A.O. Smith NW 37-670 Instruction Manual
Contents
1. no no TO TO TO TO 5 5 5 5 5 5 6 2 6 2 6 2 6 2 6 2 6 2 8 2 8 2 8 2 8 2 8 2 8 2 8 2 8 2 8 2 8 2 8 2 8 2 8 2 8 2 NOTE For boilers 3400KW to 6000KW consult factory All fittings under 4 will be threaded type All fittings 4 and larger will be flanged Where overall height is a problem a larger diameter vessel with a reduced height may be furnished 3 ELECTRICAL RECOVERY DATA WATER BOILER SPECIFICATIONS Model Number Gal Std KW BTU Output Gal Hr Number of Number of Standard Number Amperage 3 Phase Input 100 F Rise Elements Steps and KW of Steps 208v 240V 480V 575V 80 a4 8 08 q 204 720 255 975 307 170 358 365 409 560 511 950 614 340 1 60 1 75 3 30 3 30 1 15 4 30 5 30 2 30 3 60 1 30 4 60 1 228 680 1 331 070 1 433 460 1 535 850 1 638 240 1 843 020 2 047 800 2 252 580 2 457 360 2 662 140 2 866 920 9 90 1 30 3 071 700 10 90 3 276 480 8 90 2 120 3 481 260 6 90 4 120 3 636 040 4 90 6 120 3 890 820 2 90 8 120 6 60 1 30 7 60 7 60 1 30 8 60 2 90 PIT 8 120 2 150 4 120 6 150 10 150 6 90 9 120 2 90 13 120 Not Recommended Not Recommended 13 120 2 150 9 120 6 150 5 120 10 150 7 986 420 18 120 2 90 8 395 980 18 120 2 150 8 805 540 14 120 6 150 10 120 10 150 9 624 660 6 120 14 150 10 034 220 2 120 18 150 NOTE For boilers 3000KW to 6000KW consult factory MODEL AND RATING PLATE A O SMITH CORP C P D R2. and includes typical wiring diagrams All circuits are designed for 60 or 50 Hertz alternating current Refer to ELECTRICAL CONFIGURATION TABLE below and wiring diagram provided with your boiler before completing connections to electrical supply NOTE Wiring diagrams in this manual are typical examples The specific wiring diagram for your boiler is the one supplied with the boiler Control Circuit All control circuits are operated on single phase 120V Atransformer is used in the control circuit Control circuit wiring is 14 Awg THHN or THWN type rated 600 volts 105 C Seperate instructional literature is provided with the boiler for the modulating solid state step control Portion of Table 310 16 Allowable Ampacities of Insulated Aluminum and Copper Clad AluminumConductors Portion of Table 310 16 Allowable Ampacities of Insulated Copper Conductors Not more than three conductors in raceway or cable or direct burial based on ambient temperature of 30 C 86 F Not more than three conductors in raceway or cable or direct burial based on ambient temperature of 30 C 86 F Temperature Rating of Conductor See Table Temperature Rating of Conductor See Table Size 310 13 in Code Size 310 13 in Code AWG 75 AWG 75 C MCM 167 F MCM 167 F TYPES TYPES RH RHW RUH RH RHW RUH 14 2 12 2 THW THWN THW THWN XHHW USE XHHW USE 18 12 15 16 10 25 14 15 8 40 12 20 6 50 10 30 4 6
3. drain valve may be opened to flush during the cleanout process Clean remaining gasket material from tank and element flanges Do not reuse original element gasket The element gasket is Part No 5109 9 Replace elements as follows e Put a new gasket on each element Install into tank opening e Uniformly tighten element bolts Torque to approximately 32 ft lbs 10 Connect element wiring as necessary 11 Follow FILLING instructions to restore boiler to service Check for water leaks around elements and proper operation when boiler is filled Replace insulation and cabinet panel CHECKLIST Before calling for service check the following points to see if the cause of trouble can be identified and corrected Reviewing this checklist may eliminate the need of a service call and quickly restore the boiler to service The illustration on page 5 identifies the location of most of the boiler components BE SURE TO TURN OFF THE ELECTRICITY WHEN CHECKING EQUIPMENT Not enough or no heat 1 Be certain the electrical disconnect switch serving the boiler is in the ON position The pilot switch es on the cabinet front should be on e In some installations the boiler electrical service may be limited by the power company or boiler controls If the boiler operates on a controlled circuit heat may be effected 2 Check the fuses The electrical disconnect switch usually contains fuses e The boiler has fuses located behin
