3 2 COP line then left to read 8 24 per 1 000 000 Btu 293 kWh 3 01 56 Las NX WR D NITE x TL RA H a FECEPRLGCCEEELESNN Cs a For gas enter at 0 75 per therm 293 kWh project up to the G curve t
37. are added to their equipment without their prior approval In such a case if a modification is made and something happens to a system component the contractor and the Government will have to pay for any repairs required The designer s solution to this problem is not to accept or use such manufacturers equipment or not to attempt field modifications of their equipment 1 Existing Equipment If the designer determines that existing equipment still under warranty will be modified with the addition of a desuperheater or auxiliary condenser the manufacturer should be consulted The manufacturer will be able to provide such information as the maximum size desuperheater permitted the maximum pressure drop allowed the minimum head pressure required for proper operation and other factors that will guide the designer or that may change the warranty 2 Assurance The specifications for a WHHP must call for the equipment to be Underwriters Laboratories Inc UL listed and must indicate the pressure class of the water side of the equipment This will ensure that the equipment meets the pressure class and electrical requirements of UL and the Navy 3 01559 PAGE 60 INTENTIONALLY BLANK APPENDIX A ENERGY ANALYSIS EXAMPLE a Selection of point of use water heaters will be dependent on energy Savings and cost effectiveness based on life cycle cost analysis Each retrofit and new construction opportunity must be analyzed to determine
38. be tolerated or where failure of a system would drastically reduce the efficiency of a facility components of the system which are subject to failure shall be provided in duplicate Material and Construction 1 Aesthetics Ornate decoration is not required Simple clean and functional design shall be stressed 2 Materials Use noncombustible materials for plumbing systems 3 Health and Sanitation In material selection consider health and sanitation for personnel served by the systems and for operating and maintenance personnel d Protection of Computers and Other Equipment from Water Damage 1 Computer areas within buildings should be located to minimize exposure to water and other listed hazards from adjoining areas and activities see NFPA 75 81 Protection of Electronic Computer Data Processing Equipment 2 The floor above computer room should be waterproofed to prevent passage of accidental spillage 3 Chilled water piping domestic water supplies sanitary drains roof drains gas lines fuel oil lines steam lines water mains and other utility lines not serving the electronic equipment area shall be prohibited from the electronic equipment and record storage areas 3 01 2 4 Utilities containing water or other fluids which serve the electronic equipment and record storage areas shall be routed not to pass directly over electronic equipment or stored records whether installed over or below the finishe
39. below grade shall be protected against backflow e Food Waste Grinders Food waste grinders shall be installed only with the approval of local authorities Unit shall be equipped with a P trap on its outlet and shall discharge directly into the sanitary sewer and never through a grease interceptor f Floor Drains Floor drains with suitable drain traps shall be provided for certain equipment and areas A single floor drain may serve more than one area When it is anticipated that a floor drain trap may lose its water seal because of infrequent use means for automatically maintaining the seal shall be provided Automatic priming of traps may be by a drain from a fixture within the area or by a connection to the water system When automatic priming is through a device connected to the water system that device shall be equipped with a vacuum breaker Floor drains are not required in service sink rooms and transformer rooms Floor drains serve but shall not be limited to the following areas and equipment 1 Gang toilets shall be interpreted as those having three more water closets and gang shower drying rooms as those serving two or more showers 2 Subsistence buildings are as follows a Dishwashing scullery or pot washing and food cart washing areas Vegetable peelers and vegetable preparation areas Steam table and coffee urn areas Soda fountain area Adjacent areas to ice chests ice making machines and walk in reach
40. bitors d Maintainability The designer should require the preparation of detailed operating and maintenance instructions e Equipment Location All components of the solar system other than piping ductwork and wiring should be readily accessible Where collectors and other equipment are located on the roof means should be provided for routine inspection and maintenance Acceptance Testing The designer should require that each solar system be formally tested to demonstrate its performance prior to acceptance 6 WATER TO WATER RECOVERY Some buildings have equipment or processes that use high temperature fluids or have large steam condensate discharges that can heat hot water By circulating hot fluid at 110 deg F 43 deg C or higher through one side of a plate heat exchanger and potable water through the other side potable water can be directly heated and stored for use in a building A plate heat exchanger or a double wall heat exchanger must be used to prevent contamination of the potable water A plate heat exchanger eliminates possible contamination because a leak in either water circuit will be to the atmosphere 7 POINT OF USE HEATERS a Booster Heaters The most energy efficient hot water heating system is one that heats water to the lowest possible temperature has no heat loss heats only as needed and has no storage capacity A heater that comes closest to fitting this description is a booster or an instantane
41. ble acceptable water temperature Time clocks can be used to shut off the water heater supply system and the circulating pump when the building is unoccupied however the designer must check to see if the heat loss from the water heater system during the unoccupied time is greater than the energy used to bring the system water temperature up to the thermostat setting each morning when the building is occupied The system with the lower operating cost should be the basis of design 3 01 58 12 RATINGS AND WARRANTIES a Capacity All water heaters should have heating and recovery ratings certified by the appropriate national society or association for gas oil or electric water heaters At this time there is no rating group for the WHHP or for desuperheaters The WHHP manufacturers are presently using the Gas Appliance Manufacturers Association GAMA method to determine the heating and recovery rate of a WHHP This may be a good way to rate the equipment However the designer is cautioned that the GAMA method of determining recovery rate account for WHHP capacity changes as the ambient air temperature changes and that there is no rating group that has enforcement powers It is therefore a good idea to write both an equipment and a performance specification for WHHP equipment b Special Problem Some manufacturers of refrigeration and air conditioning equipment void their warranties or guarantees if desuperheaters or auxiliary condensers
42. ceptable criteria the water temperatures shown in Section 3 of this manual shall be used 3 Backup System The backup system for the solar hot water system should be sized by assuming the solar system does not operate and should be in accordance with Section 3 of this manual Before using the backup system use two tanks in the system design to make maximum use of solar heated hot water 4 Operating Energy Energy used for pumps and fans and heat losses in the solar system should be minimized by the designer and included in the performance evaluation 5 Conventional Systems The performance evaluation of solar hot water systems should include any impact on the performance of backup systems such as reduced efficiency or increased losses when making comparisons with conventional hot water systems d Economics Economic evaluations of solar hot water systems should be made and compared with conventional hot water heating systems 1 First Cost The installed cost for the solar system should be determined including all other modifications to the hot water system and to the building that are necessary for proper operation and maintenance a Solar Equipment Include all costs for collectors piping insulation pump and fans and controls b Backup Equipment Include all costs for backup water heating system 2 Operating Cost All costs associated with operation and maintenance of the solar system should be included in the
43. d ceiling 3 01 3 PAGE 4 INTENTIONALLY BLANK Section 2 DRAINAGE SYSTEMS qi SANITARY SYSTEMS a Sumps and Sump Pumps Drains which cannot discharge into the building sewer by gravity shall discharge into a tightly covered and vented sump from which the effluent will be pumped 1 Sumps Sumps shall be sized so that their contents in gallons liters between high and low water level will be approximately twice the capacity of the sump pump in gallons per minute liters per second In Sizing the sump it must be remembered that the high water level must be somewhat lower than the inlet to the sump and the low water level will be approximately 1 foot above the bottom of the sump 2 Sump Pumps Sump pumps are classified and arranged as follows a Classification Sump pumps are intended for use where drainage is free of solids Sewage ejectors are intended for use where drainage contains solids b Number required Provide a single unit where the function of the equipment is not critical and provide duplex units where the function of the equipment is critical and where six or more water closets are being served When duplex units are provided the capacity of each unit shall be sufficient to meet the requirements of the facility c Controls Automatic controls shall be provided for each pump Duplex units shall be equipped with controls to alternate the operation of the pumps under normal conditions and to operate pumps sim
44. data available and contact the manufacturer for advice 4 HEAT RECOVERY FROM REFRIGERATION a Auxiliary Heat Exchanger Low temperature refrigeration systems such as beverage coolers cold boxes freezers etc in galleys clubs commissaries and buildings with subsistence facilities are other sources of heat for hot water The installation of an auxiliary double wall vented heat exchanger or desuperheater hot gas line can generate up to 135 deg F 57 deg C water depending on entering water temperature and flow rate Low temperature refrigeration equipment usually has a long on cycle and is therefore a fairly reliable source of heat when combined with a properly sized storage system or when used as a preheater for the water heating system A refrigeration system often has a low cooling capacity and therefore requires a large hot water storage capacity Several refrigeration systems can be fitted with desuperheaters to provide enough hot water to satisfy usage or to serve as preheaters b Water Loop Refrigeration equipment with water cooled condensers is sometimes used in commissaries for freezer and display boxes The condenser water loop is another source of heat for the water to water heat pump previously discussed 53 SOLAR DOMESTIC HOT WATER a System Types Several types of systems are used 1 Thermosiphon Systems As shown in Figure 10 Typical Solar Systems thermosiphon systems heat potable water directly and
