50M56U-843 Universal Single Stage HSI Integrated urnace Control Kit INSTALLATION INSTRUCTIONS INSTALLER MUST READ PAGE 3 CONTAINS WIRING HARNESS AND BLOWER CONNECTION INSTRUCTIONS OR ALL APPLICATIONS AND IMPORTANT OEM REPLACEMENT INSTRUCTION OR: TRANE / AMERICAN STANDARD RHEEM / RUUD BRYANT / CARRIER / DAY & NIGHT / PAYNE AILURE TO READ AND OLLOW ALL INSTRUCTIONS CAREULLY BEORE INSTALLING OR OPERATING THIS CONTROL COULD CAUSE PERSONAL INJURY AND/OR PROPERTY DAMAGE. DESCRIPTION The 50M56U-843 kit is a Universal Single Stage HSI Integrated urnace Control that employs a microprocessor to continually monitor, analyze, and control the proper operation of the gas burner, inducer, and fan. The kit contains: 50M56-843 Ignition Control Module 21D64-2 Ignitor Kit Set of Interconnect Harnesses Installation should be done by a qualified heating and air conditioning contractor or licensed electrician. If in doubt about whether your wiring is millivolt, line, or low voltage, have it inspected by a qualified heating and air conditioning contractor or licensed electrician. Do not exceed the specification ratings. All wiring must conform to local and national electrical codes and ordinances. This control is a precision instrument, and should be handled carefully. Rough handling or distorting components could cause the control to malfunction. ollowing installation or replacement, follow manufacturer s recommended installation/service instructions to ensure proper operation.! CAUTION Do not short out terminals on gas valve or primary control. Short or incorrect wiring may damage the thermostat. CONTENTS Description... 1 Precautions... 1 Specifications... 2 Installation... 2 Mounting & Wiring Operation... 6 Troubleshooting... 8! 21D64-2 WARNING 50M56-843 PRECAUTIONS ailure to comply with the following warnings could result in personal injury or property damage. IRE HAZARD Do not exceed the specified voltage. Replace existing control with exact model and dash number. Protect the control from direct contact with water (dripping, spraying, rain, etc.). If the control has been in direct contact with water, replace the control. Label all wires before disconnection when servicing controls. Wiring errors can cause improper and dangerous operation. Route and secure wiring away from flame. SHOCK HAZARD Disconnect electric power before servicing. Ensure proper earth grounding of appliance. Ensure proper connection of line neutral and line hot wires. EXPLOSION HAZARD Shut off main gas to appliance until installation is complete. www.white-rodgers.com www.emersonclimate.com PART NO. 37-7042E Replaces 37-7042D 1414
SPECIICATIONS ELECTRICAL RATINGS [@ 77 (25 C)]: Input Voltage: 25 VAC 50/60 Hz Max. Input Current @ 25 VAC: 0.45 amp Relay Load Ratings: Valve Relay: 1.5 amp @ 25 VAC 50/60 Hz 0.6 pf Ignitor Relay: 6.0 amp @ 120 VAC 50/60 Hz (resistive) Inducer Relay: 2.2 LA 3.5 LRA @ 120 VAC Circulator Relay: 14.5 LA 25.0 LRA @ 120 VAC lame Current Requirements: Minimum current to insure flame detection: 1 µa DC* Maximum current for non-detection: 0.1 µa DC* Maximum allowable leakage resistance: 100 M ohms *Measured with a DC microammeter in the flame probe lead OPERATING TEMPERATURE RANGE: -40 to 176 (-40 to 80 C) HUMIDITY RANGE: MOUNTING: Surface mount multipoise Timing Specs: (@ 60 Hz) lame Establishing Time: lame ailure Response Time: maximum 0.8 sec 2.0 sec Gases Approved: Natural, Manufactured, Mixed, Liquified Petroleum, and LP Gas Air Mixtures are all approved for use. INSTALLATION! WARNING IRE HAZARD Do not exceed the specified voltage. Replace existing control with exact model and dash number. Protect the control from direct contact with water (dripping, spraying, rain, etc.). If the control has been in direct contact with water, replace the control. Label all wires before disconnection when servicing controls. Wiring errors can cause improper and dangerous operation. Route and secure wiring away from flame. SHOCK HAZARD Disconnect electric power before servicing. Ensure proper earth grounding of appliance. Ensure proper connection of line neutral and line hot wires. EXPLOSION HAZARD Shut off main gas to appliance until installation is complete.! CAUTION Do not short out terminals on gas valve or primary control. Short or incorrect wiring may damage the thermostat. TIMING SPECIICATIONS (All times are in seconds, unless noted otherwise MOUNTING AND WIRING 50M56U-843 Pre-Purge 30 Initial Ignitor Warm-Up (1st 64 attempts) All wiring should be installed by a qualified heating and air conditioning contractor or licensed electrician, according to local and national electrical codes and ordinances. The control must be secured to an area that will experience a minimum of vibration and remain below the maximum ambient temperature rating of 176. The control is approved for minimum ambient temperatures of -40. When mounting the control, any orientation is acceptable. Choose a location that will not damage, obstruct or place stress on the control s terminations, system wiring harness or system components. After finding a suitable location, drill four (4) 1/8 holes for mounting control. To ensure proper mounting hole locations, use the control as a template. When drilling the holes, take care so that the transformer, wiring harness or other system components are not damaged. our (4) #8 sheet metal screws are provided to complete the installation. Refer to the wiring diagram and wiring table when connecting the 50M56U-843 control to other components of the system. UL approved, 105 C rated 18 gauge, stranded, 2/64 thick insulation wire is recommended for all low voltage safety circuit connections. UL approved 105 C rated 16 gauge min., stranded, 4/64 thick insulation wire is recommended for all line voltage connections. After installation or replacement, follow appliance manufacturer s recommended installation or service instructions to ensure proper operation. 17 Maximum Ignitor Warm-Up 19 Ignition Activation Period 2 Trial for Ignition Period 4 Retries 2 Recycles 3 Valve Sequence Period 12 Interpurge 60 Post-Purge 25 Lockout Time 275 Heat Delay-To-an-On 30 Heat Delay-To-an-Off 100/150* Cool Delay-To-an-On 6 Cool Delay-To-an-Off 45 Auto Reset 60 minutes *These times will vary depending on option switch position. See OPERATION section for further information. 2