4. numbers are found on the boiler s rating plate Model No ASME No Date Installed Dealer s Name Dealer s Address Phone No City and State Zip KEEP THIS WARRANTY AND MANUAL POSTED ADJACENT TO THE BOILER FOR FUTURE REFERENCE WHENEVER MAINTENANCE ADJUSTMENT OR SERVICE IS REQUIRED BE SURE YOUR DEALER HAS FILLED IN THIS WARRANTY 12
5. territories or possessions and Canada when operated free of the damaging effects of uncontrolled thermal expansion and or water hammer b Any accident to the boiler any misuse abuse including freezing or alteration of it any operation of it in a modified form will void this warranty 3 4 5 6 7 4 SERVICE AND REPAIR EXPENSE Under this limited warranty the warrantor will provide only repair or a replacement tank or part thereof The owner is responsible for all other costs Such costs may include but are not limited to a Labor charges for service removal repair or reinstallation of the tank or any component part b Shipping delivery handling and administrative charges for forwarding the new tank or replacement part from the nearest distributor and returning the claimed defective tank or part to such distributor C All cost necessary or incidental for any materials and or permits required for installation of the replacement tank or part 5 LIMITATION ON IMPLIED WARRANTIES Implied warranties including any warranty of merchantability imposed on the sale of this boiler under state law are limited to one 1 year duration for the tank or any of its parts Some states do not allow limitations on how long an implied warranty lasts so the above limitation may not apply to you CLAIM PROCEDURE Any claim under this warranty should be initiated with the dealer who sold the boiler or with any other dealer handling the
6. warrantor s products If this is not practicable the owner should contact U S Customers Canadian Customers A O Smith Corporation A O Smith Enterprises Ltd 5621 W 115th Street P O Box 310 768 Erie Street Alsip IL 60803 Stratford Ontario N5A 6T3 Telephone 800 323 2636 Telephone 519 271 5800 a The warrantor will only honor replacement with identical or similar tank or parts thereof which are manufactured or distributed by the warrantor b Dealer replacements are made subject to in warranty validation by warrantor DISCLAIMER NO OTHER EXPRESS WARRANTY HAS BEEN OR WILL BE MADE IN BEHALF OF THE WARRANTOR WITH RESPECT TO THE BOILER OR THE INSTALLATION OPERATION REPAIR OR REPLACEMENT OF THE TANK OR PARTS THE WARRANTOR SHALL NOT BE RESPONSIBLE FOR WATER DAMAGE LOSS OF USE OF THE UNIT INCONVENIENCE LOSS OR DAMAGE TO PERSONAL PROPERTY OR OTHER CONSEQUENTIAL DAMAGE THE WARRANTOR SHALL NOT BE LIABLE BY VIRTUE OF THIS WARRANTY OR OTHERWISE FOR DAMAGE TO ANY PERSONS OR PROPERTY WHETHER DIRECT OR INDIRECT AND WHETHER ARISING IN CONTRACT OR IN TORT a Some states do not allow the exclusion or limitation of the incidental or consequential damage so the above limitation or exclusion may not apply to you b This warranty gives you specific legal rights and you may also have other rights which vary from state to state Fill in the following for your own reference Keep it Registration is not a condition of warranty The model and ASME
7. 5 8 45 3 75 6 65 2 90 4 85 1 100 3 100 1 0 120 2 115 2 0 135 1 130 3 0 155 1 0 150 4 0 180 2 0 175 250 205 3 0 200 300 230 4 0 230 350 250 250 255 400 270 300 285 500 310 0 0 600 40 400 335 700 375 500 380 750 385 600 420 800 395 700 460 900 425 750 475 1000 445 800 490 1250 485 900 520 1500 520 1000 545 1750 545 1250 590 2000 560 1500 625 These capacities relate only to conductors 1750 650 described in Table 310 13 in Code 2000 665 For ambient temperatures over 30 C see Correction Factors Note 13 in Code Power Circuit The boiler is equipped with one of the power circuit configurations shown in the table Power circuit wiring is type THHN rated 600 volts 105 C sized as necessary ELECTRICAL CONFIGURATION TABLE Boiler Type Voltage Between Control Elements Nameplate of Boiler Terminal Circuit Quantity Element Service Lugs Voltage Per Operating 1 Phase Contractor Voltage 208 gt 4 4 120 Delta EJN E With 4 208 gt lt 208 gt 4 208 120 gt Neutral lt 2405 Lle 240 lt 240 4 240 et ks amp 4 480 4 480 480 et ks amp 480 4 480 480 _ gt Neutral lug not necessary and not furnished due to three wire wye connection This means only three wires no neutral brought to boiler due to method of element connection Elements ope