45. drain completely 5 Indirect Water Heating Systems An indirect water heating system Figure 10 circulates a freeze protected heat transfer fluid through the closed collector loop to a heat exchanger where its heat is transferred to the potable water The most commonly used heat transfer fluids are water ethylene glycol and water propylene glycol solutions although other heat transfer fluids such as silicone oils hydrocarbons and refrigerants can also be used These fluids are nonpotable are sometimes toxic and require double wall heat exchangers The double wall heat exchanger can be located inside the storage tank or an external heat exchanger can be used The collector loop is closed and therefore requires an expansion tank and a pressure relief valve One or two tank storage systems can be used Additional over temperature protection may also be needed to protect the collector fluid from decomposing or becoming corrosive Designers should avoid automatic water makeup in systems using water antifreeze solutions because a significant leak may induce enough water into the system to raise the freezing temperature of the solution above the ambient temperature causing the collector array and exterior piping to freeze Also an antifreeze system with a large collector array and long pipe run may need a time delayed bypass loop around the heat exchanger to avoid freezing the heat exchanger on startup 3 01 46 6 Air Systems An air sy
46. e Wall Heat Exchange Water Heater To Floor Drain Compressore Service Valve FIGURE 4 Exhaust Air Heat Pump b Exhaust Air to Water Where an exhaust system is on during occupancy exhaust air can be the heat source for a closed loop water source heat pump Installing a cooling coil in the exhaust duct allows the heat pump to be installed in an equipment room near the storage tank some distance away See Figure 6 Exhaust Air Heat Source If a heat recovery coil is installed in a new or existing exhaust duct system the designer must evaluate the impact of the added coil pressure drop on the operation of the exhaust fan the cost of duct transitions and the cost of the coil piping and the pump These added costs must be charged to the water heating system The addition of a cooling coil to an existing exhaust system in some cases may require a larger exhaust fan motor c Process Fluid Some buildings require cooling water for such things as computers condensate coolers process cooling etc This cooling water is a good source of waste heat that can be used by a water to water heat pump Generally the fluid temperature should be no lower than 50 deg F 10 deg C for an efficient system A heat exchanger should be used between process water and the heat pump where the fluid and the materials of the heat pump evaporator are not compatible or where the temperature of the process fluid is high and requires r
47. economic analysis Energy Include all costs of energy to operate the solar system and backup water heating system as determined in the performance evaluation in paragraph 5c b Operation Include all costs for people equipment and supplies necessary for day to day operation and inspection of the solar system c Maintenance Include all costs for regular maintenance of the system and for reasonable unexpected maintenance and repair 3 Life Cycle Cost A complete life cycle cost analysis should be performed using NAVFAC P 442 Economic Analysis Handbook procedures 3 01 48 e Design Criteria 1 Sizing The sizing of major solar system components should be determined to minimize life cycle cost and provide flexibility to operate under a variety of conditions normally encountered Collectors Solar collectors should be sized by one of the methods in Chapter 57 of the ASHRAE Handbook 1984 Systems the ASHRAE Solar Heating of Domestic and Service Hot Water Manual or MIL HDBK 1003 13 Solar Heating of Buildings and Domestic Hot Water b Storage Sizing of hot water storage should be in accordance with Section 3 of this manual and may be increased when necessary to allow greater utilization of solar energy economically c Backup System Sizing of the backup hot water heating system should be in accordance with Section 3 of this manual assuming no contribution from solar Where the energy used in the backup sys
48. ed only where the hot water demand is relatively constant or where there are no periods of peak demand which would necessitate the selection of a unit that except for relatively short periods of the day would be grossly oversized Fluctuating water temperature is a characteristic of an instantaneous heater To guard against scalding and to ensure a constant predetermined water temperature at the fixtures a water mixing valve shall be provided as an auxiliary to the unit The instantaneous water heater must be capable of heating the water as it is being used The capacity of the unit expressed in gallons per minute is calculated by the fixture unit method For heater capacities for one and two family living units see Table 8 30 1 20 4 Water Heaters for Laundries Water heaters are provided for laundries according to hot water requirements based on the capacity of washers in pounds kilograms of dry clothes or the number of persons to be served by the plant Storage capacity in gallons liters shall be equal to 80 percent of the hourly heating capacity Total heating capacity Hmm and peak demand Dn of hot water based on capacity of washers in pounds kilograms of dry clothes will be computed as in Equations 1 and 2 EQUATION Rx 5 x 0 60 gph 1a or Hpw R x 41 6 0 60 Lob 1b EQUATION Dw R x 5 x 0 60 gpm 2a 3 x F x C or Drwq R x 41 6 x 0 60 Lpm 2b Sox Ix where R total rated capacity of was
49. egulation to protect the heat pump 3 01 36 Hot Water To Building Relief Valve Head Pressure Regulator ne Tube 1111 Water Heater Double Wall Heat Exchanger Cold Water Water to Water Heat Pump Condensing Unit Comfort A C Unit FIGURE 5 Water to Water Heat Pump 3 01 37 Exhaust Fan Heat Recovery Coil Exhaust Air Hot Water To Building T P Relief Valve Evaporator Tube Water Heater Double Wall Heat Exchanger Drain Water to Water Heat Pump Cold Water Circulating Pump FIGURE 6 Exhaust Air Heat Source 3 01 38 d Groundwater The natural groundwater temperature in many geographic areas is 50 deg F 10 deg C or above which is ideal for a water to water heat pump The designer must determine if there is an adequate water flow rate from the well to satisfy his project and must also determine if there are any code or EPA requirements concerning surface discharge of the pumped water or if the water must be returned to an aquifer e Buried Pipe The soil temperature at some depth below the freeze line is in some locations 55 deg F 13 deg C or above allowing the earth to be used as a heat source It transfers heat to water circulated in a closed loop in buried pipes Such a system includes a field of pipes buried in horizontal trenches or in vertical wells or holes and back
50. emand of the building Figure 8 Heat Recovery A C System with Auxiliary Condenser is a simplified diagram of this system Additional valves and controls are needed to make this completely automatic system All the energy required for heating water is free with this system 1 The addition of a water cooled condenser to an air conditioning system for the purpose of heating potable water can create both high and low head pressure problems if the system is not properly controlled Therefore the flow of refrigerant to the heat recovery water cooled condenser is regulated by controlling the refrigerant pressure in the air or water cooled condenser Referring to Figure 8 Heat Recovery A C system with Auxiliary the solenoid energized liquid line regulator 1 when not activated acts as a pressure regulator opening farther as the pressure increases This occurs during the heat recovery mode During the cooling only mode the Solenoid is energized and the regulator opens to pass the full flow of refrigerant The pressure setting of this device determines the temperature of the hot water 3 01 40 Circulating Pump Air Cooled Double Wall Condenser Hot Water Auxiliary To Building Condenser Service us T P D etter Service Valve Water Heater and Storage TET Hot Gas Service EES Drain Cold Water Expansion Valve Crm Compressor Liquid Line Air Conditi
51. eous unit may be used This unit may be used provided that the additional instantaneous steam demand of the unit as compared to a storage type unit which can be assumed to be semi proportional to the difference in coil size can be tolerated The semi instantaneous unit can also be used provided that use of the unit can be justified by an economic analysis Such an analysis would take into account any differences in the capital cost of boiler plant and steam service line the installed cost of the water heaters and the cost of mechanical room space if affected iv If the coil capacity thus determined is less than two thirds of the capacity which would be required for a semi instantaneous unit sized in accordance with paragraph a above it can be assumed that the demand for hot water in the facility is not of the sustained type and that use of the reduction factors in paragraph a ii are not justified Instead resize the unit assuming that the water heating capacity required is equal to the maximum hot water flow determined in paragraph a above A semi instantaneous heater sized on this basis may be used provided that the additional instantaneous steam demand of this unit as compared to a storage type unit can be tolerated and that use of the unit can be justified by an economic analysis see paragraph b iii 3 Instantaneous Type The instantaneous water heater has little or no storage capacity This type of unit shall be provid