INSTALLATION INSTALLER MUST READ OR PROPER INSTALLATION Wiring harnesses and a Universal 21D64-2 ignitor are included in this package. Refer to the enclosed Cross Reference and Harness Application Chart (Part Number 37-7077) for harness selection and ignitor application information. Ignitor installation instructions are in the UNIVERSAL 21D64-2 Ignitor package included with this kit. IMPORTANT: or continuous fan speed operation, one of the unused parked motor taps must be connected to the low heat speed terminal. ailure to do this will result in the blower not energizing in the constant fan mode operation. Refer to figure 1. Installer must read Page (6) Operation and follow option switch setting for proper control operation. In certain applications it may be necessary to remove the control board from the cover to be mounted in the space allowed. Standoffs supplied in the package must be installed before the control board can be mounted. 4 Blower lead extensions are included in the kit if extra length is needed to complete installation. igure 1 Pin 11 (RO In) or continuous fan speed connect one of the unused parked terminals here IMPORTANT OEM REPLACEMENT INSTRUCTIONS TRANE and AMERICAN STANDARD or all TRANE and AMERICAN STANDARD furnaces only: Install jumper 0151-290600 (included in this package) into the back of the furnace 12 pin connector harness from pin 5 to pin 11 as shown in igure 2. Make sure jumper snaps into the connector securely. RHEEM / RUUD (1994 and earlier models) If the furnace control being replaced has 2 green lights and NO amber light (furnace date code 3294 or earlier) a lame Sensor Kit, RHEEM Part Number 62-24044-71 (not available from White-Rodgers) is required. Install the flame sensor and plug the flame sensor lead into pin 7 of the connector on the furnace as detailed in the Rheem lame Sensor Kit instructions. Plug the furnace connector into harness B (included in this package). Plug the other end of harness B into the new module. Attach the orange wire from harness B (3/16 female ) to S on the new module to complete the flame sense circuit. BRYANT / CARRIER / DAY & NIGHT / PAYNE This kit will not replace BRYANT / CARRIER / DAY & NIGHT / PAYNE HK42Z013 modules or CARRIER / BDP modules using an 11 pin (straight) connector. Refer to the enclosed Cross Reference and Harness Application Chart (Instruction sheet Part Number 37-7077) included with this kit for the list of modules it replaces. York (P3UR/PCLU) Install Jumper 0151-290600 (included in this package) into the back of the furnace 12 pin connector harness from pin 5 to pin 11 as shown in figure 2. Make sure jumper snaps into the connector securely. 290600 J Pin 5 (RO Out) Jumper 0151-290600 (for Trane and American Standard applications and York P3UR/PCLU only) igure 2. 12 Pin Connector (back view) on existing Wire Harness in urnace 3
WIRING DIAGRAM HOT (LINE) TYPICAL SYSTEM WIRING DIAGRAM 120 VAC NEUTRAL (LINE) 24 VAC CLASS II TRANSORMER TH 24 VAC TR 50M56 HUMIDIIER COOL LO HEAT HI HEAT LINE XMR EAC HUM PARK PARK IND-N IND IGN IGN-N [4-Pin Connector] INDUCER IGNITOR CIRCULATOR BLOWER ELECTRONIC AIR CLEANER CIR N LINE N XMR N HUM N EAC N Y Y W G W G COMPRESSOR CONTACTOR R R C THERMOSTAT 1 STAGE GAS VALVE or 2 STAGE GAS VALVE LAME SENSOR PROBE S HLO MV LO TH PSO RO OUT TR HLI GND MV COM PSI RO IN MV HI [12-Pin Connector] HIGH LIMIT (N. C.) ROLLOUT (N. C.) AUX. HIGH LIMIT (N. C.) PRESSURE SWITCH (N. O.) or Goodman 50M56-289 Application LEGEND 4 IND IGN IND N IGN N 4-Pin Connector HLO PSO HLI PSI MV LO TH RO OUT TR GND MV COM RO IN MV HI 12-Pin Connector Low Voltage (24 VAC) Line Voltage (120 VAC) N. C. = Normally closed switch N. O. = Normally open switch
WIRING DIAGRAM 50M56 TERMINAL W G R Y C HLO (Pin 1) MV LO (Pin 2) TH (Pin 3) PSO (Pin 4) RO OUT (Pin 5) TR (Pin 6) HLI (Pin 7) GND (Pin 8) MV COM (Pin 9) PSI (Pin 10) RO IN (Pin 11) MV HI (Pin 12) IND (Pin 1) IGN (Pin 2) IND-N (Pin 3) IGN-N (Pin 4) COOL LO HEAT HI HEAT PARK (2 terminals) LINE XMR EAC (optional) HUM (optional) CIR N LINE N XMR N EAC N (optional) HUM N (optional) S TERMINAL TYPE HLO PSO HLI PSI MV LO TH IND RO OUT TR IGN TYPICAL SYSTEM WIRING TABLE Terminal block with captive screws Maximum recommended flame probe wire length is 36 inches. GND MV COM IND N RO IN MV HI IGN N SYSTEM COMPONENT CONNECTION low voltage thermostat W terminal (or equivalent) low voltage thermostat G terminal (or equivalent) low voltage thermostat R terminal (or equivalent) low voltage thermostat Y terminal (or equivalent) (2nd wire from Y terminal goes to 24 VAC HOT side of compressor contactor coil) 24 VAC COMMON side of compressor contactor coil high limit OUTPUT gas valve first stage 24 VAC transformer (low voltage HIGH side) pressure switch OUTPUT rollout switch OUTPUT 24 VAC transformer (low voltage COMMON side) high limit INPUT MUST BE RELIABLY GROUNDED TO CHASSIS gas valve COMMON pressure switch INPUT rollout switch INPUT gas valve second stage inducer HOT side ignitor HOT side inducer NEUTRAL side ignitor NEUTRAL side circulator blower COOL SPEED terminal circulator blower LO HEAT SPEED terminal circulator blower HI HEAT SPEED terminal unused terminals input voltage (120 VAC) HOT side 24 VAC transformer line voltage HOT side electronic air cleaner HOT side humidifier HOT side circulator blower NEUTRAL terminal input voltage (120 VAC) NEUTRAL side 24 VAC transformer line voltage NEUTRAL side electronic air cleaner NEUTRAL side humidifier NEUTRAL side flame sensor probe 5
