White Rodgers 50A55-285 Thermostat User Manual
Contents
1. 4 1 2 holes for mounting control To ensure proper mounting hole locations there is a mounting hole template on page 8 of this instruction sheet Detach the page with the template from the instruction sheet and apply it to the mounting location When drilling the holes take care so that the transformer wiring harness or other system components are not damaged Four 4 8 sheet metal screws are provided to complete the installation Refer to the wiring diagram and wiring table when connecting the 50A55 control to other components of the system UL approved 105 C rated 18 gauge stranded 4 thick insula tion wire is recommended for all low voltage safety circuit connections Refer to 50A55 specification sheet for recom mended terminals to mate with those on the control UL approved 105 C rated 16 gauge min stranded 4 thick insulation wire is recommended for all line voltage connections Refer to 50A55 specification sheet for recommended terminals to mate with those on the control After installation or replacement follow appliance manufacturer s recommended installation or service instructions to ensure proper operation The 50A55 has only one serviceable part an automotive type fuse which protects the low voltage transformer from damage if its output is short circuited If the fuse has opened up remove whatever caused the short circuit and replace the fuse with only a3 Amp automotive type fuse If the fuse is2. 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 FLA 3 5 LRA 120 VAC Circulator Relay 14 5 FLA 25 0 LRA 120 VAC Flame Current Requirements Minimum current to insure flame detection 1 ua DC Maximum current for non detection 0 1 ua DC Maximum allowable leakage resistance 100 M ohms Measured with a DC microammeter in the flame probe lead OPERATING TEMPERATURE RANGE 40 to 175 F 40 to 80 C HUMIDITY RANGE 5 to 93 relative humidity non condensing MOUNTING Surface mount multipoise Timing Specs 60 Hz maximum Flame Establishing Time 0 8 sec Flame Failure Response Time 2 0 sec At 50 Hz all timing specifications should be increased by 20 Gases Approved Natural Manufactured Mixed Liquified Petroleum and LP Gas Air Mixtures are all approved for use TIMING SPECIFICATIONS All times are in seconds unless noted otherwise 50A55 285 PRE PURGE INITIAL IGNITOR WARM UP 1st 64 attempts MINIMUM IGNITOR WARM UP MAXIMUM IGNITOR WARM IGNITION ACTIVATION PERIOD TRIAL FOR IGNITION PERIOD RETRIES VALVE SEQUENCE PERIOD INTERPURGE POST PURGE LOCKOUT TIME HEAT DELAY TO FAN ON 30 HEAT DELAY TO FAN OFF 60 90 120 180 COOL DELAY TO FAN ON COOL DELAY TO FAN OFF AUTO RESET HUMIDIFIER ELECTRONIC AIR YES CLEANER These times will vary depending on option switch position The control
3. is factory set at 90 sec HEAT delay to fan off See OPERATION section for further information A WARNING FIRE 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 Label all wires before disconnection when servic ing 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 INSTALLATION MOUNTING AND WIRING All wiring should be installed 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 175 F The control is approved for mini mum ambient temperatures of 40 F 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. PEED terminal HEAT spade terminal circulator blower HEAT SPEED terminal PARK 2 terminals spade terminal unused circulator blower terminals XFMR spade terminal 24 VAC transformer line voltage HOT side LINE spade terminal input voltage 120 VAC HOT side EAC optional spade terminal electronic air cleaner HOT side humidifier NEUTRAL side maximum recommended flame probe wire length is 36 inches HUM optional spade terminal humidifier HOT side OPERATION OPTION SWITCHES The option switches on the 50A55 285 control are used to determine the length of the heat delay to fan off periods The following table shows the time periods that will result from the various switch positions OPTION SWITCH POSITIONS HEAT delay Set switch to fan off 1 2 60 sec 90 sec 120 sec 180 sec Factory setting HEAT MODE In a typical system a call for heat is initiated by closing the thermostat contacts This starts the 50A55 control s heating sequence The inducer blower and optional humidifier are energized and the ignitor is powered within one second This controller has an adaptive algorithm that adjusts the dura tion of the ignitor warm up to extend ignitor life Upon initial application of power the warm up time is 17 seconds The ignitor on time will then be increased or decreased depending on whether or not flame is achieved The warm up time is limited to a maximum of 21 seconds During the fi
5. WHITE RODGERS 50A55 285 Integrated Furnace Control INSTALLATION INSTRUCTIONS Operator Save these instructions for future use FAILURE TO READ AND FOLLOW ALL INSTRUCTIONS CAREFULLY BEFORE INSTALLING OR OPERATING THIS CONTROL COULD CAUSE PERSONAL INJURY AND OR PROPERTY DAMAGE The 50A55 285 is an automatic gas interrupted ignition control that employs a microprocessor to continually monitor analyze and control the proper operation of the gas burner inducer and fan Signals interpreted during continual surveillance of the thermo stat and flame sensing element initiate automatic ignition of the burner sensing of the flame and system shut off during normal operation DESCRIPTION These controls incorporate system fault analysis for quick gas flow shut off coupled with automatic ignition retry upon sensing a fault correction 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 condi tioning 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 Following installation or replac