52. erature boiler only when there is a demand for higher temperature water 1 If there is wide variation in the amount of hot water used at one temperature as in barracks a modular boiler system can be designed to automatically stage as many boilers on and off the line as are required as the usage increases and decreases This matches the modular boiler system s Capacity to the usage keeps each burner efficiency high and minimizes or eliminates storage capacity 2 When fossil fuel burning water heaters are used the designer must look at state of the art energy saving equipment such as condensing boilers pulse burners and stack combustion air heaters 3 01 52 8 TOTAL ENERGY RECOVERY a Cogeneration Whenever a facility has a large repetitive daily demand for hot water and at the same time requires electricity a cogeneration unit with heat recovery should be analyzed One facility that can use this equipment is a laundry With a heat recovery cogeneration system heat from the engine radiator crankcase oil and exhaust gases is recovered and used to heat or preheat the domestic hot water through a water to water heat exchanger The heated water is then stored to satisfy the hot water demand variations The electrical output of the generator with parallel feed is used to supplement the existing electrical service not replace it There are manufacturers claiming that the packaged cogenerator and heat recovery unit can u
53. eries Fire Protection for Facilities MIL HDBK 1008 Engineering Design and Construction 4 POLICY Plumbing systems design shall provide economy and reliability and shall conform with the following codes standards or specifications Subject Applicable Code Specification or Standard Design Criteria fixture allowances DOD 4270 1 M Construction Criteria Manual Fuel gas system National Fire protection Association NFPA Standards No 54 and No 58 Grease interceptor Plumbing and Drainage Institute PDI Standard PDI G101 Piping material valves etc NAVFAC Specification NFGS 15400 Plumbing fixtures etc NAVFAC Specification NFGS 15400 3 01 1 Subject Applicable Code Specification or Standard Water drainage and venting National Standard Plumbing Code systems Uniform Plumbing Code Basic Plumbing Code Water hammer arrestors Plumbing and Drainage Imstitute Standard PDI WH201 a Economy Systems shall be designed to effect the greatest possible economy 1 Fixtures equipment and piping Fixtures equipment and piping material shall be compatible with the life of the structure 2 Piping arrangement In permanent type structures piping shall be concealed In limited life structures piping shall be installed exposed except when specific project criteria justify concealment or where concealment will not increase the cost of the project b Reliability Where interruption of a service cannot
54. evaporator This system can be applied in areas where long periods of cloudy weather are normal See Figure 7 Solar Water Source Heat Pump for system details The size of the domestic hot water storage tank is based on the facility s hot water use and demand as determined in previous sections of this Design Manual The sizing of the solar collector and storage tank is determined by hot water usage and solar data as presented in MIL HDBK 1003 13 Solar Heating of Buildings and Domestic Hot Water ASHRAE s Solar Heating of Domestic and Service Hot Water Manual and paragraph 5 Section 6 of this manual 3 01 39 Solar Collector Hot Water to N Building Solar Circulating Pump T P Relief Solar Water Heat Sink Tank Temperature Control Valve Heat Source Circulator Double Wall Condenser Heat Exchanger Insulated Hot Water Heater MA Cold Water FIGURE 7 Solar Water Source Heat Pump 3 HEAT RECOVERY AIR CONDITIONING SYSTEMS a Auxiliary Condensers Any building requiring comfort air conditioning A C whenever the building is occupied has a good source of free heat for heating water The A C system requires the installation of an auxiliary double wall vented condenser in parallel with either the standard water cooler or air cooled condenser This system can provide as much heat for heating water as would normally be rejected to the atmosphere through the standard condenser or be sized to meet only the hot water d
55. filled This is a renewable source of heat Provide cathodic protection for buried pipe and dielectric couplings for iron to copper connections The designer must be specific about the type of backfill used around the pipe This is necessary to ensure good thermal conductivity between the ground and pipe plastic iron copper and eliminate air gaps Backfilling with lumpy soil especially clay construction rubble cinders etc causes poor thermal conductivity due to air gaps and possibly corrosive attack of the pipes f Storage Tanks Standpines Large storage vessels used to store potable water and pressurize water sprinkler systems particularly in warm geographic areas are huge thermal storage vessels Water can be pumped from a tank through the evaporator of a water to water heat pump and back to the tank to recover heat This system is limited to those buildings having such storage tanks which represent an inexpensive source of heat for a heat pump 92 Solar Thermal Storage thermal storage tank heated by a solar collector is a good source of heat for a water to water heat pump Ina solar heat pump system the solar water heat sink tank can be drawn down from 135 deg F 57 deg C to 50 deg F 10 deg C The conventional system draws the tank down to about 105 deg F 41 deg C The heat pump system must have a temperature control valve in the evaporator pumped circuit to limit the maximum temperature of water fed to the
56. g periods of time the system efficiency of an atmospheric burner heater is even worse than the 5 percent difference already noted The additional convective losses can reduce the system efficiency by an additional 3 to 10 percent See Figure 12 Power and Atmospheric Burners b Tankless Heaters When the demand for hot water is of short duration an instantaneous tankless water heater should be considered A tankless heater has very little storage capacity and heats only when there is a demand for hot water therefore there is little tank heat loss and the system efficiency is improved The analysis of a tankless heater fora project must include its impact on fuel cost fossil fuel or electric Some electric utility rate schedules impose an extra charge for high surge loads at certain times of the day Hot Water to Building Hot Water to Building Sa Fire Tubes with Few Baffles Atmospheric Burner Power Burnar FIGURE 12 Power and Atmospheric Burners 10 FLOW CONTROL a In Line Flow Regulators Flow regulators must be installed in hot water pipes to all fixtures other than washing machines and dishwashers to limit the maximum flow regardless of pressure variations and to conserve water heater energy Most devices are tamperproof when installed in hot water pipes The control mechanism of one device consists of a cup with holes in its side The cup is spring loaded so that it moves in response to changes in the pressure dro
57. gu Z 91 9 1 Z Sutseg 28728 ing 3008 321440 peste U93u2315 _ _ M se 9 09 2 071 39 9Jn3XIJ Jo jo SsedAI 194 puemaq 9 91454 TABLE 7 Estimated Hot Water Demand Characteristics for Various Types of Buildings Type of Daily demand Max hourly Duration Storage Heating of gal liters demand 1 lof Sus 1 Capacity Building per person gal liters tained gal gal 1 hrs liters liters er hr tt Adminis 3 11 20 76 2 20 76 16 61 tration Bachelor officers apartment 40 2 151 2 15 57 4 18 68 14 53 quaters 135121 132 2 25 95 2 20 76 15 57 Barracks with subsistence 40 151 12 45 2 5 10 38 8 30 Barracks without subsistence 30 2 114 14 53 12 45 8 30 Hospital 3 Industrial 19 30 114 1 20 76 20 76
58. he extra piping The designer must contact the compressor manufacturer to determine its special requirements for refrigerant controls piping and temperature limits for this system 2 Refrigerant Piping When an auxiliary condenser is added to a system the designer must design the refrigerant piping and physically locate the components of the system to prevent liquid slugging of the compressor and the production of flash gas ahead of the expansion valve The designer must size and pitch the gas lines to promote the return of oil to the compressor The auxiliary condenser should be near and at the same level as the standard condenser and drain the condensed refrigerant to a common receiver An oversized receiver is required for this system When this system is located in colder geographic areas head pressure control through the use of cycling fans damper modulation or a combination of both must be incorporated into the design to provide adequate head pressure regulation for the expansion valve and to ensure that heat recovery works properly If freezing temperatures are possible the water lines outside the building must be protected from freezing by heat tracing The hot water pipe and refrigerant lines must be insulated to reduce heat loss b Desuperheater When the hot water requirements in a building do not require a major portion of the heat available from condensing refrigerant a double wall vented desuperheater can be installed for heat
59. heat the incoming water to 140 deg F 60 deg C rather than through 100 deg F 37 8 deg C rise which is commonly assumed b Water Heaters Single or multiple water heaters with applicable protective devices shall be provided to meet various storage requirements and hot water demands 3 01 14 1 Storage Type The storage type heater is normally provided where hot water demands are not constant and where it is economically advisable to provide water storage to satisfy periods of peak flow The storage capacity of the unit serves to supplement the heating capacity and to permit the use of a unit with a relatively reduced recovery rate a Limitations on use of electric resistance domestic water heating The use of electrical resistance heating for domestic hot water is prohibited on storage tanks over 80 gallons 303 liters unless the following requirements can be met 15 An engineering analysis indicates electric heating to be the most economical method on a life cycle basis and 2 Provision is made to generate the hot water off peak by providing larger storage tanks or by storing it at a higher temperature of 160 deg F to 180 deg F 71 1 deg C to 82 2 deg C and distributing it through a blending valve at the desired temperature of 100 deg F to 110 deg F 37 8 deg C to 43 3 deg C and 3 The facility has a maximum total energy consumption of less than 60 000 Btu s per square foot per year 681 4 MJ mlLl24 a at a
60. hen and dishwashing equipment 33 for kitchen and dishwashing equipment see paragraph iii below and office buildings 25 For other types of buildings use the factor above for the buildings having a demand rate which most nearly approaches the demand rate of the building in question iii addition to the estimated maximum flow as determined above hot water to satisfy the simultaneous and continuous demand of special group fixtures commercial type laundry machines and kitchen and dishwashing equipment in subsistence buildings shall be provided when applicable 3 01 19 b Guidelines for determining suitability The following information should be used to determine suitability of use 1 Determine the coil capacity in gallons per hour liters per hour of hot water which would be required with a storage type heater sized in accordance with Table 6 11 the coil capacity thus determined is equal to or greater than the coil capacity which would be required for a semi instantaneous unit determined in accordance with paragraph a above it can be assumed that maximum instantaneous steam demand of the semi instantaneous unit will not be significantly greater than that of a storage type unit In this case the semi instantaneous unit should be used 111 the coil capacity thus determined is less than but at least two thirds of the size which would be required for a semi instantaneous unit the semi instantan