OPERATION OPTION SWITCHES The option switches on the 50M56U-843 control are used to determine the length of the heat delay-to-fan-off period, the mode of operation, and the 2nd stage delay period. The following illustration shows the options and the selections of the switch positions. The switches are shown in the factory default positions. HEAT MODE When heat is required, the thermostat will send a call for heat to the control. This starts the control s heating sequence. The ignitor and humidifier (optional) are powered. The ignitor is powered after the pre-purge period. Upon initial application of power, the ignitor warm-up time is 17 seconds. The ignitor on-time will then be increased depending on whether or not flame is achieved. The warm-up time is limited to a maximum of 19 seconds. During the first 64 warmup periods following power-up, the warm-up time may not be less than 17 seconds. In the event of a retry, the warm-up time will be increased by one second and locked in at that duration. Once the warm-up time is locked, it remains fixed until another call for heat results in a retry, in which case the warm-up time is again increased by one second and remains locked. In the event of two successive retry attempts, the warm-up time will be unlocked and set to 19 seconds. If flame is then achieved, the warm-up time will begin adapting again with the next call for heat. If, however, this third attempt fails to achieve flame, the control will go into system lockout. After the ignitor warm-up period, MV LO (first stage) and MV HI (second stage) are both energized to the gas valve. lame must be detected within 4 seconds. If flame is detected, the 30-second HEAT delay-to-fan-on period begins. The circulator and electronic air cleaner (optional) will also energize at this time. 1 Stage operation If the Option Switch MODE (SW1-2) is set to the 1 STG position, both MV LO and MV HI will remain energized. 2 Stage operation (Goodman 50M56-289 Application only) If the Option Switch MODE is set to 2 STG, MV HI will deenergize after 5 seconds, leaving MV LO energized. If the MODE is in the 2 STG position, 2nd STG DLY (SW1-3) will determine the second stage- on delay as follows: 5 MIN On call for heat, the 5 minute 2nd stage recognition timer begins. After the 5-minute delay, the second stage heat (MV HI) is energized. AUTO On call for heat, the automatic second stage will determine the optimum timing between stages for comfort. Auto will adapt the delay to energize MV HI from instantly to up to 12 minutes. When the thermostat is satisfied, the gas valve is de-energized. After proof of flame loss, the heat delay-to-fan-off period begins and the inducer blower remains energized to purge the system for 25 seconds. When the purge is complete, the inducer blower is de-energized. After the delay-to-fan-off period ends, the circulator fan and electronic air cleaner are de-energized. 6 * * *MODE and 2ND STG DLY for Goodman 50M56-289 only If flame is not detected, both valves are de-energized, the ignitor is turned off, and the 50M56U-843 control goes into the retry sequence. The retry sequence provides a 60-second wait following an unsuccessful ignition attempt (flame not detected). After this wait, the ignition sequence is restarted with an additional 1 second of ignitor warm-up time. If flame is established for more than 10 seconds after ignition, the 50M56U-843 controller will clear the ignition attempt (or retry) counter. If flame is lost after 10 seconds, it will re-cycle the ignition sequence. During burner operation, a momentary loss of power of 50 milliseconds or longer will de-energize the main gas valve. When power is restored, the gas valve will remain de-energized and a restart of the ignition sequence will begin immediately. A momentary loss of gas supply, flame blowout, or a shorted or open condition in the flame probe circuit will be sensed within 2.0 seconds. The gas valve will de-energize and the control will restart the ignition sequence. Recycles will begin and the burner will operate normally if the gas supply returns, or the fault condition is corrected. If the control has gone into system lockout, it may be possible to reset the control by a momentary power interruption of one second or longer. Refer to SYSTEM LOCKOUT EATURES. COOL MODE In a typical system, a call for cool is initiated by closing the thermostat contacts. This energizes the 50M56U-843 control and the compressor. The cool delay-to-fan-on period begins. After the delay period ends, the optional electronic air cleaner is energized, and the circulator fan is energized at cool speed. After the thermostat is satisfied, the compressor is deenergized and the cool mode delay-to-fan-off period begins. After the delay-to-fan-off period ends, the circulator fan and electronic air cleaner (optional) are de-energized. MANUAL AN ON MODE If the thermostat fan switch is moved to the ON position, the circulator fan (low heat speed) and optional electronic air cleaner are energized. When the fan switch is returned to the AUTO position, the circulator fan and electronic air cleaner (optional) are de-energized. SYSTEM LOCKOUT AND DIAGNOSTIC EATURES SYSTEM LOCKOUT EATURES When system lockout occurs, the gas valve is de-energized, the circulator blower is energized at heat speed, and, if flame is sensed, the inducer blower is energized. The diagnostic indicator light will flash or glow continuously to indicate system status. (System lockout will never override the precautionary features.) To reset the control after system lockout, do one of the following: 1. Interrupt the call for heat or cool at the thermostat for at least one second but less than 20 seconds (if flame is sensed with the gas valve de-energized, interrupting the call for heat at the thermostat will not reset the control). 2. Interrupt the 24 VAC power at the control for at least one second. You may also need to reset the flame rollout sensor switch. 3. After one hour in lockout, the control will automatically reset itself.
