Honeywell Q674A-G User's Manual
Contents
1. H2 ANTICIPATOR COOL _ 4 COMPRESSOR o RELAY A POWER SUPPLY PROVIDE DISCONNECT MEANS AND OVERLOAD M7232 PROTECTION AS REQUIRED T 60 1165 6 Fig 16 Typical Q674 terminal designations The thermostat and subbase used determines the number of system components controlled STAGE 1 HEATING RELAY STAGE 2 HEATING RELAY HEATING DAMPER Q674 SUBBASE COOLING DAMPER MOTOR OR CHANGEOVER VALVE STAGE 1 COOLING RELAY STAGE 2 COOLING RELAY MOTOR OR CHANGEOVER VALVE HEATING TRANSFORMER COOLING FAN RELAY COIL COOLING TRANSFORMER A A POWER SUPPLY PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED A ADD JUMPER RH RC FOR HOOKUP USING COMMON TRANSFORMER M3204A TEMPERATURE LEVER STOPS Some thermostats have factory installed temperature lever locking screws Fig 17 and or stop brackets Fig 18 Use these only if the HEAT and COOL tempera ture set point lever ranges are to be restricted If the compo nents are factory installed see the specific section below for the adjustment procedure If a temperature range restriction is required and the locking components are not factory installed it is neces sary to order a 4074ECK Envelope Assembly This enve lope includes two stop brackets one brass insert and one bracket mounting screw for restricting the adjustable ran2. HEATING Move the system switch on the subbase to AUTO or HEAT if used and the fan switch to AUTO Move the heating set point lever on the thermostat about 10 F 6 C above room temperature Heating should start and the fan should start after a short delay Fan starts immediately in heat pump systems Move the heat lever 10 F 6 C below room temperature The heating should shut off fan should shut off after a short delay Fan shuts off immediately in heat pump systems NOTE In heat pump applications time delays are involved before the compressor is activated to prevent short cy cling The delays are provided by a minimum off timer that prevents the compressor from starting for up to five minutes from when the thermostat last turned off the compressor or from when the system first received power COOLING Move the system switch on the subbase to AUTO or COOL if used and the fan switch to AUTO Move the cooling set point lever on the thermostat about 10 F 6 C below room temperature The cooling and fan should start see NOTE above Move the cool lever about 10 F 6 C above room temperature The cooling and fan should stop FAN Move the subbase system switch to OFF and the fan switch to ON The fan should run continuously Move the fan switch to AUTO In the AUTO position fan operation is controlled by the heating or cooling system control circuit Calibration THERMOSTAT T874 Thermostats are accurately calib
3. for heating and cooling Exact replacement for York model 2TB04700324 THERMOSTAT SUBBASE SYSTEM COMPONENTS HEAT RELAY 1 H1 ANTICIPATOR FAN SWITCH H2 ANTICIPATOR SYSTEM SWITCH Q OFFI 4 F 4_F 4_ FAN RELAY C1 ANTICIPATOR Q9 COMPRESSOR C2 ANTICIPATOR CONTACTOR 2 oat A POWER SUPPLY PROVIDE DISCONNECT MEANS AND OVERLOAD COMPRESSOR PROTECTION AS REQUIRED CONTACTOR 1 202 Fig 11 T874D E F Q674C in standard heating cooling system THERMOSTAT SUBBASE SYSTEM COMPONENTS L1 HOT Hi ANTICIPATOR VW H2 ANTICIPATOR SYSTEM SWITCH OFF H AUTO COMPRESSOR CONTACTOR 2 L2 C2 ANTICIPATOR COMPRESSOR CONTACTOR 1 L1 11 c2 A POWER SUPPLY PROVIDE DISCONNECT MEANS AND OVERLOAD HOT PROTECTION AS REQUIRED A JUMPER RH RC FOR SINGLE TRANSFORMER M3199B 5 60 1165 6 Fig 12 T874A D F Q674D in standard heating cooling system THERMOSTAT SUBBASE SYSTEM COMPONENTS HOT 12 HEAT RELAY 1 1 SWITCH HEAT RELAY 2 K FALL A COMPRESSOR NO CONTACTOR 2 SYSTEM 1 SWITCH 1 5 YS 1 COMPRESSOR CONTACTOR 1 L2 HOT POWER SUPPLY PROVIDE D