61. hen left to 10 00 per 1 000 000 Btu 293 kwh For a gas water heater to be comparable to a WHHP operating at 3 2 COP gas would have to cost 0 61 per therm 293 kWh This is determined by entering the graph on the left at 8 24 per 1 000 000 Btu 293 kWh the cost for the WHMP projecting right to the G curve and reading down to the price of gas of 0 61 per therm 293 kWh To compute electric costs per 1 000 000 Btu 293 kWh use Equation 8 EQUATION 293 C req 8 COP where Cre4 cost of electricity per kilowatt hour dollars COP coefficient of performance To compute gas costs Er for the same units use Equation 9 EQUATION Erg4 10 x Cray 9 e where Crg4 cost of gas per therm dollars e efficiency of heater c Metering When water is heated with electricity the local utility rate schedule must be reviewed to determine if there are special schedules that can reduce the cost of heating water Some utilities offer reduced rates for water heaters that operate during night hours This may require Special wiring switches circuit breakers and piping all extra cost items Where utilities have on peak and off peak rate schedules it may be economically desirable to add a time switch to limit electric water heater usage to off peak hours d Control All water heater supply systems should be equipped with automatic temperature controls designed to be field adjustable for the lowest possi
62. hermostat setting or annual use Standby loss Reducing storage temperature to 95 deg F in the two lavatories will reduce standby loss to a negligible amount Therefore the standby loss for the slop sink is only considered from the second alternate 1 058 795 352 932 Btu per year 3 The total annual energy use for this alternate is the heating energy plus standby loss 5 450 526 1 638 158 352 932 7 451 616 Btu per year The annual cost would be 14 60 x 7 451 616 108 79 1 000 000 There are of course more alternatives to consider than those detailed above All of the possible alternatives their annual energy use and cost are summarized in Table A 1 3 01 66 801 vet 861 191 502 1903 9941691 9292241 221469578 28679178 ER LB8 OL 1216912 Lenuuy 18301 2 6 2SE 86486971 925095 OsL t9L l 925 097 S ZER der 861486941 2692559 SOA 06169141 26942559 266256 298 501 851 829 1 06 061 8 10N 7118 00070911488 91262272 10179199 3015 dots 501509 yrs dois suiseg 516 AA mg 5501 pueuweg Gig 421135 251 c SSAILVNSALTIV HAIVHH 40 AHVMW S T V JIVI Xue 29 t 30350 129 302350 quer 71891 30350 2621035 dois 29 wel 29 342350 300350 7179 300350
63. hers pounds kilograms of dry clothes per hour 5 gallons of water hot amp cold per pound of dry clothes 41 6 liters of water hot amp cold per kilogram of dry clothes 0 60 60 percent of total amount of water is hot water 1 3 that portion of the number of machines assumed to be drawing water simultaneously F time required to fill each machine with water minutes C number of fill cycles per hour per machine b Total heating capacity and peak demand Dpp of hot water based on the number of persons will be computed as in Equations 3 and 4 3 01 21 EQUATION Nx P x 5 0 60 gph 3a H or H Nx P x 41 6 x 0 60 Lph 3b H EQUATION Dm 5 0 60 gpm 4 H x 3 x F x C or Dre N x P x 41 6 x 0 60 Lpm 4b H x 3 x F x C where N number of persons P pounds kg of dry clothes per person or patient per week 15 pounds 7 kg per person or 35 pounds 16 kg per hospital bed 5 total gallons of water hot amp cold per pound of dry clothes 0 60 60 percent of total amount of water is hot water H number of work hours per week 1 3 that portion of the number of machines assumed to be drawing water simultaneously 41 6 total liters of water hot amp cold per kilogram of dry clothes F time required to fill each machine with water minutes number of fill cycles per hour per machine 5 Multiple water Heaters Hospitals laundry buildings
64. hquakes or other natural phenomena which may cause pipe rupture local codes shall dictate the use of automatic shutoff valves and the precautions to be taken to avoid pipe rupture d Ventilation When gas piping is run through a crawl space the crawl space shall be ventilated in accordance with DM 3 03 3 01 27 PAGE 28 INTENTIONALLY BLANK Section 6 ENERGY CONSERVATION A AIR SOURCE HEAT PUMPS a General An air source heat pump used for heating of domestic hot water includes an evaporator that extracts heat from an air stream and transfers this heat to a refrigerant This low level heat is raised to a higher usable level by compressing the refrigerant gas The higher level of heat is then transferred through a vented double wall condenser to the domestic hot water This system requires a small water circulating pump to circulate the heated water to a storage vessel and a fan to blow the heat Source air over the evaporator coil b Packaged Water Heater Heat Pump The water heater heat pump WHHP is used to save energy and must be connected to a conventional water heater for backup and storage The WHHP operates on the principle of a nonreversible heat pump the heat extracted from the air plus the heat added by the compressor the circulating pump and a blowthrough fan is transferred to the hot water The operating cost of the system is the electricity purchased to power the WHHP Depending on the evaporator s ambient air temperatu
65. ing the hot water A desuperheater is installed in the hot gas line and should be sized to desuperheat only Little or no condensing should take place If the desuperheater is oversized it can act as an uncontrolled auxiliary condenser and cause operating problems such as low head pressure low back pressure and poor expansion valve control Adequate hot water storage for the building s use must be provided for this system to work properly Water temperatures from 105 deg to 135 deg F 41 deg to 57 deg C are normal for this system The storage size will depend on building hot water use the A C unit size and its hours of operation See Figure 9 Heat Recovery A C System with Desuperheater If the capacity of the desuperheater cannot satisfy all the hot water usage it may be used as a preheater thus saving energy 3 01 42 When a desuperheater is added to the hot gas line the capacity of the A C unit decreases because of the pressure drop in the desuperheater Part of the decrease in capacity due to the pressure drop is recovered by the addition of the condenser surface of the desuperheater If pressure drop alone were used to evaluate the decrease in capacity the loss would range from 1 5 to 2 6 percent for R 12 and R 22 respectively This Design Manual cannot be definitive on the overall effect on the capacity change due to the pressure drop and the increased condenser surface therefore it is recommended that the designer review all
66. input ratings greater than 12 kW to an R value of 10 square feet multiplied by hour multiplied by deg F per Btu 1 76 meter squared multiplied by deg C per watt or to a standby loss of 13 Btu per hour per square foot 41 watts per square meter of tank surface area C Gas and Oil Fired Water Heaters Limit standby heat loss loss when the heater is not fired for water heaters rated 75 000 Btu h 22 kW or less to 67 EQUATION 2 3 5a volume in gallons or 250 S 2 3 5b volume in liters Where S is expressed in a percent per hour of stored capacity Testing shall be in accordance with the Department of Energy DOE Water Heater Test Procedures Section 430 22e in its most current form Limit standby heat loss for all gas and oil fired water heaters with input capacities greater than 75 000 Btu h 22 kW but less than 4 000 Btu h per gallon 0 3 kW liter of stored water to 67 8 A F TG 6a volume in gallons EQUATION 5 or 3 01 25 250 5 2 8 bDD lt 6b volume in liters d Recirculated Systems Hot water systems using a circulating pump will be insulated to limit the heat loss to a maximum of 17 5 Btu h per linear foot 16 8 watts per linear meter e Insulation Insulate all service hot water piping with asbestos free pipe insulation having a K value of approximately 0 27 Btu inch per hour multiplied by foot multiplied by F 0
67. ion Sufficient instrumentation should be provided to allow instantaneous determination of solar system performance including thermometers and pressure and flow measuring and indicating devices Provision should be made to allow continuous recording of temperatures pressures and flows by means of portable instruments for diagnostic purposes Where feasible energy use by the backup system should be measured with an integrating meter to allow periodic meter readings The initial and maintenance costs of this instrumentation can be expensive and need to be assessed against the size and overall cost of the proposed installation Pumps Selection of pumps should be in accordance with MIL HDBK 1003 13 Where pumps are used for fluids other than water a spare shall be provided Pressure gauges should be provided on the suction and discharge of each pump g Heat Exchangers Heat exchangers should be designed to allow ready access for cleaning and replacement Thermometers and pressure gauges with appropriate ranges should be provided to measure inlet and outlet temperatures and pressures for each fluid h Heat Transfer Fluids Double wall heat exchangers should be utilized with heat transfer fluids other than water Fluids other than water should not be used in family housing Beat transfer fluids should meet the requirements shown in the Housing and Urban Development HUD Intermediate Minimum Property Standards Supplement for Solar Heating
68. is used for short durations and in small quantities The designer must compare the cost of the heat lost from central plant storage and piping with the usually higher cost of energy and installation costs required for line heaters The designer must also include in his cost analysis the piping costs for both systems When line heaters are used no hot water pipe is required except from the line heater to the fixture When a circulating pump is used in a central system to keep the water at the fixtures hot at all times the pump must be equipped with an automatic time switch to shut it off when the facility is not occupied The circulating pump should run only during the occupied hours which requires a timer switch to be programmed for a seven day week and have skip a day features to allow for holidays etc c Modular Boilers When there is a demand for higher temperature water for short durations the modular boiler concept should be analyzed For example assume the majority of the hot water demand is for 110 deg F to 115 deg F 43 deg C to 46 deg C water but a food service area requires 180 deg F 82 deg C water for 2 hours once a day A primary boiler can heat all the water to 115 deg F 46 deg C and a second boiler acting as a booster heater can heat only that water drawn by the food service area Advantages of the modular concept are the reduction in heat loss of high temperature storage and the automatic firing of the high temp