8. DURA POWER MODELS NW 37 670 COMMERCIAL ELECTRIC WATER BOILERS Installation Operation Service Maintenance Limited Warranty 666 45451 AANARAAAAAAARAAAAAAANANN I A CAUTION TEXT PRINTED OR OUTLINED IN RED CONTINS INFORMATION L STANDARD RELATIVE TO YOUR SAFETY PLEASE READ THOROUGHLY BEFORE INSTALLING AND USING THE APPLIANCE ZA Sho FLOOD WARNING WATER PRODUCTS IF THE BOILER SHOULD BECOME IMMERSED IN COMPANY WATER AT ANY TIME THE BOILER SHOULD BE EXAMINED BY A COMPETENT SERVICE PERSON A DIVISION OF SMITH CORPORATION BEFORE IT IS RETURNED TO SERVICE RENTON WASHINGTON www hotwater com PLACE THESE INSTRUCTIONS ADJACENT TO THE BOILER AND NOTIFY OWNER TO KEEP FOR FUTURE REFERENCE BE SURE THAT THE WARRANTY INFORMATION HAS BEEN FILLED IN ON COMPLETION OF INSTALLATION PRINTED IN U S A 0004G 0900 PART NO 60047 002 REV 2 DIMENSIONAL DATA UL MINIMUM CLEARANCE REQUIREMENTS 24 ALL SIDES 12 TOP RELIEF VALVE NOTE ALLOW 30 CLEARANCE FOR HINGED CONTROL COMPARTMENT DOORS FITTING ELEMENTS CAN BE CHANGED WITH 24 CLEARANCE COMBINATION TEMPERATURE FIELD WIRING AND PRESSURE COMPARTMENT ALIFTINGLUGS ELEMENTS INSTALLED GAUGE FROM THIS SIDE ONLY TYPICAL 2 CONTROL INLET COMPARTMENT BOILERS WITH SINGLE CONTROL PANEL CAN BE NS AN ADDITIONAL CONTROL PANEL IS REQUIRED ON FURNISHED WITH PANEL MOUNTED RIGHT OR SSY UNITS ABOVE 500 KW RATED 208 OR 240 VOLTS LEFT S
9. ENTON WASH AUTOMATIC WATER BOILER MODEL NO ASME NO AMP VOLTS udo feito NO ELEMENTS WATTS EA TOTAL WATTS Treats ESCE E USE ON A C CURRENT ONLY FOR SUPPLY CONNECTIONS USE WIRE SUITABLE FOR AT LEAST 75 C FOREWORD APPROVALS These designs comply with requirements of Underwriters Laboratories and bear the U L label on the cabinet All models are built to the standards of Section IV of the American Society of Mechanical Engineers Boiler and Pressure Code inspected and identified by this symbol The ASME plate is located on the tank above the cleanout opening When specified the National Board of Boiler and Pressure Vessel Inspectors listing will be furnished and identified by an NB number on the ASME plate FEATURES RELIEF LOW WATER CUTOFF GAUGE OPENINGS 1 6 f MANUAL a HIGH LIMIT i e i ASME PLATE t t i CLEANOUT ELEMENT PLATE oI i Lg TANK CLEANOUT INLET FRONT INSTALLATION CODE REQUIREMENTS In addition to these instructions the equipment shall be installed in accordance with those installation regulations in force in the local area where the installation is to be made These shall be carefully followed in all cases Authorities having jurisdiction should be consulted before installations are made In absence of local codes the installation must comply with the latest edition of the National Electrical Code NFPA 70 Copies of thi
10. IDE FACING INLET 480 VOLT UNITS WILL REQUIRE ONLY ONE PANEL SIZES AND DATA 45KW THRU 720KW EIE e le le o Drain NW 37 45K 1 1 1 1 1 1 1 1 1 1 1 1 3 i 3 4 2 4 3 4 3 4 3 4 3 4 3 4 3 4 3 4 3 4 3 5 4 5 4 5 4 5 4 5 4 5 5 5 5 All fittings under 4 will be threaded type All fittings 4 and larger will be flanged 3 fittings extend 4 beyond jacket Where overall height is a problem a larger diameter vessel with a reduced height may be furnished A Lifting lugs and channel skid base on 96 gallon and larger units LIFTING LUGS BUSS END FITTING m di SUPPLIED BY OTHERS UL MINIMUM CLEARANCE REQUIREMENTS 24 ALL SIDES 12 TOP E NOTE ALLOW 30 CLEARANCE FOR HINGED CONTROL COMPARTMENT DOORS ELEMENTS CAN BE CHANGED WITH 24 CLEARANCE s ADDITIONAL CABINET HEIGHT REQUIRED WHEN CABLE POWER C3 RELIEF VALVE FEEDS ARE UTILIZED WILL VARY ee ae hr ere 1 FITTING DEPENDING UPON SIZE AND a I NUMBER OF LEADS AMMETER OPTIONAL t 4 TYPICAL CONNECTION TO A BUS DUCT EL cli COMBINATION VOLTMETER TEMPERATURE OPT AND PRESSURE GAUGE STD a CONTROL COMPARTMENT INCET BOILER DRAIN SIZES AND DATA 780KW THRU 3300KW Prefix Gal Cap Std KWInput K 5 T Outlet Drain NW 220 780K 25 1 2 30 5 1 2 5 1 1 2 NW 25 1 2 30 25 1 2 25 1 2 25 1 2 25 1 2 25 1 2 c I9