4. plate if used and subbase with the screws provided Do not fully tighten the subbase screws 4 Level the subbase using a spirit level as shown in Fig 3 and firmly tighten subbase mounting screws The subbase mounting holes provide for minor out of level adjustments IMPORTANT An incorrectly leveled subbase will cause the temperature control to deviate from setpoint Fig 3 Subbase components and leveling procedure WIRING TERMINAL THERMOSTAT CABLE OPENING 2 SPIRIT LEVEL MOUNTING POST FOR TO SPRING FINGER MOUNTING HOLES 4 CONTACTS ON THERMOSTAT 2 THE THERMOSTAT UP TO 12 M927 WIRING THE SUBBASE wiring must comply with local electrical codes and ordinances Follow equipment manufacturer wiring in structions when available To wire subbase proceed as follows 1 Connect the system wires to the subbase as shown in Figs 8 through 16 A letter code is located near each terminal for identification The terminal barrier permits straight or conventional wraparound wiring connections See Fig 4 Fig 4 Wiring connections FOR STRAIGHT INSERTION STRIP 5 16 IN 8 MM FOR WRAPAROUND STRIP 7 16 IN 11 MM BARRER SUBBASE TERMINAL SCREW M928 2 Your Q674 Subbase can require one or more jumpers that may or may not be factory supplied Refer to the wiring diagrams for specific terminals to be jumpered See Table 3 for proper application N CAUTION N
5. DUCT 1 Read these instructions carefully Failure to follow them could damage the product or cause a hazardous condi tion 2 Check the ratings given in the instructions and on the product to make sure the product is suitable for your application 3 Installer must be a trained experienced service tech nician 4 After installation is complete check out product operation as provided in these instructions CAUTION Disconnect power supply to prevent electrical shock or equipment damage 2 To prevent interference with the thermostat linkage keep wire length to a minimum and run wires close as possible to the subbase 3 Do not overtighten thermostat captive mount ing screws because damage to subbase threads can result 4 Do not short across coil terminals on heating relay or gas control This can burn out the thermostat heat anticipator IMPORTANT Thermostats are calibrated at the factory by using subbases mounted at true level Inaccurate subbase leveling will cause thermostat control de viation LOCATION Locate the subbase about 5 ft 1 5m above the floor in an area with good air circulation at average temperature Do not mount the subbase where the thermostat may be affected by drafts or dead spots behind doors and in corners hot or cold air from ducts radiant heat from sun appliances or fireplace concealed pipes and chimneys unheated uncooled areas such as an outsi
6. H L1 HOT Hi ANTICIPATOR AUTO ONU d 1 5 9 SYSTEM SWITCH HEAT Auro C r4 4 1 5 A FAN RELAY R ra 5 5 I NA C i0 C1 ANTICIPATOR COMPRESSOR 1 CONTACTOR 2 1 C2 ANTICIPATOR COMPRESSOR gt CONTACTOR 1 RISE e eg A POWER SUPPLY PROVIDE DISCONNECT MEANS AND OVERLOAD HOT PROTECTION AS REQUIRED A A JUMPER RH RC FOR SINGLE TRANSFORMER A OPTIONAL LED ON SOME MODELS Fig 9 T874C D Q674B in standard heating cooling system with separate transformers for heating and cooling THERMOSTAT SUBBASE SYSTEM COMPONENTS SWITCH FALL i H1 ANTICIPATOR 9 HEAT CHANGEOVER i VALVE t 0 e 1 FALL H2 ANTICIPATOR i SWITCH O COOL CHANGEOVER HEAT VALVE OFF 4 FAN RELAY T F X X COMPRESSOR C1 ANTICIPATOR CONTACTOR 2 1 2 COMPRESSOR 12 gt CONTACTOR 1 rey 69 L1 A POWER SUPPLY PROVIDE DISCONNECT MEANS AND OVERLOAD HOT PROTECTION AS REQUIRED A A JUMPER RH RC FOR SINGLE TRANSFORMER A OPTIONAL LED ON SOME MODELS 60 1165 6 4 Fig 10 T874D Q674B in standard heating cooling system with single transformer
7. Honeywell TRADELINE 874 Multistage Thermostats Q674A E G Subbases Installation Instructions for the Trained Service Technician Application The T874A F Thermostats provide 24 to 30 Vac control for heating and or cooling systems as listed in Table 1 TABLE 1 THERMOSTAT HEATING AND OR COOLING STAGES ma h s The Q674A E G Subbases provide wiring terminals system and fan switching and mounting bases for T874 Thermostats as listed in Table 2 TABLE2 SUBBASE SWITCHING POSITIONS _ 2 SUBBASE SWITCHING POSITIONS Q674 Switch Positions Model 5 nwe Operation On a 2 heat thermostat the two stages of heat make sequentially as the temperature drops Make refers to the mercury switch initiating a call for heat or cool There are about 2 F 1 C between stages so that the second stage makes only when the first stage cannot handle the load This is the interstage differential Recycling Notice This control contains mercury in a sealed tube Do not place control in the trash at the end of its useful life If this control is replacing a control that contains mer in a sealed tube do place your old control in the trash Contact your local waste management authority for instructions regarding recycling and the proper disposal of this control or of an old control containing mercury in a sealed tube Installation WHEN INSTALLING THIS PRO
8. ISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED A JUMPER RC RH FOR SINGLE TRANSFORMER B AND 5 TERMINALS AVAILABLE ON SOME MODELS M3667A Fig 13 T874D Q674E in standard heating cooling system THERMOSTAT H1 ANTICIPATOR FAN SWITCH Q H2 ANTICIPATOR SUBBASE SYSTEM COMPONENTS SYSTEM SWITCH nuc RISE OFF HEAT AUTO COOL C2 ANTICIPATOR j C1 ANTICIPATOR CHANGEOVER RELAY COOL COMPRESSOR CONTACTOR 2 60 1165 6 1 A POWER SUPPLY PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED A JUMPER RH RC FOR SINGLE TRANSFORMER 9 Tl L1 HOT COMPRESSOR 12 1 RC L1 HOT M3203B Fig 14 T874A F Q674G in standard heating cooling system THERMOSTAT SUBBASE SYSTEM COMPONENTS Hi L1 NO FAN HOT ANTICIPATOR SWITCH SYSTEM SWITCH COMPRESSOR CONTACTOR 2 C2 ANTICIPATOR 55 CONTACTOR 1 POWER SUPPLY PROVIDE DISCONNECT MEANS AND OVERLOAD HOT PROTECTION AS REQUIRED A A JUMPER RH RC FOR SINGLE TRANSFORMER M3201B Fig 15 T874C Q674B in standard application THERMOSTAT SUBBASE SYSTEM COMPONENTS H1 ANTICIPATOR L1 FAN SWITCH Hd exa ON _F 4_ 4 o FAN RELAY
9. de wall behind the thermostat MOUNTING THE SUBBASE The thermostat subbase can be mounted on a vertical outlet box horizontal outlet box or directly on the wall 1 If you must mount the subbase on a vertical outlet box order Honeywell 193121A Adapter Assembly Fig 1 The assembly includes an adapter ring two screws and a cover plate to cover marks on the wall Install the ring and cover plate on the vertical outlet box J H Rev 5 94 OHoneywell Inc 1994 Form Number 60 1165 6 Fig 1 Installation of subbase on outlet box COVER ADAPTER PLATE SCREWS 2 MOUNTING SCREWS 2 HORIZONTAL OUTLET BOX NOT INCLUDED WITH UNIT VAN ACCESSORY PARTS AVAILABLE 1931214 M925 For a wall installation hold subbase in position and mark holes for anchors See Fig 2 Obtain wall anchors locally Take care that the wires do not fall back into the wall opening Set aside subbase Drill two 3 16 in 4 8 mm holes and gently tap anchors into the holes until flush with the wall Fig 2 Installation of subbase on wall WIRES THROUGH WALL OPENING ANCHORS MOUNTING 2 HOLES LU MOUNTING M926 SUBBASE SCREWS 2 2 Pull electrical wires through the cover plate if used and subbase cable opening Fig 3 See Wiring the Subbase section before pulling any wires IMPORTANT Use 18 gauge color coded thermostat cable for proper wiring 60 1165 6 3 Secure the cover
10. ed paper containing at least 10 post consumer paper fibers www honeywell com yourhome
11. ever install more than one wire per terminal unless factory supplied jumper with spade termi nal is used See Fig 7 TABLE 3 JUMPER APPLICATIONS ed Fig 6 Jumper adjacent terminals for special If your subbase has Application system hookup Strip wire 3 4 in 19 mm RC RH terminals single transformer 5 system operation or LED nonadjacent indication terminals 3 Firmly tighten each terminal screw 4 Fit wires as close as possible to the subbase Push excess wire back into the hole 5 Plug hole with nonflammable insulation to prevent drafts from affecting the thermostat Fig 5 Jumper RC and RH for single trans former system Strip wire 3 4 in 19 mm Amo ADJACENT TERMINALS SHOWN JUMPERED ARE FOR EXAMPLE ONLY COMPARE WIRING DIAGRAM AND SUBBASE TO IDENTIFY TERMINALS TO BE JUMPERED M930 be bd be be bo be Fig 7 For nonadjacent terminals use jumper supplied with subbase JUMPER WIRE SUPPLIED WITH SOME MODELS NOTE Only the T874D Thermostat is shown with the subbases This thermostat subbase provides 2 stage heat ing and 2 stage cooling connections If using another model see Fig 16 and Table 4 TABLE 4 THERMOSTAT BULB CONFIGURATOIN Model No Heating Bulbs Cooling Bulbs me f oe mw mam 3 60 1165 6 Fig 8 T874A D Q674A in standard heating cooling system THERMOSTAT SUBBASE SYSTEM COMPONENTS FAN SWITC