69. logical Assumptions 10 CFR 436 14 c Code of Federal Regulations General Services Administration Government Printing Office Washington DC 20402 National Fire Protection Association Batterymarch Park Quincy MA 02269 54 84 National Fuel Gas Code 58 86 Storage and Handling of Liquified Petroleum Gases 75 81 Protection of Electronic Computer Data Processing Equipment National Standard Plumbing Code National Association of Plumbing Heating Cooling Contractors P O Box 6808 Falls Church VA 22046 1983 with supplements Naval Facilities Engineering Command NAVFACENGCOM Design Manuals DM Publications P Guide Specifications NFGS and Military Handbooks MIL HDBK Copies of DMs and P Pubs may be obtained from the U S Naval Publications and Forms Center 5801 Tabor Avenue Philadelphia PA 19120 NFGS and MIL HDBK are available to all from the U S Naval Publications and Forms Center 5801 Tabor Avenue Philadelphia PA 19120 DM 3 03 Heating Ventilating Air Conditioning and Dehumidifying Systems DM 5 02 Hydrology DM 5 03 Drainage Systems DM 5 07 Water Supply Systems DM 5 08 Domestic Wastewater Control DM 5 09 Industrial and Oily Wastewater Control DM 5 10 Solid Waste Disposal DM 33 02 Naval Regional Medical Centers Design and Construction Criteria MIL HDBK 1008 Fire Protection for Facilities Engineering Design and Construction MIL HDBK 1003 13 Solar Heating of Buildings and Domes
70. m shall maintain the predetermined pressures water levels and air water ratio within the tank When duplex pumps are provided controls shall start only one pump at a time Pumps shall be operated alternately and shall run simultaneously only when the predetermined low pressure cannot be maintained by a single pump Controls shall admit compressed air into the tank only when tank pressure at high water level is below normal b Booster Pumps Booster pumps may be the on off type or continuous running type 3 01 13 1 On Off Type The installation of an on off type of pumping system should be considered when relatively long periods of pump on or pump off is anticipated Pumps shall be activated only when pressure is inadequate by a sensing device located in the pump suction line Flow normally will be through a full size pump bypass having a check valve with two normally open isolating valves Whether the installation has one pump or multiple pumps only one bypass shall be provided Each pump shall be provided with isolating valves 2 Continuous Running Variable speed constant pressure continuous running pumps shall be considered when anticipated pressure fluctuation would result in short cycling of the on off type of pumps Whether the installation is a single pumpeor multiple pumps only one full size pump bypass with a gate valve normally closed shall be provided Each pump shall be provided with isolating valves 3
71. ng storage capacity is small or nonexistent additional new storage sized for the project may be required 1 retrofitting of an existing water heater system requires the repiping of the cold water into the WHHP and then back to the existing water heater Some existing water heaters and some new ones have no more than two connections one hot and one cold and some have an anode or other obstruction in one of the connections The installation of the WHHP may require a special fitting on the water heater to make the system work properly The designer must verify the need for these special requirements 2 Prior to the retrofit installation sludge and particulate matter must be removed from the existing water heater and piping system to prevent damage to the WHHP and its piping Water pipes between the heat pump unit and the tank must be insulated to maximize savings The cold and hot water pipes should not be installed in a common insulation jacket 3 01 32 3 The power source for the WHHP must be investigated to ensure that there is adequate power available and that the voltage and phase are correct Some WHHP units require 115 volt single phase power for their small circulating pumps and 208 or 220 volt single phase power for their compressors Some of the larger compressors require three phase power e Geographic Influence The air source WHHP must be equipped with a low ambient air thermostat to prevent its operation below 45 5
72. nominal 40 hour week use or less than 118 000 Btu s per square foot per year 1340 MJ mL2J a around the clock use b General sizing Heating and storage capacities shall be calculated in accordance with Table 6 For an example of calculation procedures see Example 2 For estimating hot water requirements for a facility when the type and number of fixtures are not known Table 7 shall be used For water heater capacities for one and two family living units See Table 8 c Sizing for hospitals See NAVFAC DM 33 Series d Example 2 Calculate the hot water requirements in accordance with Table 6 of an enlisted men s barracks with subsistence facilities All water is to be heated and stored at 140 deg 60 deg C A booster heater will be provided to boost water temperature from 140 deg F to 180 deg F 60 deg C to 82 2 deg C for dishwashing and utensil washing incoming water is at 70 deg F 21 1 deg C Fixtures outside of kitchen area 30 lavatories public 8 30 L 240 gph 908 L hr 6 lavatories private 2 7 6 L 12 gph 45 L hr 30 showers 150 568 L 4 500 gph 17 032 L hr 8 clothes washers 25 95 L 200 gph 757 L hr 6 service sinks 20 76 L 120 gph 454 L hr 3 laundry stationary tubs 25 95 L 75 284 L hr TOTAL 5 147 gph 19 480 L hr 3011515 40322j puewap 03 5 VEH wesbol Ly 99 4 1 punod 199 95 MOLLY UMOLY S
73. ns per minute Second Alternate Mini Tank Heaters Three heaters will be required One is needed for each lavatory 2 basins each and one is needed for the slop sink The units will be always on and set for 140 deg F with a tampering valve to supply tepid water for the basins ad 120 deg F water for the slop sink Heating energy for each lavatory 2 basins E 8 3 x Gx T SS e 8 3 x 37 1 2 x 250 gal yr 95 45 0 95 9 828 946 Btu per year Heating energy for slop sink 8 3 x 10 x 250 120 45 0 95 1 638 158 Btu per year Standby losses No data have been published for standby losses from small 1 gallon heaters An estimate can be made using the following ratio of tank surface areas 3 01 63 30 gallon tank 3391 square inches 1 gallon tank 297 square inches lavatories and slop sink 3 units st at 140 deg F 3 460 Btu per hour x 24 x 365 x 297 3391 1 058 795 Btu per year The total annual energy use for this alternative is then heating energy plus standby loss 9 828 946 1 638 158 1 058 795 12 525 899 Btu per year The annual cost in this case would be 14 60 x 12 525 899 182 88 1 000 000 and the savings for the first year would be 167 88 182 88 15 00 per year INCREASE 27 657 321 12 525 899 15 131 422 Btu per year DECREASE This alternative does not present the greatest potential for energy savings Restriction of water flow would reduce hot water u
74. nside of a building shall be selected in accordance with the Testing and Rating Procedure for Grease Interception PDI G101 3 Fixtures Requiring Grease Interceptors Grease interceptors shall be provided to receive the wastes from pot sinks pre wash sinks dishwashers without pre wash sections and soup kettles Interceptors shall not be installed to accommodate kitchen fixtures in private living quarters 3 01 6 Cu Chemical Wastes Wastes containing acids or other chemicals which can adversely affect the piping system may require treatment prior to being discharged into the sanitary drainage system 1 Treatment Treatment may be inside or outside of a building and shall consist of dilution or neutralization by running the chemical wastes through a treatment sump Wastes with low chemical concentrates may be run directly into the sanitary sewer when sufficient dilution will occur within the piping system as a result of mixing with other wastes For additional criteria on treatment of chemical wastes see NAVFAC DM 5 08 and DM 5 09 2 Piping Piping conveying chemical wastes to areas of treatment shall be of a material highly resistant to the chemical being conveyed d Backwater Valves Backwater valves shall be provided where required to protect areas within the building from being flooded as a result of overloads or of surges within the system When a combined sanitary storm Sewer is encountered all areas of the building located
75. ntakes and exhaust outlets properly to enclose the WHHP to reduce the noise transmitted to occupied spaces and to increase the availability sources of replacement parts The WHHP must have its condensate drain piped to a floor drain or to the outside of the building The fan moving air over the evaporator generates noise that must be suppressed to eliminate noise problems in adjacent occupied spaces If the WHHP is located where the evaporator air is drawn from an area laden with lint leaves dust or other airborne material the designer must provide air filtration The designer must specify a manual lock type switch to permit the manual selection by authorized people of either the WHHP or the backup heat source in the event the WHHP is not usable a Under emergency operation the controls must shut off the WHHP and transfer the water temperature control to the backup heater If the temperature of air entering the evaporator drops to 45 50 deg F 7 10 deg C the WHHP should automatically shut off to allow the backup water heater to heat the water b The designer must determine the hardness of potable water in the area where the WHHP will be installed and specify the necessary water softening equipment to prevent scale formation in the double wall condenser heat exchanger d Retrofit Any existing domestic water heater can become the storage and backup heater when retrofitted with a WHHP as the source for the hot water If the existi