OPERATION DIAGNOSTIC EATURES The 50M56U-843 control continuously monitors its own operation and the operation of the system. If a failure occurs, the LED will indicate a failure code as shown on page 8. If the failure is internal to the control, the LED will stay off or flash 8 times. In this case, the entire control should be replaced, as the control is not field-repairable. ailure codes will flash the LED in the following flashpause sequences to indicate failure status (each flash will last approximately 0.25 seconds, and each pause will last approximately 2 seconds). AULT RECALL The last five fault codes stored can be displayed on the diagnostic LED. When the control is in standby mode (no call for heat or cool), press the AULT RECALL switch for approximately two seconds or until the diagnostic LED turns off. Release the switch and the LED will remain off for two seconds. Then the fault codes will display beginning with the most recent fault first with a two second pause between codes. After the stored fault codes have all displayed, the LED will remain off for two seconds and then turn on to indicate return to normal status. While displaying the stored fault codes, the control will ignore any new call for heat, cool or fan. AULT CODE RESET The stored fault codes can be erased from memory. When the control is in standby mode (no call for heat or cool), press the AULT RECALL switch for five to ten seconds or until the diagnostic LED begins to rapid flash. When the switch is released, the LED will turn off for two seconds to indicate the codes are erased. After two seconds the LED will turn on to indicate return to normal status. If the switch is held pressed for over ten seconds the rapid flash will stop and the LED will be on to indicate return to normal status. The 50M56U-843 has only one serviceable part an automotive type fuse, which protects the low voltage transformer from damage if the output is short-circuited. If the fuse has opened up, remove whatever caused the short circuit and replace the fuse with only a 3 Amp automotive type fuse. If the fuse does not correct the condition, replace the entire 50M56U-843 control. There are no other user serviceable parts. DEINITION O TERMS Auto Restart After one (1) hour of internal or external lockout, the control will automatically reset itself and go into an auto restart purge for 60 seconds. Cool Delay-To-an-Off The period of time between the loss of a call for cool and the deactivation of the blower motor at Cool speed. Cool Delay-To-an-On The period of time after a thermostat demand for cool before energizing the circulator blower motor at Cool speed. lame ailure Response Time (RT) The period of time between loss of the supervised main burner flame and the action to shut off the gas supply. Heat Delay-To-an-Off The period of time between the loss of a call for heat and the deactivation of the blower motor at Heat speed. Heat Delay-To-an-On The period of time between proof of the supervised main burner flame and the activation of the blower motor at Heat speed. Igniter Warm-up Time The length of time allowed for the igniter to heat up prior to the initiation of gas flow. Ignition Activation Period (IAP) The period of time between energizing the main gas valve and deactivation of the ignition means prior to the end of TI. Inter-purge The period of time intended to allow for the dissipation of any unburned gas or residual products of combustion between the failed trial for ignition and the retry period. Post-purge Time The period of time intended to allow for the dissipation of any unburned gas or residual products of combustion at the end of a furnace burner operating cycle. Post-purge begins at the loss of flame sense. Pre-purge Time The period of time intended to allow for the dissipation of any unburned gas or residual products of combustion at the beginning of a furnace operating cycle prior to initiating ignition. Recycles The additional attempts within the same thermostat cycle for ignition after loss of the supervised ignition source or the supervised main burner flame. Retries The additional attempts within the same thermostat cycle for ignition when the supervised main burner flame is not proven within the first trial for ignition period. Trial for Ignition Period (TI) The period of time between initiation of gas flow and the action to shut off the gas flow in the event of failure to establish proof of the supervised ignition source or the supervised main burner flame. 7
Red LED lash Error/Condition Comments/Troubleshooting TROUBLESHOOTING 1 External lockout (exceeded retries) ailure to sense flame is often caused by carbon deposits on the flame sensor, a disconnected or shorted flame sensor lead or a poorly grounded furnace. Carbon deposits can be cleaned with emery cloth. Verify sensor is not contacting the burner and is located in a good position to sense flame. Check sensor lead for shorting and verify furnace is grounded properly. Verify gas supply to valve, gas valve in "On" position and appliance lighting properly. Verify flame reaches flame sensor during ignition attempts and gas pressures are correct. 2 Pressure switch stuck closed Pressure switch stuck closed. Check switch function, verify inducer is turning off. Refer to wiring diagram, terminals PSI / PSO. 3 Pressure switch stuck open Check pressure switch function and tubing. Verify inducer is turning on and pulling sufficient vacuum to engage switch. Refer to wiring diagram, terminals PSI / PSO. 4 Open high temperature limit switch Verify continuity through limit switch circuit. Refer to wiring diagram terminals, HLI / HLO. 5 lame sensed with gas valve de-energized Verify the gas valve is operating and shutting down properly. lame in burner assembly should extinguish promptly at the end of the cycle. Check orifices and gas pressure. 6 Open rollout switch or open fuse Verify continuity through rollout switch circuit. Refer to wiring diagram terminals, RO IN / RO OUT. Verify continuity of fuse which protects the low voltage transformer from damage if the output is short-circuited. If the fuse has opened up, remove whatever caused the short circuit and replace the fuse with only a 3 Amp automotive type fuse. If the fuse does not correct the condition, replace the entire control. 