12. ge of the HEAT and COOL set point levers Also the enve lope includes two screws with plastic insulated heads for locking the set point control levers in position If the components are to be used see the specific section below for the installation procedure Fig 17 Location of lever locking screws LEVER LOCKING SCREWS N 2 2 M18680 Fig 18 Location of lever stop brackets LEVER STOP BRACKETS M18681 60 1165 6 INSTALL AND ADJUST LOCKING LEVER SCREWS The two screws with insulated heads should be used only if the HEAT and COOL levers are to be locked in place at a specific temperature control point Do not use standard screws that provide metal to metal contact with the lever brackets To install 1 Refer to Fig 20 for screw hole locations 2 Install the two screws with insulated heads in the indicated holes Do not overtighten screws 3 Set the HEAT lever and the COOL lever at desired temperature control points 4 Firmly tighten both screws INSTALL AND ADJUST STOP BRACKETS Install the stop brackets only if there is a need to restrict the adjustable range of the heating and cooling temperature set point levers To install 1 Turn to the back of the T874 Thermostat Locate the hole for the brass insert in the plastic base below the LED window See Fig 19 2 Push the brass insert into the hole with your finger 3 Turn to the front of the T874 Thermostat 4 Place the two stop bracket
13. rated at the factory They do not have provision for field calibration THERMOMETER The thermometer in the thermostat has been accurately calibrated at the factory The thermometer should need ad justment only if it has been dropped or shifted due to mishan dling If the set point lever and the thermometer reading do not agree use the following procedure 1 Remove the thermostat cover by pulling up from the bottom of the cover until it clears the mounting slots 2 Set the thermostat cover on a table near an accurate thermometer 3 Allowten minutes for cover thermometer to sense area temperature compare the readings Be careful not to touch the thermometer or breathe on it 4 Ifthe readings are the same replace cover and put the system into operation 5 Ifthe readings are different insert a small screwdriver in the thermometer slot Fig 24 and turn it until the ther mometers have the same reading 6 Replace thermostat cover and put the system into operation NOTE Hand heat will offset the thermometer reading After making each adjustment wait ten minutes for the thermometer to stabilize before comparing Fig 24 Thermometer calibration 5070 60 1165 6 Honeywell Automation and Control Solutions Honeywell International Inc Honeywell Limited Honeywell Limit e 1985 Douglas Drive North 35 Dynamic Drive Golden Valley MN 55422 Scarborough Ontario MIV 4Z9 Printed in U S A on recycl
14. raw of each stage The current draw must be measured with the thermostat removed from the subbase and the power on to the heating system 1 Connectan ac ammeter of appropriate range between the heating terminals of the subbase Stage 1 between W1 and RH or R Stage 2 between W2 and RH or R 60 1165 6 2 Move the system switch to AUTO or HEAT if used 3 After one minute read the ammeter and record the reading Stage 1 amperes Stage 2 amperes NOTE If equipment cycles too fast set the indicator to a higher current rating not more than one half division at a time and recheck cycle rate Most conventional 2 stage heating equipment is designed to operate at three cycles per hour per stage and 1 stage heating equipment at six cycles per hour at 50 percent load condition When using the T874 Thermostat in heat pump systems set the heat anticipator at 140 percent of the actual primary control current draw to reduce the cycling rate Fig 22 Adjustable heat anticipator scales STAGE ONE ANTICIPATOR HEATING CONTROL STAGE TWO ANTICIPATOR HEATING CONTROL MOVE INDICATOR TO MATCH CURRENT RATING OF PRIMARY CONTROL m5069 Most heat pump systems should cycle 2 1 2 to 3 times per hour 4 Hangthe upper edge ofthe thermostat cover on top of the thermostat base and swing the cover downward until it engages with the cover clip TEMPERATURE SETTING Move the heating and cooling set point leve