76. of a WHHP g Exhaust Air Exhaust systems are a good source of relatively constant temperature air for a WHHP if the dry bulb temperature does not exceed 125 deg F In most naval facilities toilet room exhaust fans are running whenever a building is occupied which is the time hot water is needed This type of installation requires the WHHP to be mounted near the exhaust duct to minimize resistance in the evaporator duct connection No attempt should be made to use exhaust air from range hoods fume hoods etc as a heat source because of the contaminants or corrosives in the air See Figure 4 Exhaust Air Heat Pump 2 WATER SOURCE HEAT PUMPS a Condenser Water Source A packaged water source heat pump operates the same as an air source heat pump except that water instead of air is the source of heat A facility that has water cooled air conditioning equipment that is required to run during occupied hours has a ready source of heat for such a heat pump The heat normally rejected to the atmosphere can be used to heat the service hot water See Figure 5 Water to Water Heat Pump Efficiency With condenser water temperatures in the 60 deg F to 75 deg F 16 deg C to 24 deg C range the COP of the heat pump can be as high as 4 5 The designer must provide some sort of head pressure regulation to protect the heat pump from damage due to high temperature condenser water 3 01 35 Cooled Exhaust Air Evaporator Water to Building Doubl
77. on Circulation shall be at a rate that will limit the water temperature drop to 20 deg F 6 7 deg C maximum temperature difference between supply and return A method which has proved satisfactory and is generally accepted for determining rate of circulation is to allow 1 gallon 3 8 liters per minute for each 20 fixtures using hot water 3 Valves Valves for balancing the circulation shall be provided in each return branch 4 CHILLED DRINKING WATER SYSTEMS a Types of Units Chilled drinking water may be provided by self contained cooler fountains or by a central refrigeration unit from which chilled water is piped to multiple drinking fountains Self contained units shall be provided unless a piped system with a central refrigeration unit can be justified economically Units shall be provided in accordance with DoD 4270 1 M Construction Criteria Manual b Design The design of chilled drinking water systems shall be in accordance with the procedures outlined in the American Society of Heating Refrigerating and Air Conditioning Engineers Inc ASHRAE Handbook 1983 Equipment 301 23 STORAGE HEATER INDIRECT HEATER GAS OR ELECTRIC STEAM SOILER COMBINATION TRV RV INDIRECT HEATER HW HEATER GAS COAL OR COAL STOKER OR GAS COLD WATER CW PRESSURE RELIEF HOT WATER HW VALVE HOT WTR CIRC HWC TEMPERATURE pans GATE VALUE RELIEF VALVE BL CHECK VALVE 0 THERMOMETE
78. on a comparative basis if a point of use heater will offer benefits Separate analysis of each opportunity is a necessity because of the variations in water heater prices and regional energy costs Two sample calculations are shown in this Appendix and should provide the reader with sufficient guidance for making his own calculations b The two examples to be used for illustrating energy analysis and life cycle costing include Office building lavatories and slop sinks retrofit Flight training facilities lavatories and slop sink new construction c Office Building Lavatories Retrofit Example Assume in this example a 35 year old two story barracks building which has been converted to low density office space The old shower stalls are not required There is one lavatory on each of the two floors plus one slop sink Each lavatory contains six basins but four have been disconnected Building occupancy is 25 persons eight hours per day five days per normal week 250 total days per year Hot water to the two lavatories and slop sink is supplied by an oil fired 30 gallon heater with thermostat set at 120 deg F Groundwater temperature averages 45 deg range 35 deg F 55 deg F Fuel oil costs 0 85 per gallon which is equal to 6 07 per 1 000 000 Btu Electricity is billed at 0 050 per kWh or 14 60 per 1 000 000 Btu We will compare instantaneous and small tank point of use heaters to the existing circumstances The first s
79. oning Suction Line Air Handler To Floor Drain Liquid Line Regulator Liquid Solenoid Valve Hot Gas Regulator Float Switch Heat Recovery Temperature Control FIGURE 8 Heat Recovery A C System With Auxiliary Condenser 2 01 41 The hot gas regulator 3 bypasses hot gas to the receiver to maintain head in the receiver during start up and during the heat recovery mode It is closed by a solenoid valve during the cooling only mode The float switch 4 operates to maintain a liquid level that prevents hot gas from blowing through the condenser As the liquid level rises the float valve cycles the liquid solenoid valve 2 to maintain the liquid level The heat recovery temperature control 5 cycles the air cooled condenser fans in response to the heating demand As the leaving domestic hot water temperature drops indicating an increased load the fans cycle off saving energy and decreasing the heat rejected to the atmosphere A hot water flow Switch is used to place the entire control system into a heat recovery mode when there is a demand for hot water The designer must insulate all hot gas lines outside the building and must design refrigerant piping to drain oil back to the compressor from vertical hot gas lines This system requires additional refrigerant as compared to a standard air conditioning system because of the receiver water cooled condenser liquid level and the liquid refrigerant held up in the air cooled condenser and t
80. ous heater This type of heater is required in facilities where higher temperature water say 180 deg F 82 deg C is needed and is not available from the building hot water system To conserve energy the booster heater should be installed as close as possible to the fixture requiring the higher temperature water sized conservatively set to produce the lowest acceptable temperature and have little or no storage capacity Dishwashers in public and subsistence facilities require hot water at 180 deg F 82 deg C for rinsing Dishwashers in family housing can use 110 deg F 43 deg C water if good low temperature dishwashing detergents are used The contents are sanitized by the electric drying cycle rather than a hot water rinse Another option the designer may choose is to specify a dishwasher with a booster heater to heat the rinse water to a higher temperature 3401 51 b Line Heaters The use of a central water heater system is not generally advised if individual fixtures or small fixture clusters are widely separated and remote from the proposed water heat location The heat loss in the storage tank and the hot water distribution pipes is inefficient and can in some systems equal or exceed the energy required to heat the hot water actually used Line heaters located at the fixtures eliminate these losses and are particularly applicable in office buildings industrial plants hobby shops and schools where only low temperature water
81. p across the device as flow varies As the flow rate tends to increase the increased pressure drop causes the cup to move and cover up more holes the reverse takes place as the flow rate decreases The result is a limit to flow rate through the device independently of pressure variations of the supply system The flow rate of the device is factory set by selecting the proper cup and spring for a given flow rate 1 Flow Rate The flow rate should be limited to 0 5 gpm 1 9 Lpm maximum for public and private lavatories and to 3 gpm 11 34 Lpm for showers and kitchen sinks when the supply pressure is 80 psig 550 kPa or below 2 Water Pressure Some water utilities and base water systems have street pressures in excess of 80 psig 550 kPa Where this condition exists the pressure should be reduced by a pressure reducing valve to no more than 80 psig 550 kPa inside the building If the building requires a booster house pump gravity water tank or a hydropneumatic system the maximum pressure should be limited to 80 psig 550 kPa b Automatic Valves Automatic shutoff hot water valves in addition to the flow regulators should be analyzed for use in public commercial and office buildings These valves do not in themselves ensure a reduced use of hot water In some cases the use of hot water is greater but they do eliminate the chance of a tap being left open and wasting hot water 11 COST OF ENERGY a Evaluation The analysis of
82. piping from city water pressure and draining it using one or more valves The solar collectors and associated piping must be carefully sloped and vented to drain the collectors exterior piping This type of system is exposed to city water pressures and must be assembled to withstand test pressures as required by local code Pressure reducing valves and pressure relief valves are required when city water pressure is greater than the working pressure of the collectors One or two tank storage systems can be used Scale deposits and corrosion can occur in the collectors with hard or acidic water 4 Drain Back Systems Drain back systems Figure 10 are generally indirect water heating systems that circulate treated or untreated water through the closed collector loop to a heat exchanger where its heat is transferred to the potable water Circulation continues until usable energy is no longer available When the pump stops the collector fluid drains by gravity to a reservoir or drain back tank In a pressurized system the tank also serves as an expansion tank when the system is operating and must be protected from excessive pressure with a temperature and pressure relief valve In an unpressurized system the tank is open and vented to the atmosphere Since the collector loop is isolated from the potable water valves are not needed to actuate draining and scaling is not a problem collector array and exterior piping must be sloped to
83. re relative humidity and the temperature of leaving hot water the ratio of the total heat transferred to the water can be as much as 2 to 4 times the energy heat input to the WHHP This means that for each unit of purchased energy heat 2 to 4 times that amount of heat will be transferred to the water The difference between purchased heat and the heat in the water is the heat extracted from the air by the evaporator 1 Coefficient of Performance COP Heat pumps are rated in Btu h kWh of capacity and in COP The COP of a packaged WHHP is the total amount of heat transferred to the hot water divided by the heat input of the compressor fan and pump motors energy output in Btu h kWh EQUATION 7 energy input in Btu h kwh 2 System A water heating system will include the packaged WHHP a storage tank a backup heating source and controls for automatic operation See Figure 2 Air Source Heat Pump c Sizing Section 3 of this design manual shall be used to determine the required storage capacity and the hot water demand for a project The practical maximum water temperature that a WHHP can produce is 135 deg F 57 deg C If the temperature rises above 135 deg F 57 deg C the COP of the unit can fall below 2 making the unit uneconomical for heating water When water temperatures above 135 deg F 57 deg C are required booster heaters shall be used 3 01 29 Double Wall Condenser Heat Exchanger Ins