7 Low flame sense current Low flame sense current is often caused by carbon deposits on the flame sensor, a poorly grounded furnace or a mis-aligned flame sense probe. Carbon deposits can be cleaned with emery cloth. Check or improve furnace and module ground. Verify sensor is located in or very near flame as specified by the appliance manufacturer. Refer to wiring diagram S terminal and GND. 8 Ignitor relay fault This flash code does not indicate a broken, disconnected or shorted ignitor. It indicates the ignitor relay contacts on the ignition module are not functioning properly. Replace the ignition module. Rapid lash Reversed polarity Verify the control and furnace are properly grounded. Check and reverse polarity (primary or secondary) if incorrect. Continuous On Normal operation No fault Off Control failure Verify power to the control, replace control if power is at the control and no lit Red LED TECHNICAL SUPPORT: 1-888-725-9797 White-Rodgers is a business of Emerson Electric Co. The Emerson logo is a trademark and service mark of Emerson Electric Co. www.white-rodgers.com www.emersonclimate.com
50M56U-843 Harness Application Chart Module Model Number Número de Modelo del Módulo Numéro de Modèle du Module 50M56U-843 Cross Reference and Harness Application Data Correspondances et données d applications du harnais 50M56U-843 50M56U-843 Referencia cruzada e información sobre la aplicación del arnés urnace Model Modelo de Calefactor Modèle de ournaise Harness Arnés Harnais Ignitor Quemador Allumeur urnace OEM OEM del Horno OEM de our Coleman/Evcon/Luxaire/York 031-00662 031-00662-000 031-00662-700 N/A *P2URD or PBLU N/A Use existing or / Usar Coleman/Evcon/Luxaire/York Coleman/Evcon/Luxaire/York 031-01250-000 N/A Coleman/Evcon/Luxaire/York 031-01250-700 N/A Coleman/Evcon/Luxaire/York 031-01266-000 *6MG, L8, G9T, GUD, P1CK, Coleman/Evcon/Luxaire/York P1CX, P2DR, P3DH, P3DN, P3HU, P3UR, PACE, PACR, PBLD, PCD, PCLU, PCUH 031-01266-700 N/A Coleman/Evcon/Luxaire/York 031-01284-000 N/A Coleman/Evcon/Luxaire/York 031-09166-000 N/A Coleman/Evcon/Luxaire/York 031-09167-000 N/A Coleman/Evcon/Luxaire/York 100925-02 N/A 21D64-2 Lennox 100925-03 N/A Lennox 1010806 N/A E & Use existing or/ Usar Heil Quaker/ICP/ Thermo Products/Whirlpool 1012-83-9336AHSC1 N/A A & C 21D64-2 United Technologies 1012-83-9337A N/A A & C United Technologies 1012-925A N/A B & D United Technologies 1012-925B N/A B & D United Technologies 1012-925C N/A B & D United Technologies 1012933D N/A A & C United Technologies 1012-933D N/A A & C United Technologies 10207701 N/A Use existing or / Usar Amana/Goodman 102077-02 N/A E & Amana/Goodman 102077-03 N/A E & Amana/Goodman 10207704 N/A E & Amana/Goodman 102077-04 N/A E & Amana/Goodman 10207706 N/A E & Amana/Goodman 102077-09 N/A E & Amana/Goodman 10207710 N/A E & Amana/Goodman 10207714 N/A E & Amana/Goodman 10207717 N/A 21D64-2 Amana/Goodman 10207718 N/A E & Use existing or / Usar Amana/Goodman 10207719 N/A E & Amana/Goodman 10207720 N/A 21D64-2 Amana/Goodman 10207720S N/A Amana/Goodman 10M93 N/A Lennox 10M9301 N/A Lennox 12L6901 N/A Lennox 1214201 N/A Use existing or / Usar Lennox 1380686 N/A International Comfort Products 1380698 N/A International Comfort Products 1380699 N/A International Comfort Products www.white-rodgers.com www.emersonclimate.com PART NO. 37-7077C Replaces/Sp/r 37-7077B 1104
Module Model Number Número de Modelo del Módulo Numéro de Modèle du Module 2 urnace Model Modelo de Calefactor Modèle de ournaise 265901 *DGAD, DGAE, DGA, G8, G9S, GG8S, GG9S, GGLS, GM8S, GM9, GM9S, GR8S, GY8S, GY9, GY9S, G8C, L8S, LM8S, LY8S, MG9S, TG8S, TG9S, TGLS, UGAA, UGAB, UGAD, UGAE, UGA 265902 *L8S, C8S, L9S, C9S, GY8S, LC8S, LL8S, PS8A, PS8B, PS8C, PS8D, PS8E, PS9A, PS9B, PS9C, PS9D Harness Arnés Harnais Ignitor Quemador Allumeur Use existing or / Usar urnace OEM OEM del Horno OEM de our Coleman/Evcon/Luxaire/York Coleman/Evcon/Luxaire/York 03101250000 *P3MPD, P2DPD, P2MPV, PBKD Coleman/Evcon/Luxaire/York 031-01973-000 N/A Coleman/Evcon/Luxaire/York 32M8801 N/A 21D64-2 Lennox 331-01933-000 N/A Use existing or / Usar Coleman/Evcon/Luxaire/York 331-01972-000 N/A Coleman/Evcon/Luxaire/York 331-09167-000 N/A Coleman/Evcon/Luxaire/York 350486 N/A Thermo Products 350836 N/A 21D64-2 Thermo Products 41-5 N/A A & C Texas Instruments 50A50-110 N/A Use existing or / Usar Heil Quaker/ICP 50A50-111 N/A Synder General 50A50-112 N/A Heil Quaker/ICP 50A50-113 N/A American Standard/Trane 50A50-130 N/A Heil Quaker/ICP 50A50-131 N/A Heil Quaker/ICP 50A50-142 N/A Heil Quaker/ICP 50A50-143 N/A American Standard/Trane 50A50-205 N/A Amana/Goodman 50A50-206 N/A Amana/Goodman 50A50-207 N/A E & Amana/Goodman 50A50-208 N/A Coleman/Evcon/Luxaire/York 50A50-209 N/A Coleman/Evcon/Luxaire/York 50A50-210 N/A Armstrong/Heil Quaker 50A50-215 N/A Clare Brothers-Canada 50A50-216 N/A DMO Industries 50A50-229 N/A Coleman/Evcon/Luxaire/York 50A50-230 N/A Coleman/Evcon/Luxaire/York 50A50-240 N/A Coleman/Evcon/Luxaire/York 50A50-241 N/A Coleman/Evcon/Luxaire/York 50A50-245 N/A White-Rodgers Standard 50A50-285 N/A E & White-Rodgers Standard 50A50-286 N/A White-Rodgers Standard 50A50-288 N/A E & Amana/Goodman 50A50-295 N/A American Standard/Trane 50A50-296 N/A American Standard/Trane 50A50-298 N/A E & Amana/Goodman 50A50-405 N/A American Standard/Trane 50A50-406 N/A American Standard/Trane 50A50-407 N/A White-Rodgers Standard 50A50-408 N/A American Standard/Trane 50A50-438 N/A White-Rodgers Standard 50A50-471 N/A American Standard/Trane 50A50-472 N/A American Standard/Trane 50A50-473 N/A American Standard/Trane 50A50-474 N/A American Standard/Trane 50A50-475 N/A Canadian Market 50A50-571 N/A American Standard/Trane 50A55-143 N/A Thermo Products/Heil Quaker/ ICP/Whirlpool 50A55-241 N/A Coleman/Evcon/Luxaire/York 50A55-245 N/A Canadian Market 50A55-250 N/A edders 50A55-285 N/A White-Rodgers Standard 50A55-286 N/A White-Rodgers Standard 50A55-288 N/A Amana/Goodman 50A55-289 N/A Amana/Goodman 50A55-438 N/A Heil Quaker/ICP/Whirlpool/ White-Rodgers Standard