11. If the tank bottom has an accumulation of sediment it should be cleaned Lime scale should be removed from the elements by dissolving the accumulation in UN LIME delimer UNeLIME is a non muriatic delimer available through your dealer or distributor Do not use muratic or hydrochloric acid base deliming solutions to remove lime scale from the elements Do not pour delimer into tank All models Turn off electrical disconnect switch Drain the boiler following DRAINING instructions Remove the cabinet panel which covers the heating elements Remove insulation as necessary to reach the element area Remove the bolts from each element and remove the elements from the opening Disconnect element wiring as necessary e Use a twisting pulling action to remove elements scaled beyond the size of the tank opening Brush loose scale from elements Silicates sulfates and aluminates must be removed by scraping or other mechanical means Lime scale dissolvents will not remove these types of scale which are occasionally encountered Lime scale removal e Place limed ends of heating elements into UNeLIME delimer and allow scale to dissolve Do not permit delimer or water to contact heating element electrical terminals Flush cleaned ends of elements with water when deliming or cleaning is completed Remove sediment and scale from the tank bottom through the tank cleanout The make up water valve and boiler
12. W WATER PROBE EXTERNAL INTERLOCK TERMINALS REMOVE JUMPER IF USED 3 NOTICE ANY AUXILIARY CONTROL EQUIPMENT INSTALLED ON OR CONNECTED TO THIS BOILER WITHOUT PRIOR WRITTEN AUTO RESET CLEARANCE FROM THE FACTORY WILL HIGH LIMIT VOID THE WARRANTY ON THIS UNIT 2 REQ D CONTACTOR SOLID STATE STEP MODULATING CONTROLLER DO NOT USE AS GROUND P2 ad OR APPLY POTENTIAL TO CONTROLLER THERMISTOR TERMINALS SOLID STATE THERMOSTAT 15KW HEATING ELEMENTS NOTE ELEMENTS OPERATE AT 277 VOLTS DUE TO WYE CONNECTION AT ELEMENTS SYSTEM CLEANING The hot water system should be internally cleaned and flushed to remove contaminants which may have accumulated during installation System cleaning provides chemical stability necessary for component life and system performance Failure to clean the system may cause 1 Poor heating due to formation of gas Residual pipe dope thread cutting oil solder flux dirt and other foreign materials breakdown to form gas This is indicated by a continuing need for purging even through the system is closed Pump seal leakage Acidic water low pH and contamination such as soil and sand result in premature or recurring pump seal failures Automatic air valve leakage Contaminants cause sticky sealing surfaces and result in leakage Relief valve operation Gas formation increases system pressure and relief valve spillage Water leaks at joints
13. and fittings Corrosion and eventual failure of connections occur when system pH is low Noisy operation Heat transfer surfaces can be fouled with dirty oily water This plus gas lead to noisy water circulation A WARNING Be sure to turn off power when working on or near the electrical system of the boiler Never touch electrical components with wet hands or when standing in water When replacing fuses always use the correct size for the circuit OPERATION GENERAL Never operate the heating elements without being certain the boiler is filled with water and a pressure relief valve is installed in the relief valve opening provided An electronic type low water cutoff is provided on all boilers as standard equipment The water probe is installed near the top of the tank to monitor the presence of water The control circuit is opened if the water level is below this point The pilot switch on the cabinet front permits the boiler to be turned on and off without having to operate the electrical disconnect switch Additional switches may be provided for manually operating contactor coils A WARNING Full power is present whenever the cabinet door is opened even with the pilot switch es turned off Never operate the boiler with cabinet doors open or panels removed FILLING Refer to SYSTEM CLEANING section for preparing the system prior to final filling and operation Hard Water in areas which have hard water it may be desirab