84. rvice n b Water Hammer Arrestors vii GA GA C C GA GA WWW w Page 01 1 01 1 01 1 01 1 01 2 01 2 01 2 01 2 01 5 01 5 01 5 01 7 01 7 01 7 01 7 01 8 01 8 01 8 01 8 01 8 01 8 01 8 01 8 01 10 01 10 01 11 01 11 01 11 Section 4 Section 5 BOOSTER SYSTEMS AND PUMPS a Hydro Pneumatic System b Booster Pumps HOT WATER SYSTEMS a Water Temperatures b Water Heaters c Hot Water Circulation CHILLED DRINKING WATER SYSTEMS a Types of Units b Design INSULATION OF PLUMBING SYSTEMS HOT WATER SYSTEMS a Unfired Water Storage b Electric Water Heaters m c Gas and Oil Fired Water Heaters d Recirculated Systems e Insulation MISCELLANEOUS SYSTEMS Cold Water Heating System Rainwater Conductors Freezing Temperatures Design FUEL GAS SYSTEMS DESIGN SAFETY PRECAUTIONS System Pressure Pressure Regulator Location Seismic Consideration Ventilation viii Ww Ww WWW CO CO Page 01 25 01 25 01 25 01 26 01 26 Ww WWW GA CO WWW w 01 26 01 26 01 26 01 26 01 26 01 27 01 27 01 27 01 27 SECTION 6 ENERGY CONSERVATION AIR SOURCE HEAT PUMPS General Packaged Water Heater Heat Pump Sizing Retrofit sx Geographic Influence Equipment Location Exhaust Air W
85. s throughout the year and high energy costs for water heating 2 System Types Selection of system types should be based on geographic location quantity of hot water required time of day when the hot water is used type and size of hot water storage water quality and the ability of local maintenance forces a Advantages and Disadvantages Each type of system in each location will have advantages and disadvantages as described in Paragraph 5a that must be evaluated in conjunction with performance and economics b Criteria Since the performance of solar systems is very dependent on the magnitude and time of hot water use good estimates or measurements of hot water use should be obtained for similar buildings C Performance The expected performance of solar hot water systems should be evaluated for each specific application in comparison with other hot water systems 1 Energy Savings The energy savings from a solar hot water system should be determined by using the appropriate method in Chapter 40 of the ASHRAE Handbook 1984 Systems the ASHRAE Solar Heating of Domestic and Service Hot Water Manual or MIL HDBK 1003 13 Solar Heating of Buildings and Domestic Hot Water 3 01 47 2 Temperature Since the performance of solar hot water systems is dependent on hot water temperature the designer must determine the lowest temperature at which it is possible to generate and store hot water for use In the absence of other ac
86. sage would permit consideration of two different types of point of use heaters and would reduce the cost of installing the mini tank standby losses We have assumed a 2 1 2 gallon per minute flow rate and 3 gallons per person per day Flow rate may be restricted to 1 2 gallon per minute with an aerator at lavatory basins This has been estimated to reduce per person per day usage to 2 gallons Slop sink flow rate can be reduced to 1 1 2 gallons per minute but this would not affect the 10 gallons per day used for janitorial purposes The age of the plumbing fixtures in the building is such that faucets must be replaced to allow the attachment of flow restricting aerators Third Alternate Instantaneous Heaters with New Faucets Remember that three heaters will be required and that we must design for simultaneous operation of 2 faucets at the lowest annual groundwater temperature Heating energy for each lavatory 3 0 16 1 2 1 2 95 35 9 6 kW 3 01 64 Check maximum temperature one faucet case at highest groundwater temperature R 0 16 Ke 9 6 0 16 1 2 55 T ro gt 175 deg F It is obvious that this is a highly dangerous temperature for a wash basin and therefore one instant heater cannot serve 2 basins at the extremes of usage 1 basin 2 basins and the extremes of groundwater temperature 35 deg F 55 deg F One 4 8 kW heater must be used each of the 4 basins
87. stem Figure 10 is an indirect water heating system that circulates air through the collectors via ductwork to an air to liquid heat exchanger There its heat is transferred to the potable water which is pumped through the tubes of the exchanger and returned to the storage tank Circulation continues as long as usable heat is available An air system can use single or double storage tank configurations The two storage tank system is used most often since air Systems are generally used for preheating domestic hot water and may not be capable of reaching 120 to 160 deg F 49 to 71 deg C delivery temperatures Air does not need to be protected from freezing or boiling is non corrosive and is free However air ducts and air handling equipment need more space than piping and pumps Ductwork is very laborious to seal and air leaks are difficult to detect Power consumption is generally higher than that of a liquid system because of high collector and heat exchanger static pressure loss All dampers installed in air systems must fit tightly to prevent leakage and heat loss Dampers might be needed in the collector ducts to prevent reverse thermosiphoning at night which could freeze the water in the heat exchanger coil No special precautions are needed to control overheating conditions in air systems b Applications 1 Building Types Solar hot water systems should be considered for buildings having relatively large hot water requirement
88. surface water to a level below the lowest floor Drain may be perforated or open joint pipe and may be connected to the building storm sewer or spilled into a sump from which it may be pumped to storm sewer or outfall If directly connected to a storm sewer sub soil drain shall be protected by an accessible backwater valve d Piping System The storm drainage piping system shall be independent of any other piping system Drains which are too low for gravity flow shall be drained into a sump where the effluent will be pumped For criteria on sump pumps see paragraph 1 Sanitary Systems 3 COMBINED SANITARY AND STORM DRAINAGE SYSTEM a System Layout When a combined drainage system is to be provided the systems shall be maintained as separate systems within the building Systems shall be combined outside of the building and preferably at a manhole b Backflow Drains from the lower floors especially drains from areas which are located below grade and may be subject to backflow shall be equipped with accessible backwater valves 3 01 8 SUL S P 01 Ge egt 9 ues OEL 6 Som lo 071 575 24990 001 ueptJ us 081 5 2 061 9 BLO StL 574 uu K u2 051 5 5 071 S S A313 S3 081 S Lu 081 uo35t
89. tem has an impact on the sizing of boilers or when electricity is used appropriate means should be provided to limit the heating capacity 2 Component Selection Components of solar systems should be selected to provide reliable long term performance Where packaged or predesigned systems are utilized they should meet the requirements of ASHRAE Standard 95 1981 Methods of Testing to Determine the Thermal Performance of Solar Domestic Hot Water Systems a Collectors Solar collectors should be tested in accordance with ASHRAE Standard 93 77 Methods of Testing to Determine the Thermal Performance of Solar Collectors b Storage Storage systems should be tested in accordance with ASHRAE Standard 94 77 Methods of Testing Thermal Storage Devices Based on Thermal Performance Insulation of storage systems should be in accordance with Section 4 of this manual The designer must perform an energy and economic evaluation to determine if additional insulation is warranted Storage tanks should be located so they are completely accessible for inspection and maintenance Means for routine drainage of storage piped to a floor drain should be provided c Backup System Selection of the backup system should be in accordance with Section 3 of this manual d Controls Selection of controls should provide automatic unattended fail safe operation Provision should be made for regular adjustment and calibration 3 01 49 e instrumentat
90. tep is to determine the size of point of use heaters required for each lavatory and slop sink The temperature required is 95 deg F tepid at each lavatory and 120 deg F at the slop sink Water usage is determined as follows Lavatory 2 1 2 gal min 3 x 25 gal day 1 basin flow rate per basin total for 4 basins slop sink 3 3 4 gal min 10 gal day flow rate Each lavatory will require one heater whose maximum flow rate will be 2 1 2 2 1 2 5 gallons per minute The temperature must be based on the lowest annual groundwater temperature to meet the mandated tepid water requirement Further the temperature at the highest annual groundwater temperature should not exceed 120 deg F to guard against scalding 3 01 61 R 0 16P Tri F 2 x 2 1 2 5 since one heater must occasionally supply 2 faucets 0626 95 35 48 kw No commercial 50 kW heater was found in this example largest unit found was 20 kW It is obvious that a straightforward retrofit with off the shelf instantaneous heaters is not possible An alternative involving flow restrictors will be considered later on because the required 60 deg F minimum rise at 5 gallons per minute cannot be achieved with instant heaters The correct size for a mini tank heater cannot be calculated from available information and manufacturers representatives must be consulted A maximum 5 gallons per minute flow rate and 38 gallons per day can easily be met
91. tic Hot Water 3 01 74 NFGS 15400 Plumbing 89 Engineering Weather Data 442 Economic Analysis Handbook Plumbing and Drainage Institute 5342 Boulevard Place Indianapolis IN 46208 PDI G101 85 Testing and Rating Procedure for Grease Interceptors PDI WH201 77 Water Hammer Arrestors Uniform Plumbing Code International Association of Plumbing and Mechanical Officials 5032 Alhambra Avenue Los Angeles CA 90032 1982 Water Heater Test Procedures 430 22e Department of Energy DOE 1000 Independence Avenue SW Washington DC 20585 3 01 75 U S GOVERNMENT PRINTING OFFICE 1987 175 983
92. tilize as much as 96 percent of the total energy input to the engine See Figure 11 Cogeneration Heat Recovery 1 Capacity The designer must not oversize the electric generator for the sake of satisfying the building s electrical needs unless the cost of the generated electricity is less than that of the purchased power The unit must be sized so the heat rejected is approximately the same as or less than the hot water requirements to make this system efficient and cost effective 2 Protection When this system is used in climates with freezing temperatures glycol should be used in the nonpotable piping system outside the building or the water lines must be traced to prevent freezing Glycol cannot be used in potable water systems 3 Cost Because of the high capital cost of this system a life cycle cost analysis must be made based specifically on the building under study using NAVFAC P 442 Economic Analysis Handbook procedures 4 Equipment The packaged cogeneration unit consists of engine using natural gas propane or diesel fuel driving an electric generator The designer is required to design the piping from the backup water heater storage and the cogeneration unit the electrical connections Switchgear fuel lines and fuel storage if required The designer is also required to meet local codes and satisfy the utility company s requirements b Stand Alone System In sizing a stand alone system the building s