Module Model Number Número de Modelo del Módulo Numéro de Modèle du Module urnace Model Modelo de Calefactor Modèle de ournaise Harness Arnés Harnais Ignitor Quemador Allumeur urnace OEM OEM del Horno OEM de our American Standard/Trane 50A55-474 50A55-476 50A55-480 XE80, XB90 American Standard XE80, XB90 American Standard N/A Use existing or / Usar American Standard/Trane American Standard/Trane 50A55-486 N/A American Standard/Trane 50A55-571 N/A American Standard/Trane 50A55-843 N/A Lennox/White-Rodgers Standard 50A56-242 *DGAD, DGAE, DGA, G8, G9S, Coleman/Evcon/Luxaire/York GG8S, GG9S, GGLS, GM8S, GM9, GM9S, GR8S, GY8S, GY9, GY9S, G8C, L8S, LM8S, LY8S, MG9S, MG9S, TG8S, TG9S, TGLS, UGAA, UGAB, UGAD, UGAE, UGA 50A56-243 *L8S, C8S, L9S, C9S, GY8S, Coleman/Evcon/Luxaire/York LC8S, LL8S, PS8A, PS8B, PS8C, PS8D, PS8E, PS9A, PS9B, PS9C, PS9D 50A65-120 N/A 21D64-2 Lennox 50A65-121 N/A Lennox 50A65-143 N/A Thermo Products 50A65-288 N/A Amana/Goodman 50A65-289 N/A Amana/Goodman 50A65-474 N/A American Standard/Trane 50A65-475 XR80, XR90, reedom 80 Single Stage American Standard/Trane 50A65-476 XR80, reedom 80 Single Stage American Standard/Trane 50A65-843 N/A White-Rodgers Standard 50A66-123 N/A Lennox 50M56-289 GDH, GME8, GMH E Use existing or / Usar Amana/Goodman 50M56-843 50M56U-843 Replacement Kit / Trousse de remplacement 50M56U-843 / Kit de reemplazo 50M56U-843 50T35-730 GSU, GSM A, C & G Use existing or / Usar Amana/Goodman 50T35-743 N/A A, C & G American Standard/Trane/ White-Rodgers Standard 50T55-288 GDS8, GHS8, GMS8 E & Amana/Goodman 50T55-289 GDS8, GHS8, GMS8 E & Amana/Goodman 52537074000 N/A Coleman/Evcon/Luxaire/York 52537077000 N/A Coleman/Evcon/Luxaire/York 56L84 N/A 21D64-2 Lennox 56L8401 N/A Lennox 613 N/A Texas Instruments 62-22694-xx *R/U GRA B & D Use existing or / Usar 62-22732-xx *R/U GSA B & D 62-24044-xx *R/U GTA B & D Rheem/RUUD** 62-24045-01 R/U GZC B & D 62-24046-01 R/U GDG B & D 62-24084-82 R/U GLH B & D 62-24268-01 R/U GDJ B & D 62-24268-02 R/U GLI B & D 62-24268-03 UGPJ B & D 624557 G6 B, H & I Nordyne 6245570 N/A B, H & I 21D64-2 Nordyne 624564 N/A B, H & I Nordyne 6245640 G4 B, H & I Use existing or / Usar Nordyne 624591 N/A B, H & I 21D64-2 Nordyne 624591-x *G5RA120-C B, H & I Use existing or / Usar Nordyne 624628 N/A B, H & I 21D64-2 Nordyne 624628-0 N/A B, H & I Nordyne 6246310 N/A B, H & I Nordyne 624631-0 N/A B, H & I Nordyne 624631A G3, G4, G5, G6, M2, M3 B, H & I Use existing or / Usar Nordyne 695-200 N/A B & D Rheem 3
Module Model Number Número de Modelo del Módulo Numéro de Modèle du Module urnace Model Modelo de Calefactor Modèle de ournaise Harness Arnés Harnais Ignitor Quemador Allumeur urnace OEM OEM del Horno OEM de our 69M0801 N/A 21D64-2 Lennox 6DT-1 N/A Texas Instruments 6DT-2 N/A Texas Instruments 710128A N/A B, H & I Nordyne 8068142 N/A Use existing or / Usar Whirlpool 8068561 N/A Whirlpool 8068563 N/A Whirlpool 902378 KG6RC B, H & I Nordyne 902696 N/A B, H & I 21D64-2 Nordyne 903106 G3, G4, G5, G6, M2, M3 B, H & I Use existing or / Usar Nordyne 99958174 N/A Whirlpool 99958175 N/A Whirlpool B1809926S N/A E & Amana/Goodman D330927P01 N/A Trane D330930P01 N/A Trane D330934P01 N/A Trane D340035P01 N/A Trane D340774P01 N/A Trane D341213P01 N/A 21D64-2 Trane D341396P01 N/A Trane G951ADB1401 N/A Coleman/Evcon/Lennox/Luxaire/York G951ADB1401C N/A Coleman/Evcon/Lennox/Luxaire/York G951ADB-1401C N/A Coleman/Evcon/Lennox/Luxaire/York G951ADB1402 N/A Coleman/Evcon/Lennox/Luxaire/York G951ADB-1402 N/A Coleman/Evcon/Lennox/Luxaire/York G951ADB-1403 N/A Coleman/Evcon/Lennox/Luxaire/York G951AEB-1403 N/A Use existing or / Usar Coleman/Evcon/Lennox/Luxaire/York HK42Z004, HK42Z007, HK42Z008, HK42Z009, HK42Z011 or HK42Z016 340MAV, 345MAV, 350MAV, 351DAS, 373LAV, 376CAV, 383KAV, 393AAV, 395CAV, 480BAV, 481BAV, 490AAV, 58MCA, 58MSA, 58MXA, 58PAV, 58RAV, 58WAV, 58YAV, 58ZAV, GB1AAV, GB3AAV, PG8DAA, PG8UAA, PG9MAA K & L 21D64-2 Bryant/Carrier/Day & Night/Payne ICM280 N/A A & C ICM P031-01267-001 N/A Use existing or / Usar Coleman/Evcon/Luxaire/York X4459 N/A Lennox X445901 N/A Lennox ootnotes: OEM furnace models abbreviated to shorten the length. Reference the control board P/N for proper replacement. Numéros de modèles de chaufferettes d origine abrégés pour des raisons d espace. ournir le numéro de pièce du tableau de commande pour obtenir un remplacement adéquat. *Nordyne/Rheem/York = additional numbers or letters *Les modèles Nordyne / Rheem comportent des chiffres ou des lettres supplémentaires *Los modelos Nordyne / Rheem tienen más números o letras N/A = Not Available N/D = Non disponible N/A = No Disponible **If existing furnace circuit board has 2 green lights and NO amber light (furnace date code 3294 or earlier), an additional lame Sensor Kit (Rheem Part 62-24044-71) may be required. **Si la carte de circuits imprimés existante de la fournaise est pourvue de deux voyants verts et d AUCUN voyant ambré (code de date de fournaise 3294 ou plus ancien), une trousse de détecteur de flamme (pièce no 62-24044-71 de RHEEM) peut être requise. **Si la placa de circuito del calefactor actual tiene 2 luces verdes y NINGUNA luz ámbar (código de fecha de calefactor 3294 o anterior), es posible que se necesite un kit detector de llama adicional (Rheem número de pieza 62-24044-71). 50M56U-843 will not replace HK42Z013 or control boards with an 11-pin bar connector. Le module 50M56U-843 ne remplace pas le module HK42Z013 ni les cartes de circuits imprimés à connecteur à 11 broches. 50M56U-843 no reemplaza HK42Z013 ni las placas de control con un conector de barra de 11pins. White-Rodgers is a division of Emerson Electric Co. The Emerson logo is a trademark and service mark of Emerson Electric Co. www.white-rodgers.com www.emersonclimate.com
INTEGRATED URNACE CONTROLS 50M56U-843 WIRING AND CONIGURATION HOT (LINE) 50M56U-843 TYPICAL WIRING DIAGRAM 120 VAC NEUTRAL (LINE) 24 VAC CLASS II TRANSORMER TH 24 VAC TR 50M56 HUMIDIIER COOL LO HEAT HI HEAT LINE XMR EAC HUM PARK PARK IND-N IND IGN IGN-N INDUCER IGNITOR CIRCULATOR BLOWER ELECTRONIC AIR CLEANER CIR N LINE N XMR N HUM N EAC N Y Y W G W G COMPRESSOR CONTACTOR R R C THERMOSTAT 1 STAGE GAS VALVE LAME SENSOR PROBE S PSI PSO HLI HLO R/O OUT GND R/O IN MV LO MV HI MV COM TR TH HIGH LIMIT (N. C.) ROLLOUT (N. C.) PRESSURE SWITCH (N. O.) AUX. HIGH LIMIT (N. C.) 2 STAGE GAS VALVE TECHNICAL HELP LEGEND Low Voltage (24 VAC) Line Voltage (120 VAC) N. C. = Normally closed switch N. O. = Normally open switch or Goodman 50M56-289 Application www.white-rodgers.com 209