14. d the cabinet door see page 5 for location 11 If the water was excessively hot and is now cold the high temperature cutoff may have operated manual reset equipped models To reset turn off electricity and remove the back panel and push the reset button e Repeated operation of the high temperature cutoff should be investigated by your servicer The capacity of the boiler may have been exceeded by a large demand for heat Large demands require a recovery period to restore water temperature Sediment or lime scale may be affecting boiler operation Refer to MAINTENANCE for details Water is too hot 1 Refer to TEMPERATURE REGULATION Boiler makes sounds 1 Sediment or lime scale accumulation on the elements may cause sizzling and hissing noises when the boiler is operating e The sounds are normal however the tank bottom and elements should be cleaned Refer to MAINTENANCE for details 2 Some of the electrical components of the boiler make sounds which are normal Contactors will click or snap as the boiler starts and stops e Transformers and contactors often hum Water leakage is suspected 1 Check to see if the drain valve is tightly closed 2 If the outlet of the relief valve is leaking it may represent e Excessive water pressure or air in the system Faulty relief valve 3 Examine the flange area of the elements and tank cleanout for gasket leakage Tighten the bolts or if nece
15. h satisfies the hot water requirements of the system Additional instructional literature is provided with the boiler for adjusting this control Always close and lock the cabinet door after making a temperature adjustment Turn on electricity DRAINING The boiler must be drained if it is to be shut down and exposed to freezing temperatures Maintenance and service procedures may also require draining the boiler 1 Turn off the electrical disconnect switch 2 Close the make up water valve and system valves as necessary 3 Open a nearby outlet to vent the parts of the system being drained 4 Open the boiler drain valve 5 If the boiler is being drained for an extended shutdown it is suggested the drain valve be left open during this period Follow FILLING instructions to restore boiler to service MAINTENANCE Boiler maintenance includes periodic tank flushing and cleaning and removal of lime scale from the heating elements Circulating pumps should be oiled MAINTENANCE SCHEDULE Flushing Mony LN Removal UN LIME Lime Scale As Needed Delimer and Removal element Per pump makers instructions Circulating Pump s gaskets 10 Tank flushing and circulating pump lubrication should be performed in accordance with the above schedule Tank sediment removal and element lime scale removal must be performed when needed as determined by period inspections Following are the instructions for pe
16. le to fill the system with soft water and or provide water treatment as recommended by a consultant familiar with local conditions In this way harmful water scale build up on the heating elements is minimized 1 Close the boiler drain valve and system valves as necessary 2 Open a vent in the highest point of the system to allow the air to escape Fully open the make up water inlet valve Fill the boiler and piping 4 Close the vent as water starts to flow from the opening Place the make up water valve in the desired position The boiler is now ready for START UP and TEMPERATURE REGULATION if being placed in operation for the first time START UP The following checks should be made by the installer when the boiler is placed into operation for the first time 1 Check all factory and field made water and electrical connections for tightness Repair water leaks and tighten electrical connections as necessary Turn on the electrical disconnect switch and pilot switch es mounted on the boiler cabinet Observe the operation of the boiler during the first heating cycle Temperature control and contactor operation should be checked by allowing the boiler to come up to temperature and shutoff automatically TEMPERATURE REGULATION Always turn off the electricity at the electrical disconnect switch when making a temperature control adjustment It is suggested the temperature adjustment be turned to the lowest setting whic