93. tion systems are practical only in areas where freezing is infrequent Freeze protection for extreme weather conditions is provided either by recirculating warn water from the storage tank or by flushing the collectors with cold water Direct water heating systems should not be used in areas where water is extremely hard or acidic Scale deposits may quickly obstruct or corrode the absorber fluid passages This type of system is exposed to city water line pressures and must be assembled to withstand test pressures as required by local code Pressure reducing valves and pressure relief valves are required when the city water pressure is greater than the working pressure of the collectors A recirculation system often uses a single storage tank for both solar energy storage and the auxiliary water heater but a two tank storage system can be used 3 01 44 TOLWLEC TORS BACH PATER LEVEL OPERATIONAQ WATER gt EXPANSION TANK SIOASCE TANK Drain Down System Air System FIGURE 10 Typical Solar Systems 3 01 45 3 Drain Down Systems Drain down systems Figure 10 are pumped circulation direct water heating systems that circulate potable water from storage to the collector array where it is heated Circulation continues until usable solar heat is no longer available When a freezing condition is anticipated or a power outage occurs the system drains automatically by isolating the collector array and exterior
94. tors Heating Ventilating Conditioning and Dehumidifying Systems Refrigeration Systems for Cold Storage Compressed Air and Vacuum Systems Central Heating Plants Fossil Fuel Power Plants Exterior Distribution of Utility Stern HTW CHW Fuel Gas and Compressed Air Elevators Escalators Dumbwaiters Access Lifts Pneumatic Tube Systems Noise and Vibration Control of Mechanical Equipment Diesel Electric Generating Plants Industrial Controls Solar Heating of Buildings and Domestic Hot Water Power Plant Acoustics Air Pollution Control Systems for Boilers and Incinerators Thermal Storage Systems Industrial Ventilation Central Building Automation Systems Air and Section 1 Section 2 4 Section 3 5 PLUMBING SYSTEMS PLUMBING CRITERIA SCOPE CANCELLATION RELATED CRITERIA POLICY a Economy b Reliability 2 0 Material and 40 Protection of Computers Other Esudment E Water Damage DRAINAGE SYSTEMS SANITARY SYSTEMS Sumps and Sump Pumps Interceptors Chemical Wastes Backwater Valves Food Waste Grinders Floor Drains STORM DRAINAGE SYSTEM General Downspouts Sub Soil Drains Piping System COMBINED SANITARY AND STORM DRAINAGE SYSTEM a System Layout b Backflow 2 2 2 P Traps in PESE Se VENTING OF THE DRAINAGE SYSTEMS WATER SUPPLY SYSTEMS PIPING SYSTEMS a Water Se
95. uiated T P Relief Valve Hot Water Union Service Valve to Building 1 Fan r Evaporator T T P Capillary Tube Relief Evaporator Air ae Compressor To Fioor Drain Cold Vater Drain Packaged Water Heater Heat Puan FIGURE 2 Air Source Heat Pump 1 Recovery The heat recovery rate or heating capacity of a WHHP varies depending upon the dry bulb temperature and relative humidity RH of the air and the temperature of the heated water For example at a constant supply water temperature of 135 deg F 57 deg C a air temperature of 50 deg F 10 deg C and an RH of 25 percent a WHHP may produce 1000 units of heat At 135 deg F 57 deg C water temperature 90 deg F 32 deg C air temperature and a 65 percent RH the same WHHP can produce 1960 units of heat The impact of the heating capacity change due to a change in leaving water temperature while the air temperature remains constant is shown by carrying this example further The heating capacity of a unit with water at 135 deg F 57 deg C air at 90 deg F 32 deg C and 65 percent RH is 1960 units of heat At 115 deg F 46 deg C water temperature and the same air conditions the heating capacity is 1972 units of heat The heating capacity of a WHHP is affected more by changes in the evaporator s ambient air temperature than by changes in the heated water temperature See Figure 3 Typical WHHP Performance 2 Temperat
96. ultaneously when one pump cannot handle the flow See NAVFAC DM 5 09 d Alarms A high water alarm actuator shall be installed within sump and shall operate on audible or visual alarm when the normal high water level within sump has been exceeded e Capacity Pump capacity in gallons per minute liters per second shall be 1 1 2 to 2 times the inflow to the sump For minimum capacities of ejectors serving toilet facilities see Table 1 Interceptors Interceptors shall be provided to separate grease volatile liquids sand hair and plaster from liquid wastes when those ingredients would create a fire or explosive hazard within the system or adversely affect the operation of the system Interceptors may be of the prefabricated type or field fabricated type 3 01 5 TABLE 1 Sewage Ejector Capacities aoa Gas L No of water Cap of each No of water Cap of each closets 14 pump gpm L s 414 1 114 pump gpm L s 24 1 50 3 2 11 to 14 200 12 6 2 75 4 7 15 to 20 250 16 0 3 4 100 6 3 21 to 25 300 19 0 5 or 6 125 8 0 26 to 30 350 22 0 7 to 10 150 9 5 lt 1 Includes a reasonable number of fixtures such as lavatories urinals showers etc which are part of a normal installation 2 Pump capacities shall
97. um allowable working pressure of the equipment The temperature relief valve shall be of ample capacity to prevent the water temperature from exceeding 210 deg F 99 deg C c Location Temperature relief valves or combination temperature pressure relief valves shall be installed in the hot water outlet of an instantaneous heater or at the top of a storage tank with the thermal element located within the top 6 inches 152 mm of the tank Pressure relief valves shall be installed in the cold water inlet to the heater No valves shall be installed between the relief valves and the equipment being protected For typical installations of relief valves see Figure 1 7 Vacuum Breaker A vacuum breaker shall be provided on a copper lined storage tank to prevent the creation within the tank of a vacuum which could cause loosening of the lining c Hot Water Circulation A hot water circulation system ensures instant hot water at the fixtures and promotes water conservation In addition to circulation through the piping system circulation is induced through the storage tank thereby preventing water stratification within the storage tank and in effect increasing the amount of available hot water 1 Application A forced circulation system shall be provided when the pipe run from storage tank to the farthest fixture exceeds 100 feet 30 5 meters or when the hot water storage is in excess of 200 gallons 757 liters 2 Rate of Circulati
98. ure To obtain the maximum efficiency from the WHHP System the hot water should be kept at as low a temperature as possible Almost all hot water needs other than for dishwashing medical facilities ad some special requirements can be handled with 105 deg F to 110 deg F 41 deg C to 43 deg C water temperature In the rage of 70 deg F to 85 deg F air temperatures the WHHP heating capacity increases approximately 600 Btu h 0 176 kWh as the water temperature drops from 135 deg F 57 deg C to 115 deg F 46 deg C There are small changes in capacity at higher air temperatures and larger changes at lower air temperatures See Figure 3 Typical Performance 3 01 30 LLLLLLLLLLLLLT NS TIU ea E ipo ac 20x LJ 214224 58550 At 80 RH 019 ELM RES REAR EAE E 60 DRY BULB TEMPERATURE F C OF AIR ENTERING EVAPORATOR FIGURE 3 Typical WHHP Performance 301 31 3 Installation The designer must locate the WHHP whore there is adequate space for service and must provide clearances as required by the manufacturer to obtain maximum heating efficiency The location of the WHHP relative to the storage tank influences the size of the interconnecting water pipe The circulating pump in the WHHP is small and has a low head capability therefore the closer the two components are the smaller the pipe size will be A separate WHHP and storage tank are used to allow the designer to locate air i
99. use natural convection to transport it from collectors to storage They are applicable in climates where freezing is infrequent or for summer only use in colder climates Pressure reducing valves are required when city water pressure is greater than the working pressure of the collectors In a thermosiphon System the storage tank must be elevated above the collectors which sometimes requires designing the upper level floor and ceiling joists to bear this additional weight Also extremely hard or acidic water can cause scale deposits that obstruct or corrode the absorber fluid passages 3 01 43 Conditioned Air Condenser Water to Space Cooling Tower Evaporator SS Valve Condenser Double Wall Desuperheater Hot Water to Hot Water Building Circulator To Floor Drain Heater Bali Velve FIGURE 9 Heat Recovery A C System with Desuperheater Since thermosiphon flow is induced whenever there is sufficient sunshine these systems do not need pumps Reverse thermosiphoning must be eliminated by using a low pressure drop check valve or thermally actuated check valves 2 Recirculation Systems Recirculation systems Figure 10 are direct water heating systems that pump potable water from storage to the collectors when there is enough solar energy available to warn it and then return it to the storage tank until needed Since a pump circulates the water the collectors can be mounted either above or below the storage tank Recircula
100. veys of the availability of new materials and construction methods and from selection of the best design practices of the Naval Facilities Engineering Command other Government agencies and the private sector This manual uses to the maximum extent feasible national professional society association and institute standards in accordance with NAVFACENGCOM policy Deviations from these criteria should not be made without prior approval of NAVACENGCOM Headquarters Code 04 Design cannot remain static any more than can the naval functions it serves or the technologies it uses Accordingly recommendations for improvement are encouraged from within the Navy and from the private sector and should be furnished to Commander Pacific Division CODE 406 Naval Facilities Engineering Command Pearl Harbor HI 96060 This publication is certified as an official publication of the Naval Facilities Engineering Command and has been reviewed and approved in accordance with SECNAVINST 5600 16 J P JONES Rear Admiral CEC U S Navy Commander Naval Facilities Engineering Command MECHANICAL ENGINEERING DESIGN MANUALS AND MILITARY HANDBOOKS Number DM 3 01 MIL HDBX 1003 2 DM 3 03 DM 3 04 DM 3 05 DM 3 DM 3 DM 3 06 07 08 DM 3 09 10 DM 3 1 DM 3 11 DM 3 12 MIL HDBX 1003 13 DM 3 14 DN LD 4a x DM 3 16 MIL HDBX 1003 17 DM 3 18 Tri Service Manual Title Plumbing Systems Incinera

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