50M56U-843 WIRING AND CONIGURATION INTEGRATED URNACE CONTROLS 50M56U-843 TYPICAL WIRING DIAGRAM W G R Y 50M56 TERMINAL C HLO (1) MV LO (2) TH (3) PSO (4) R/O OUT (5) TR (6) HLI (7) GND (8) MV COM (9) PSI (10) R/O IN (11) MV HI (12) IND (1) IGN (2) IND-N (3) IGN-N (4) TERMINAL TYPE Terminal block with captive screws 12-pin connector & harness 4-pin connector & harness SYSTEM COMPONENT CONNECTION low voltage thermostat W terminal (or equivalent) low voltage thermostat G terminal (or equivalent) low voltage thermostat R terminal (or equivalent) low voltage thermostat Y terminal (or equivalent) (2nd wire from Y terminal goes to 24 VAC HOT side of compressor contactor coil) 24 VAC COMMON side of compressor contactor coil high limit OUTPUT gas valve first stage 24 VAC transformer (low voltage HIGH side) pressure switch OUTPUT rollout switch OUTPUT 24 VAC transformer (low voltage COMMON side) high limit INPUT MUST BE RELIABLY GROUNDED TO CHASSIS gas valve COMMON pressure switch INPUT rollout switch INPUT gas valve second stage inducer HOT side ignitor HOT side inducer NEUTRAL side ignitor NEUTRAL side TECHNICAL HELP COOL circulator blower COOL SPEED terminal LO HEAT circulator blower LO HEAT SPEED terminal HI HEAT circulator blower HI HEAT SPEED terminal PARK (2 terminals) unused terminals LINE input voltage (120 VAC) HOT side XMR 24 VAC transformer line voltage HOT side EAC (optional) electronic air cleaner HOT side HUM (optional) humidifier HOT side CIR N circulator blower NEUTRAL terminal LINE N input voltage (120 VAC) NEUTRAL side XMR N 24 VAC transformer line voltage NEUTRAL side EAC N (optional) electronic air cleaner NEUTRAL side HUM N (optional) humidifier NEUTRAL side S flame sensor probe Maximum recommended flame probe wire length is 36 inches. 210 www.white-rodgers.com
INTEGRATED URNACE CONTROLS 50M56U-843 OPERATION OPTION SWITCHES The option switches on the 50M56U-843 control are used to determine the length of the heat delay-to-fan-off period, the mode of operation, and the 2nd stage delay period. The following illustration shows the options and the selections of the switch positions. The switches are shown in the factory default positions. * * *MODE and 2ND STG DLY for Goodman 50M56-289 only HEAT MODE When heat is required, the thermostat will send a call for heat to the control. This starts the controls heating sequence. The ignitor and humidifier (optional) are powered. The ignitor is powered after the pre-purge period. Upon initial application of power, the warm-up time is 17 seconds. The ignitor on-time will then be increased depending on whether or not flame is achieved. The warm-up time is limited to a maximum of 19 seconds. During the first 64 warm-up periods following powerup, the warm-up time may not be less than 17 seconds. In the event of a retry, the warm-up time will be increased by one second and locked in at that duration. Once the warm-up time is locked, it remains fixed until another call for heat results in a retry, in which case the warm-up time is again increased by one second and remains locked. In the event of two successive retry attempts, the warm-up time will be unlocked and set to 19 seconds. If flame is then achieved, the warm-up time will begin adapting again with the next call for heat. If, however, this third attempt fails to achieve flame, the control will go into system lockout. After the ignitor warm-up period, MV LO (first stage) and MV HI (second stage) are both energized to the gas valve. lame must be detected within 4 seconds. If flame is detected, the 30-second HEAT delay-to-fan-on period begins. The circulator and electronic air cleaner (optional) will also energize at this time. 1 Stage operation If the Option Switch MODE (SW1-2) is set to the 1 STG position, both MV LO and MV HI will remain energized. 2 Stage operation (Goodman 50M56-289 Application only) If the Option Switch MODE is set to 2 STG, MV HI will de-energize after 5 seconds, leaving MV LO energized. If the MODE is in the 2 STG position, 2nd STG DLY (SW1-3) will determine the second stage- on delay as follows: 5 MIN On call for heat, the 5 minute 2nd stage recognition timer begins. After the 5-minute delay, the second stage heat (MV HI) is energized. AUTO On call for heat, the automatic second stage will determine the optimum timing between stages for comfort. Auto will adapt the delay to energize MV HI from instantly to up to 12 minutes. When the thermostat is satisfied, the gas valve is de-energized. After proof of flame loss, the heat delay-to-fan-off period begins and the inducer blower remains energized to purge the system for 25 seconds. When the purge is complete, the inducer blower is deenergized. After the delay-to-fan-off period ends, the circulator fan and electronic air cleaner are de-energized. If flame is not detected, both valves are de-energized, the ignitor is turned off, and the 50M56U-843 control goes into the retry sequence. The retry sequence provides a 60-second wait following an unsuccessful ignition attempt (flame not detected). After this wait, the ignition sequence is restarted with an additional 1 second of ignitor warm-up time. If flame is established for more than 10 seconds after ignition, the 50M56U-843 controller will clear the ignition attempt (or retry) counter. If flame is lost after 10 seconds, it will restart the ignition sequence. During burner operation, a momentary loss of power of 50 milliseconds or longer will de-energize the main gas valve. When power is restored, the gas valve will remain de-energized and a restart of the ignition sequence will begin immediately. A momentary loss of gas supply, flame blowout, or a shorted or open condition in the flame probe circuit will be sensed within 2.0 seconds. The gas valve will de-energize and the control will restart the ignition sequence. Recycles will begin and the burner will operate normally if the gas supply returns, or the fault condition is corrected. If the control has gone into system lockout, it may be possible to reset the control by a momentary power interruption of one second or longer. Refer to SYSTEM LOCKOUT EATURES. COOL MODE In a typical system, a call for cool is initiated by closing the thermostat contacts. This energizes the 50M56U-843 control and the compressor. The cool delay-to-fan-on period begins. After the delay period ends, the optional electronic air cleaner is energized, and the circulator fan is energized at cool speed. After the thermostat is satisfied, the compressor is de-energized and the cool mode delay-to-fan-off period begins. After the delay-to-fan-off period ends, the circulator fan and electronic air cleaner (optional) are de-energized. MANUAL AN ON MODE If the thermostat fan switch is moved to the ON position, the circulator fan (low heat speed) and optional electronic air cleaner are energized. When the fan switch is returned to the AUTO position, the circulator fan and electronic air cleaner (optional) are de-energized. SYSTEM LOCKOUT AND DIAGNOSTIC EATURES SYSTEM LOCKOUT EATURES When system lockout occurs, the gas valve is de-energized, the circulator blower is energized at heat speed, and, if flame is sensed, the inducer blower is energized. The diagnostic indicator light will flash or glow continuously to indicate system status. (System lockout will never override the precautionary features.) To reset the control after system lockout, do one of the following: 1. Interrupt the call for heat or cool at the thermostat for at least one second but less than 20 seconds (if flame is sensed with the gas valve de-energized, interrupting the call for heat at the thermostat will not reset the control). 