15. rs Fig 23 to the desired comfort positions One lever controls all stages of heating and another lever controls all stages of cooling The minimum differential between heating and cooling set point is 3 F 1 7 C Fig 23 Location of external components HEATING SET POINT LEVER COOLING SET POINT LEVER 50 60 70 80 L FAN SWITCH SYSTEM SWITCH M3205 THERMOMETER WHEN PROVIDED 60 1165 6 10 SUBBASE SETTING The subbase switching positions control the system operation as described below Fig 23 SYSTEM SWITCH some subbases do not have all of the following functions OFF Both the heating and cooling systems are off If the fan switch is in AUTO position fan is also off AUTO Thermostat automatically changes between heating and cooling system operation depending on the indoor temperature HEAT Heating system is automatically controlled by the thermostat Cooling system is off COOL Cooling system is automatically controlled by the thermostat Heating system is off FAN SWITCH ON Fan operates continuously AUTO Fan operates with cooling equipment as con trolled by the thermostat or with the heating equip ment as controlled by the plenum switch To move the subbase switches to the desired control positions use thumb and index finger to slide lever Lever must stop over desired function indicator position for proper circuit operation Checkout
16. s in position with the tabs in the slot between the HEAT and COOL levers See Fig 20 5 Insert the mounting screw into the two slots in the stop brackets and attach to the brass insert Tighten the screw to pull the brass insert into the back of the thermostat 6 Loosen the mounting screw enough so the stop brack ets can slide for adjustment 7 Move the HEAT and COOL set point levers to the maximum temperature that is desired 8 Slide the stop brackets until one rests against the HEAT lever and the other against the COOL lever 9 Firmly tighten the mounting screw 10 If the HEAT and COOL levers are to be locked in place at a specific temperature use the two insulated head screws supplied instead of the two adjustable lever stop brackets N CAUTION Do not use standard screws that provide metal to metal contact with the stop brackets Short circuit and potential equipment damage may result Fig 19 Installing brass insert LED WINDOW BRASS INSERT INSERT HOLE BACK OF THERMOSTAT M955A Fig 20 Installing stop brackets HOLES FOR INSULATED LOCKING LEVER SCREWS COOL LEVER HOLE WITH BRASS INSERT BRACKET TABS ADJUSTABLE DA LEVER STOP SCREW BRACKETS M18682 MOUNTING THE THERMOSTAT 1 Remove the thermostat cover by pulling the bottom edge of the cover upward until it snaps free of the cover clip NOTE The cover is hinged at the top and must be removed b
17. y pulling up at the bottom 2 Carefully remove and discard the polystyrene packing insert that protects the mercury switches during shipment 3 Turn over the thermostat base and note the spring fingers that engage the subbase contacts Make sure the spring fingers are NOT bent flat preventing proper electri cal contact with the subbase 4 Set the adjustable heat anticipator indicators to the respective current setting for each stage See Setting the Heat Anticipator section 5 Note the two tabs on the top inside edge of the thermostat base The tabs fit into corresponding slots on top of the subbase Mount the thermostat on the subbase 6 Align the two captive mounting screws in the ther mostat base with the posts on the subbase See Fig 21 Tighten both screws Do not overtighten screws or damage to subbase posts can result Fig 21 Mounting thermostat on subbase THERMOSTAT MOUNTING SLOTS 2 THERMOSTAT MOUNTING POST 2 THERMOSTAT 7 CAPTIVE MOUNTING 9 6 SCREWS 2 Settings SETTING THE HEAT ANTICIPATOR Move the indicator to match the current rating of the primary contro See Fig 22 When using the T874 Thermo stat with two stages of heating set each heat anticipator to match its respective primary control current draw If you cannot find the current rating on the primary control or if further adjustment is necessary see NOTE and use the following procedure to determine the current d
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