Residential Gas Furnace Operation - HVAC.Amickracing

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Wiring SchematicTwo Stage Variable Speed (White-Rodgers 50A51 and 50A61 Series Integrated<strong>Furnace</strong> Controls)120 VOLT, 60 HZ., 1 PH.POWER SUPPLYPER LOCAL CODES1NHGND1LCWH/1BKGR2345675ECM TM 2 4BLOWER 3MOTOR 21BK/8WH/7GR/BKJUMPERYL/BKGNDDOORSWITCHOPTIONALGNDBK/2BK/3BK/1BK/7BK/4WH/1WH/450A51-505/-506INTEGRATED FURNACE CONTROLEACHUMLINECIRCXFMRLINE NXFMR NHOT 120VAC890qwertyuiopasfTNSYL/4120V24VFUSE LINK5FUSE LINK2 3 5GAS VALVEHI3B/C2LO1YL/2YL/3IGNITORBR/1TCO2 TCO-BWHGRWHYL/1IND.MTR.GNDTCO-C4PRESSURE SWITCH2ND STAGEPRESSURE SWITCH1ST STAGEFLAMESENSORWH/7BK/5BK/6RD/6WH/6WH/5BLRDBROR/1BL/1RD/1ORYLYL/5WHGNDGR12345951021874126113CIR NIGNIND HIIND LOIND NIGN NTRTHGNDPS2MVHMVCOMMVLGNDPS1HLIHLOFPNEUTRAL120VACW1 INW2 ING INR OUTG OUTN/CW2 OUTB OUTDIPSWITCHOFF1 23DIAGNOSTICLEDONDIP SWITCHgRP2ONOFFCFMFANECM TM FAN CONTROLBK O Y YLO G W1 W2 B12345678LVTBP1hjk16 WIREHARNESSW1 CFMP1G FANON/OFFP1W2 CFM P121513INTERFACE CONTROL BOARDPIN CONNECTIONSAT INTEGRATED CONTROL12345678GW2W1P2P2P2P2P2P2P2P2TERMINALBOARDW1 INW2 INGR OUTG OUTN.C.W2 CFM OUTB OUT81K3INTEGRATED FURNACE CONTROLTYPICAL CONNECTIONK2K1COMPUTERTRTHR B/C24 VAC INTO THERMOSTAT16 WIRE HARNESS1 LINE CHOKE NOT USED ON ALL MODELS.2 USED ON DOWNFLOW/HORIZONTAL AND UPFLOW/HORIZONTALMODELS. TCO-B IS REVERSE FLOW SWITCH.3 DIRECT VENT MODELS HAVE ONE MANUAL RESET FLAME ROLLOUT SWITCH INSTEAD OF TWO, SINGLE-USE FUSIBLE LINKS,OR AUTO-RESET BIMETAL SWITCHES MAY BE USED ON SOME MODELS.4 USE ON 90% FURNACE MODEL ONLY.5 MAY BE A FUSE LINK OR A BIMETAL SWITCH.19
Integrated Control Quick ReferenceService TipsTo the qualified service man, these controls arevery simple and easy to work on. A list of requiredservice tools needed to work on any solid stateignition control today are listed below:A reliable Volt/OHM Multimeter (preferably adigital with a microamp scale on it). The MicroampMeter is used to measure flame current.A U-Tube Water Manometer (or pressure gauge) totest inlet and out gas valve pressure.An Incline Manometer with a 0-2" water column scaleto test pressure switches and ductwork static pressure.1. When the thermostat fan switch is placed in the“ON” position, the fan will run at heating fan speed.Low heat fan on two stage 50A51 series controls.2. In order to obtain cooling air flow, the thermostat“Y” terminal must be connected to the “Y” terminalon the control. If the “Y” is not connected, lowheat speed will be activated during a cooling cycle.3. If a single stage heat thermostat is used with the50A51 two stage control, there will be a 10 minutedelay between first and second stage heat if W1 andW2 are jumpered.4. The control requires one microamp DC minimumflame current in order to maintain a call for heat.5. The control will add seconds to the igniterheat-up period on second and third trial for ignitionwith interpurge between trials. See Integrated<strong>Furnace</strong> Control label or Timing Chart for details.6. Once flame current has been established by thecontrol for 10 seconds, the retry counter in the controlis reset to zero.7. If flame current is interrupted, the control willbreak current flow to the gas valve and immediatelybegin a recycle for ignition without a purge cycle orincrease in igniter warm-up time. If flame current