2. Interrupt the 24 VAC power at the control for at least one second. You may also need to reset the flame rollout sensor switch. 3. After one hour in lockout, the control will automatically reset itself. TECHNICAL HELP www.white-rodgers.com 211
50M56U-843 OPERATION INTEGRATED URNACE CONTROLS DIAGNOSTIC EATURES The 50M56U-843 control continuously monitors its own operation and the operation of the system. If a failure occurs, the LED will indicate a failure code as shown below. If the failure is internal to the control, the light will stay off. In this case, the entire control should be replaced, as the control is not field-repairable. If the sensed failure is in the system (external to the control), the LED will flash in the following flash-pause sequences to indicate failure status (each flash will last approximately 0.25 seconds, and each pause will last approximately 2 seconds). DIAGNOSTIC INDICATOR LASH CODES LASH 1 System Lockout (Retries Exceeded) 2 Pressure Switch Stuck Closed 3 Pressure Switch Stuck Open 4 Open High Temperature Limit Switch 5 lame Sensed with Gas Valve De-energized 6 Open Rollout Switch 7 Low lame Sense Signal 8 Ignitor Relay ault Rapid lash Reverse Polarity Continuous On Normal Operation Off Control ailure INSTALLER MUST READ OR PROPER INSTALLATION IMPORTANT: or continuous fan speed operation, one of the unused parked motor taps must be connected to the low heat speed terminal. ailure to do this will result in the blower not energizing in the constant fan mode operation. Refer to figure 1. or all Trane and AMERICAN STANDARD applications only: Install jumper 0151 290600 (included in this package) in the furnace 12 pin connector harness, pin 5 and pin 11 positions. Make sure jumper snaps into the connector securely. Refer to figure 1. AULT RECALL The last five fault codes stored can be displayed on the diagnostic LED. When the control is in standby mode (no call for heat or cool), press the AULT RECALL switch for approximately two seconds or until the diagnostic LED turns off. Release the switch and the LED will remain off for two seconds. Then the fault codes will display beginning with the most recent fault first with a two second pause between codes. After the stored fault codes have all displayed, the LED will remain off for two seconds and then turn on to indicate return to normal status. While displaying the stored fault codes, the control will ignore any new call for heat, cool or fan. AULT CODE RESET The stored fault codes can be erased from memory. When the control is in standby mode (no call for heat or cool), press the AULT RECALL switch for five to ten seconds or until the diagnostic LED begins to rapid flash. When the switch is released, the LED will turn off for two seconds to indicate the codes are erased. After two seconds the LED will turn on to indicate return to normal status. If the switch is held pressed for over ten seconds the rapid flash will stop and the LED will be on to indicate return to normal status. Pin 11 (R10 In) 290600 J Pin 5 (R10 Out) Jumper 0151-290600 (for Trane and American Standard Applications only) TECHNICAL HELP DEINITION O TERMS Auto Restart After one (1) hour of internal or external lockout, the control will automatically reset itself and go into an auto restart purge for 60 seconds. Cool Delay-To-an-Off The period of time between the loss of a call for cool and the deactivation of the blower motor at Cool speed. Cool Delay-To-an-On The period of time after a thermostat demand for cool before energizing the circulator blower motor at Cool speed. lame ailure Response Time (RT) The period of time between loss of the supervised main burner flame and the action to shut off the gas supply. Heat Delay-To-an-Off The period of time between the loss of a call for heat and the deactivation of the blower motor at Heat speed. Heat Delay-To-an-On The period of time between proof of the supervised main burner flame and the activation of the blower motor at Heat speed. Igniter Warm-up Time The length of time allowed for the igniter to heat up prior to the initiation of gas flow. Ignition Activation Period (IAP) The period of time between energizing the main gas valve and deactivation of the ignition means prior to the end of TI. Inter-purge The period of time intended to allow for the dissipation of any unburned gas or residual products of combustion between the failed trial for ignition and the retry period. Post-purge Time The period of time intended to allow for the dissipation of any unburned gas or residual products of combustion at the end of a furnace burner operating cycle. Post-purge begins at the loss of flame sense. Pre-purge Time The period of time intended to allow for the dissipation of any unburned gas or residual products of combustion at the beginning of a furnace operating cycle prior to initiating ignition. Recycles The additional attempts within the same thermostat cycle for ignition after loss of the supervised ignition source or the supervised main burner flame. Retries The additional attempts within the same thermostat cycle for ignition when the supervised main burner flame is not proven within the first trial for ignition period. Trial for Ignition Period (TI) The period of time between initiation of gas flow and the action to shut off the gas flow in the event of failure to establish proof of the supervised ignition source or the supervised main burner flame. 212 www.white-rodgers.com