6. ducer blower and humidifier are de energized After the delay to fan off pe riod 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 50A55 control goes into the retry se quence The retry sequence provides a 60 second wait follow ing an unsuccessful ignition attempt flame not detected After this wait the ignition sequence is restarted with an additional 2 seconds of ignitor warm up time If this ignition attempt is unsuccessful one more retry will be made before the control goes into system lockout If flame is detected then lost the 50A55 control will repeat the initial ignition sequence for a total of four recycles After four unsuccessful recycle attempts the control will go into system lockout If flame is established for more than 10 seconds after ignition the 50A55 controller will clear the ignition attempt or retry counter If flame is lost after 10 seconds it will restart the ignition sequence This can occur a maximum of five times before system lockout 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
7. e 3 flashes then pause 4 flashes then pause 5 flashes then pause 6 flashes then pause System lockout Pressure switch stuck closed Pressure switch stuck open Open limit switch Open rollout switch 115 Volt AC power reversed Im proper ground 7 flashes then pause Low flame sense signal Continuous flashing Flame sensed with gas valve no pause off The LED will also flash once at power up MOUNTING HOLE TEMPLATE MOUNTING HOLE TEMPLATE FOR MOUNTING HOLE LOCATIONS 4 172 007 2 ples 6 402 010 2 ples Refer to page 3 of the installation instructions for proper installation
8. e 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 indica tor light will flash or glow continuously to indicate system status System lockout will never override the precautionary fea tures To reset the control after system lockout do one of the following 1 Interruptthe call for heat or cool at the thermostat for atleast 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 DIAGNOSTIC FEATURES The 50A55 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 on continuously 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 1 flash then pause 2 flashes then paus
9. ement follow manufacturer s recommended installation service instructions to ensure proper CAUTION Do not short out terminals on gas valve or primary control Short or incorrect wiring may damage the thermostat CONTENTS Description Precautions Specifications Installation Mounting amp Wiring Operation Mounting Hole Template WHITE RODGERS EMERSON ELECTRIC CO 9797 REAVIS ROAD ST LOUIS MISSOURI 63123 5398 www white rodgers com Printed in U S A Failure to comply with the following warnings could result in personal injury or property damage FIRE 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 servic ing 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 PART NO 37 6100C Replaces 37 6100B 0150 SPECIFICATIONS ELECTRICAL RATINGS 77 F 25 C Input Voltage 25 VAC 50 60 Hz Max Input Current 25 VAC 0 45 amp Relay Load
10. not the cause of the control s problem replace the entire 50A55 control There are no other user serviceable parts TYPICAL SYSTEM WIRING DIAGRAM HOT NEUTRAL LINE abode LINE O 24 VAC CLASS II TRANSFORMER ieee BLOWER ELECTRONIC AIR CLEANER COMPRESSOR CONTACTOR THERMOSTAT PRESSURE SWITCH N O OOD OO HIGH LIMIT AUX HIGH N C LIMIT N C ROLLOUT Low Voltage 24 VAC Line Voltage 120 VAC N C Normally closed switch N O Normally open switch TYPICAL SYSTEM WIRING TABLE TERMINAL TYPE CONNECTION low voltage thermostat W terminal or equivalent Terminal low voltage thermostat G terminal or equivalent block with low voltage thermostat R terminal or equivalent captive low voltage thermostat Y terminal or equivalent screws 2nd wire from Y terminal goes to 24 VAC HOT side of compressor contactor coil 24 VAC COMMON side of compressor contactor coil MV 2 terminals gas valve both gas solenoids are connected in parallel TR 24 VAC transformer low voltage COMMON side TH 24 VAC transformer low voltage HIGH side rollout switch OUTPUT 12 pin rollout switch INPUT FP connector flame sensor probe PS amp harness pressure switch INPUT HLI high limit INPUT HLO high limit OUTPUT GND MUST BE RELIABLY GROUNDED TO CHASSIS unused terminal IND 2 pin inducer HOT side connector a i IGN amp harness ignitor HOT side COOL spade terminal circulator blower COOL S
11. 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 before the last ignition attempt Other wise the control will go into system lockout 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 FEATURES COOL MODE In a typical system a call for cool is initiated by closing the thermostat contacts This energizes the 50A55 control and the compressor The cool delay to fan on period begins After the delay period ends the optional electronic air cleaner is ener gized 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 FAN ON MODE If the thermostat fan switch is moved to the ON position the circulator fan cool speed and optional electronic air cleaner are energized When the fan switch is returned to the AUTO posi tion the circulator fan and electronic air cleaner optional are de energized SYSTEM LOCKOUT AND DIAGNOSTIC FEATURES SYSTEM LOCKOUT FEATURES When system lockout occurs th
12. rst 64 warm up periods following power up the warm up time may not be less than 17 seconds Upon a call for heat if the warm up time has not been locked it willbe decreased by one second This reduction of the ignitor on time will continue until flame fails to be achieved resulting ina retry In the event of a retry the warm up time will be increased by two seconds 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 two seconds and remains locked In the event of two successive retry attempts the warm up time will be unlocked and set to 21 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 At the end of the ignitor warm up time both valves in the 36E manifold gas valve are opened Flame must be detected within 4 seconds If flame is detected the delay to fan on period begins After the delay to fan on period ends the optional electronic air cleaner is energized and the circulator fan is energized at heat speed 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 15 seconds When the purge is complete the in
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