isinterrupted during 2nd stage operation, the recyclesequence is initiated and Hi fire or 2nd stage willresume immediately.8. If a lockout occurs, the control automatically resetsthe trial for ignition sequence every one or two hoursprovided a call for heat continues to exist. See TimingChart , Reset Time Column, for details.9. To reset control after lockout:a. Interrupt line voltage power to the control fora minimum of 1 second.b. Turn thermostat system switch off and back ontwice within 30 seconds.10. Voltage input range:Line 97-132 VAC 50/60HZ – Nominal 120 volts ACControl 20-30 VAC 50/60HZ – Nominal 24 volts AC11. 50A50 controls with date codes prior to 9348require an isolation relay in the “Y” circuitwhen used with Add On Heat Pump Plus One kits,to prevent cold air complaints during defrost.The control would not allow a cooling (Y) andheating (W) output at the same time so the controlwould de-energize the “W” circuit and there wouldbe no supplement heat during defrost cycles.12. The humidifier accessory lead is energizedwhenever there is a heating call and the fan isoperating. See IFC Timing Chart for details, page10.13. The electronic air cleaner accessory lead isenergized whenever there is a 24 volt signal on G or Yor during a heating call when the indoor fan isoperating.A detailed troubleshooting chart for each model ofthe integrated furnace control is included in thismanual to help the service technician work throughabnormal conditions with these controls.The troubleshooting section with fault charts for allWhite-Rodgers controls are located on pages 48through 62. See page 48 for procedures and chartreferences.20
Page 1 and 2: 40” Residential GasFurnace Operat
Page 3 and 4: Contents - continuedManifold Pressu
Page 5 and 6: Model Nomenclature✽ U C 0 4 0 C 9
Page 7 and 8: Component Identification - ✽UY/
Page 9 and 10: White-Rodgers Integrated Furnace Co
Page 11 and 12: White-Rodgers Integrated Furnace Co
Page 13 and 14: White-Rodgers 50A50/50A51 Fault Dia
Page 15 and 16: Single Stage 50A50 and 50A55 Sequen
Page 17 and 18: Two Stage 50A51 Sequence of Operati
Page 19: Two Stage Variable Speed Sequence o
Page 23 and 24: ECM TM 2 Variable Speed Furnace Mot
Page 25 and 26: Furnace Motor Control Board Schemat
Page 27 and 28: White-Rodgers Flame Current Tester/
Page 29 and 30: Furnace Pressure Switch SettingsClo
Page 31 and 32: Gas Valves - continuedReplacement P
Page 33 and 34: Direct Vent Manifold Pressure Check
Page 35 and 36: Single Stage Twinning KitBAYTWIN400
Page 37 and 38: Two Stage Twinning KitBAYTWIN300A -
Page 39 and 40: Single Wire Twinning - For Models w
Page 41 and 42: Identifying Radiant Sense Controls5
Page 43 and 44: White-Rodgers 50A52-100 Sequence of
Page 49 and 50: White-Rodgers 50A52-100/101/102 Seq
Page 51 and 52: White-Rodgers Troubleshooting Proce
Page 53 and 54: 50A50 Flow Chart 22CCooling CycleCh
Page 55 and 56: 50A50 Flow Chart 4Main burnerigniti
Page 57 and 58: 50A51 Flow Chart 1Inducer BlowerChe
Page 59 and 60: 50A51 Flow Chart 33AIs diagnosticLE
Page 61 and 62: 50A51 Flow Chart 5Heat thermostatco
Page 63 and 64: 50A52 Flow Chart 2Inducer Draft Mot
Page 65 and 66: 50A52 Flow Chart 4RadiantSensorChec
Page 67 and 68: Legend - System Wiring50A52 ModelTe
Page 69 and 70: Notes68

Residential Gas Furnace Operation - HVAC.Amickracing

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