17. lve is provided in the top of the boiler A drain line from the relief valve should terminate near a suitable drain Do not thread plug or cap the end of the drain line The pressure setting of the relief valve should not exceed the pressure capacity of any component in the system including the boiler HIGH TEMPERATURE DEVICES Automatic Device The boiler control circuit contains a high temperature cutoff switch This device shuts off the heating elements if excessive water temperatures are reached The high temperature cutoff has an adjustable range of 100 to 240 F and automatically resets on a drop of temperature Manual Device A manual reset high limit will be in the control circuit in addition to the automatic device previously described The control has an adjustable range of 110 to 290 F and must be manually reset after a drop of temperature Reset button is located under the right side panel of the boiler Disconnect the power before removing the panel to push the button INSTALLATION REQUIRED ABILITY INSTALLATION OR SERVICE OF THIS BOILER REQUIRES ABILITY EQUIVALENT TO THAT OF A LICENSED TRADESMAN IN THE FIELD INVOLVED PLUMBING AND ELECTRICAL WORK ARE REQUIRED GENERAL Do not test electrical system before boiler is filled with water follow START UP procedure in this manual The principal components of the boiler are identified in Figure 1 The model and rating plate see illustration on page 4 provides cer
18. nged control compartment doors Elements can be changed with 24 clearance 4 The boiler may be installed in a confined space if adequate ventilation is provided ELECTRICAL General Check the boiler model and rating plate information against the characteristics of the branch circuit electrical supply Do not connect the boiler to an improper source of electricity Voltage applied to the boiler should not vary more than 5 10 of the model and rating plate marking for satisfactory operation Do not energize the branch circuit for any reason before the boiler is filled with water Doing so may cause the heating elements to burn out Such damage is not covered under the terms of the warranty The branch circuit is connected to the block through an opening provided on top of the boiler The boiler should be connected to a separate grounded branch circuit with overcurrent protection and disconnect switch These are part of the electrical supply system not components of the boiler as such they are obtained locally The boiler should be grounded in accordance with national and local codes Branch Circuit The branch circuit wire size should be established through reference to the National Electrical Code or other locally approved source in conjunction with boiler amperage rating Branch circuit wiring which connects to the boiler terminal block should be temperature rated at 75 C For convenience portions of the wire size
19. rate at 277 volts Voltage from a conductor to ground electrical raceway and water pipes is not measured No ground lug furnished If required installer can provide locally TYPICAL WIRING DIAGRAMS The following wiring diagrams are included in this manual to show typical arrangements of electrical components in the control and power circuits by voltage and phase charactreristics They are to be used as a reference by the installer or servicer in performing their work A diagram of the boiler wiring is furnished with the boiler WIRING DIAGRAM 208V OR 240V THREE PHASE DELTA WITH STEP CONTROL EXTERNAL INTERLOCK TERMINALS 2 3 iB AD REMOVE JUMPER IF USED CONTROL PILOT NOTICE NEC AND TRANSFORMER SWITCH CUTOFF ANY AUXILIARY CONTROL EQUIPMENT LOCAL INSTALLED ON OR CONNECTED TO CODES THIS BOILER WITHOUT PRIOR WRITTEN AUTO RESET CLEARANCE FROM THE FACTORY WILL HIGH LIMIT VOID THE WARRANTY ON THIS UNIT CONTROL CIRCUIT 2 REQ D FUSES PROBE CONTACTOR COILS SOLID STATE STEP ELEMENT MODULATING CONTROLLER 2 DO NOT USE AS GROUND OR APPLY POTENTIAL TO THREE POLE CONTROLLER THERMISTOR SOLID STATE CONTACTORS TERMINALS THERMOSTAT 15KW HEATING ELEMENTS WIRING DIAGRAM 480V THREE PHASE WYE LINE 480V 120V CONTROL TRANSFORMER 12 3 PILOT switcH CUTOFF GND PER NEC AND LOCAL CODES CONTROL CIRCUIT FUSES ELEMENT LO
