White Rodgers 50A55-438 Thermostat User Manual
Contents
1. 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 s holes for mounting control To ensure proper mounting hole locations there is a mounting hole temp2. remains locked In the event of two successive retry attempts the warm up time will be unlocked and setto 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 circulator fan is energized at heat speed If there is an optional electronic air cleaner on the system the electronic air cleaner is also ener gized When the thermostat is satisfied the gas valve is de energized After proof of flame loss the delay to fan off period begins and the inducer blower remains energized to purge the System for 5 seconds When the purge is complete the inducer blower and humidifier are de energized 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 50A55 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 2 seconds of ignitor warm up time If this ignition attempt i
3. sense signal 7 flashes then pause 8 flashes then pause 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
4. FIER ELECTRONIC AIR CLEANER COMPRESSOR CONTACTOR QQ HIGH L MIT AUX HIGH N C LIMIT N C 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 FP 12 pin flame sensor probe PS connector pressure switch INPUT HLI amp harness high limit INPUT HLO high limit OUTPUT GND MUST BE RELIABLY GROUNDED TO CHASSIS 3 unused terminals inducer HOT side 4 pin ignitor HOT side connector inducer NEUTRAL side amp harness n ignitor NEUTRAL side input voltage 120 VAC HOT side circulator blower NEUTRAL terminal input voltage 120 VAC NEUTRAL side electronic air cleaner NEUTRAL side maximum recommended flame probe wire length is 36 inches OPERATION OPTION SWITCHES The option switches on the 50A55 438 control are used to determine the length of the cool delay to fan off and heat del
5. WHITE RODGERS 50A55 438 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 438 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 replaceme
6. ay to fan off periods The following tables show the time periods that will result from the various switch positions OPTION SWITCH POSITIONS COOL delay to fan off 0 sec 80 sec Set switch to fan off 2 3 60 sec 100 sec 140 sec 180 sec 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 These controls have an adaptive algorithm that adjusts the duration of the ignitor warm up for the purpose of extending 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 first 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 in a retry In the event of a retry the warm up time will be increased by two seconds and locked 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
7. e 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 The LED light on the control will flash slowly one flash per second if there are no failures and no call for heat If there is a call for heat the LED will flash quickly one flash per half second 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 LED is continuously off there may be no power to the control the fuse on the control may be open or there may be a failure in the control 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 2 flashes then pause 3 flashes then pause 4 flashes then pause 5 flashes then pause 6 flashes then pause System lockout no flame Pressure switch problem Thermal protection device open Flame sensed with gas valve off 115 Volt AC power reversed im proper ground Gas valve circuit error Low flame
8. for cool is initiated by closing the thermostat contacts This energizes the 50A55 control The compressor and optional electronic air cleaner are energized and the circulator fan is energized at cool speed After the thermostat is satisfied the compressor is de energized and the optional cool mode delay to fan off period begins After the optional 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 circulatorfan heat 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 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 indica tor light will flash or glow continuously to indicate system status System lockout will never override any precautionary features 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 th
9. late 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 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 a 3 Amp automotive type fuse If the fuse is 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 LINE 120 VAC l l 24 VAC CLASS II TRANSFORMER TH INDUCER IGNITOR HUMIDI
10. lay 1 5 amp 9 25 VAC 50 60 Hz 0 6 pf Ignitor Relay 6 0 amp 9420 VAC 50 60 Hz resistive 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 Liquefied Petroleum and LP Gas Air Mixtures are all approved for use TIMING SPECIFICATIONS All times are in seconds unless noted otherwise PRE PURGE TRIAL FOR IGNITION PERIOD IGNITION ACTIVATION PERIOD RETRIES VALVE SEQUENCE PERIOD INTERPURGE POST PURGE LOCKOUT TIME DELAY TO HEAT ON DELAY TO HEAT OFF DELAY TO COOL ON DELAY TO COOL OFF MINIMUM IGNITOR WARM UP MAXIMUM IGNITOR WARM UP INITIAL IGNITOR WARM UP 1st 64 attempts HUMIDIFIER ELECTRONIC AIR CLEANER 50A55 438 45 140 180 11 ES These times will vary depending on option switch position The control is factory set at 0 sec delay to cool off and 100 sec delay to heat off See OPERATION section for further information
11. nt 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 DIVISION EMERSON ELECTRIC CO 9797 REAVIS ROAD ST LOUIS MISSOURI 63123 5398 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 6102B Replaces 37 6102A 0009 SPECIFICATIONS ELECTRICAL RATINGS 77 F 25 C Input Voltage 25 VAC 50 60 Hz Max Input Current 25 VAC 0 45 amp Relay Load Ratings Valve Re
12. s 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 ten recycles After ten 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 11 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 probe circuit will be sensed within 2 0 seconds The gas valve will de energize and the control will restartthe ignition sequence A recycle 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
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