20. rforming recommended maintenance FLUSHING Turn off the electrical disconnect switch Open the boiler drain valve Allow water to flow to an open drain until it runs clean Do not come in contact with the water being drained as it may be very hot Close the drain valve when finished flushing Turn on the electrical disconnect switch SEDIMENT REMOVAL Water borne impurities consist of fine particles of soil and sand which settle out and form a layer of sediment on the bottom of the tank In time if not removed the level of sediment might reach the heating elements For convenience sediment removal and element lime scale removal should be performed at the same time as follows WATER AND LIME SCALE REMOVAL Water and lime scale accumulations on the heating elements is a normal condition common to all immersion type elements Factors which affect the amount of this formation are 1 Amount of make up water used As the volume of make up water heated increases more scale results Water temperature As the temperature of the water is increased more scale is deposited on the elements Characteristics of water supply Regardless of water treatment the elements should be examined regularly Water scale accumulations may cause noises to occur during operation It is recommended that a lower heating element be removed periodically for examination If it is scaled all of the elements should be removed and cleaned
21. rohibit sale of a model of equivalent size and construction A O Smith will provide a model which complies with the regulations of your area in which case the consumer will be charged the difference in price between the like replacement and the energy efficient model required The warranty on the repair or replacement of the part portion or tank will be limited to the unexpired term of the original warranty 2 ALL OTHER PARTS If within ONE year after initial installation of this boiler any part or portion shall prove upon examination by the warrantor to be defective in material or workmanship the warrantor will repair or replace such part or portion at its option CONDITIONS AND EXPECTATIONS This warranty shall apply only when the boiler is installed in accordance with local plumbing and building codes ordinances and regulations the printed instructions provided with it and good industry practices In addition a pressure relief valve approved by the American Society of Mechanical Engineers must have been installed This warranty shall apply only when the boiler is used a 1 at temperatures not exceeding the maximum setting of its control 2 at water pressure not exceeding the working pressure shown on the boiler when filled with water free to circulate at all times and with the tank free of damaging scale deposits in a noncorrosive and non contaminated atmosphere in its original installation location in the United States its
22. s document are available from the National Fire Protection Association 1 Batterymarch Park Quincy MA 02269 GROUNDING Grounding and electrical wiring connected to the boiler must conform to the latest edition of the National Electric Code NFPA 70 Figure 1 below is an illustration of a typical model NW Commercial Electric Hot Water Boiler with the features called out PRESSURE RELIEF VALVE RELIEF VALVE OPENING ELECTRICAL CUTOFF PROBE OUTLET BLOCK TERMINAL TEMPERATURE ADJUSTMENT MODULATING STEP CONTROL CONTROL CIRCUIT gom TRANSFORMER LOW WATER CUTOFF CONTROL SWITCH CIRCUIT FUSES yy POWER CIRCUIT FUSES LOU 4 CONTROL CIRCUIT FUSE it LALLA FIGURE 1 5 IMPORTANT IT IS RECOMMENDED THAT A QUALIFIED SERVICE TECHNICIAN PERFORM THE INITIAL FIRING OF THE BOILER AT THIS TIME THE USER SHOULD NOT HESITATE TO ASK THE TECHNICIAN ANY QUESTIONS WHICH THEY MAY HAVE IN REGARD TO THE OPERATION AND MAINTENANCE OF THE BOILER BEFORE FILLING THE SYSTEM FOR OPERATION the hot water system should be internally cleaned and flushed to remove any contaminants which may have accumulated during installation See section of this manual titled SYSTEM CLEANING RELIEF VALVE An ASME rated pressure relief valve is furnished with the boiler A fitting for the relief va
23. ssary follow the WATER AND LIME SCALE REMOVAL procedure to replace the gaskets SYSTEM WATER TEST System water test Review SYSTEM CLEANING section for a description of six problems which result from loss of system chemical stability Chemical stability is checked by 1 Draw off water from system Is it dirty discolored or odorous 2 Whatis the pH of the system water It should be neutral or slightly alkaline Does air purged from system vents burn If so the air is actually gas If any of the above conditions are present all waterways should be cleaned and the water adjusted to an alkaline condition If you cannot identify or correct the source of malfunction 1 Place the boiler electrical disconnect switch in the OFF position 2 Close the make up water inlet valve to the boiler 3 Contact your servicer NW 37 THRU NW 670 ELECTRIC HOT WATER BOILER LIMITED WARRANTY A O Smith Corporation the warrantor extends the following LIMITED WARRANTY to the owner of this boiler 1 THE TANK If the tank in this boiler shall prove upon examination by the warrantor to have leaked due to natural corrosion from water therein during the FIRST year after initial installation the warrantor will at its option repair it or provide a replacement tank less elements and controls of equivalent size and then current model Some government agencies are requiring energy efficient standards for boilers In the event regulations p
24. tables from the Code are reproduced here It is suggested the electrician size the branch circuit at 125 percent of the boiler rating and further increase wire size as necessary to compensate for voltage drop in long runs Branch circuit voltage drop should not exceed 3 at the boiler Calculating Amperage Overcurrent Protection The boiler is factory wired for connection to three wire single phase or three and four wire three phase branch circuits In addition a ground conductor may be required Adiagram of the wiring is furnished with the boiler for the electrician s use An amperage table is on page 4 of this manual The boiler model and rating plate provides full load amperage data The rating of the overcurrent protection should be computed on the basis of 125 percent of the total connected load amperage Where the standard ratings and settings do not correspond with this computation the next higher standard rating or setting should be selected Boiler Circuits The boiler s electrical components are pictured and identified on page 5 The model and rating plate illustration on page 4 identifies the electrical characteristics Basically there are two electrical circuits The control circuit where the temperature control directly or indirectly operates the contactor coils The power circuit which is operated by the control circuit carries the electrical load of the heating elements The following describes the circuits
25. tain useful information required at installation Both of these references should be used to identify the boiler and its components Water boilers are usually placed in series with the heating system on the outlet side of the circulating pump The boiler piping should include inlet and outlet water valves to permit maintenance and service work to be performed without disturbing the rest of the system Detailed system installation drawings are normally provided by the equipment purchaser or system designer LOCATING THE BOILER For the best installation the boiler should be located 1 On a level surface Shim the channel type skid base as necessary if leveling is required 2 Near a floor drain e The boiler should be located in an area where leakage of the tank or connections will not result in damage to the area adjacent to the boiler or to lower floors of the structure When such locations cannot be avoided a suitable drain pan should be installed under the boiler The pan should be at least two inches deep have a minimum length and width of at least two inches greater than the dimensions of the boiler and should be piped to an adequate drain The discharge opening of the relief valve should always be piped to an open drain 3 Suggested clearances from adjacent surfaces are found on a label attached to the control compartment door e UL minimum clearances 24 all sides 12 top Allow clearance for hi
Download Pdf Manuals
Related Search