White Rodgers 50a55-286 Thermostat User Manual
Contents
1. This control is a precision instrument and should be handled carefully Rough handling or distorting compo nents could cause the control to malfunction CONTENTS Description Precautions Specifications Installation Mounting amp Wiring Operation WHITE RODGERS DIVISION EMERSON ELECTRIC CO Ti 9797 REAVIS ROAD EMERSON ST LOUIS MISSOURI 63123 5398 DESCRIPTION To prevent electrical shock and or equipment damage disconnect electric power to system at main fuse or circuit breaker box until installation is complete Label all wires prior to disconnection when ser vicing controls Wiring errors can cause im proper and dangerous operation This control is not intended for use in locations where it may come in contact with water Suit able protection must be provided to shield the control from exposure to water dripping spray ing rain etc Do not use on circuits exceeding specified volt age Higher voltage will damage control and could cause shock or fire hazard Do not short out terminals on gas valve or pri mary control to test Short or incorrect wiring will damage thermostat and could cause personal injury and or property damage PART NO 37 6101A Printed in U S A 9919 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 Relay 1 5 amp 25 VAC 50 60 Hz 0 6 pf Ignitor Relay 6 0 amp2. 1 4 spade terminal electronic air cleaner NEUTRAL side 1 4 spade terminal humidifier NEUTRAL side maximum recommended flame probe wire length is 36 inches OPERATION OPTION SWITCHES The option switches on the 50A55 286 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 set position HEAT MODE In atypical system a call for heat is initiated by closing the thermostat contacts This starts the 50A55 control s heat ing sequence The inducer blower and optional humidifier are energized and the ignitor is powered The ignitor is then allowed to warm up for 17 seconds The 120 VAC ignitors with a 17 second warm up time manufactured by Carborundum Ignitor Systems Inc or Norton must be used These ignitors are specially designed to heat up quickly at a low voltage condition without overheating at a high voltage condition At the end of the ignitor warm up time both valves in the 36E manifold gas valve are opened Flame must be detected within 7 seconds If flame is detected the delay to fan on period begins After the delay to fan on period ends the optional elec tronic air cleaner is powered and the circulator fan is energized at heat speed When the thermostat
3. 120 VAC 50 60 Hz resistive Flame Current Requirements Minimum current to insure flame detection 1 wa DC Maximum current for non detection 0 1 wa DC Maximum allowable leakage resistance 100 Mohms 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 Liquid Petroleum and LP Gas Air Mixtures are all approved for use TIMING SPECIFICATIONS All times are in seconds unless noted otherwise 50A55 286 PRE PURGE INITIAL IGNITOR RETRY IGNITOR IGNITION ACTIVATION PERIOD TRIAL FOR IGNITION PERIOD RETRIES VALVE SEQUENCE PERIOD INTERPURGE POST PURGE LOCKOUT TIME DELAY TO HEAT ON 30 60 90 DELAY TO HEAT OFF 450 480 DELAY TO COOL ON DELAY TO COOL OFF AUTO RESET HUMIDIFIER ELECTRONIC AIR CLEANER This time will vary depending on option switch position The control is factory set at 60 sec delay to heat off See OPERATION section for further information MOUNTING AND WIRING Do not use on circuits exceeding specified voltage Higher voltage will damage control and could cause shock or fire hazar
4. 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 ener gize 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 Otherwise 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 atypical system a call 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 cool mode delay to fan off period begins After the cool delay to fan off period ends the circulator fan and electronic air cleaner 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 position the circulator fan and electronic air
5. each flash will last approximately 0 25 seconds and each pause will last approximately 2 seconds If more than one failure is detected the LED will alternate through all the failure codes that apply Continuous flashing no pause Low flame sense signal 1 flash then pause Lockout caused by flame sensed when there should be no flame Pressure switch stuck closed Pressure switch stuck open 2 flashes then pause 3 flashes then pause 4 flashes then pause High limit open 5 flashes then pause Rollout switch open or rollout sensed 6 flashes then pause Lockout caused by pressure switch opening 4 times in one cycle Lockout caused by no ignition after 3 trials Lockout caused by loss of flame 5 times in one heating cycle 115 Volt AC power reversed improper ground 12 flashes then pause Ignitor relay sense error The LED will also flash once at power up 7 flashes then pause 8 flashes then pause 9 flashes then pause Will automatically restart from lockout after one hour All other conditions need to be cleared for the control to resume normal operation 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
6. WHITE RODGERS 50A55 286 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 286 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 thermostat and flame sensing element initiate automatic ignition of the burner sensing of the flame and system shut off during normal operation These controls incorporate system fault analysis for quick gas flow shut off coupled with automatic ignition retry upon sensing a fault correction y GENERAL PRECAUTION Application of this type of control may cause flame rollout on initial start up and could cause personal injury and or property damage Replace only with exact model number includ ing dash number Failure to use exact replace ment control could cause personal injury and or property damage 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
7. cleaner optional are de energized SYSTEM LOCKOUT AND DIAGNOSTIC FEATURES SYSTEM LOCKOUT FEATURES When system lockout occurs the gas valve is de ener gized 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 continu ously 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 atleast one second but less than 20 seconds if flame is sensed with the gas valve de energized interrupt ing 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 opera tion 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
8. d To prevent electrical shock and or equipment damage disconnect electric power to system at main fuse or circuit breaker box until installation is complete Failure to earth ground the appli ance or reversing the neutral and hot wire con nection to the line can cause shock hazard Shut off main gas to heating system until instal lation is complete Route and secure all wiring as far from flame as practical to prevent fire and or equipment damage To prevent damage to the transformer system components or wiring harness take care when drilling new mounting holes Failure to do somay result in electrical shock fire hazard or equip ment damage INSTALLATION All wiring should be installed according to local and national electrical codes and ordinances The control must be secured to an area that will experi ence a minimum of vibration and remain below the maxi mum ambient temperature rating of 175 F The control is approved for minimum 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 har ness or system components After finding a suitable location drill four 4 holes for mounting control To ensure proper mounting hole locations there is a mount ing hole template on page 8 of this instruction sheet Detach the page with the template from the instruction shee
9. is satis fied 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 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 15 second wait following an unsuccessful ignition attempt flame not detected After this wait the ignition sequence is restarted with an additional 11 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 amomentary loss of power of 50 milliseconds or longer will de energize the main gas valve
10. le TRANSFORMER Lo CIRCULATOR BLOWER ELECTRONIC AIR CLEANER COMPRESSOR CONTACTOR OO OO HIGH LIMIT AUX HIGH N C LIMIT N C THERMAL ROLLOUT N C SENSOR gt r L Low Voltage 24 VAC Line Voltage 120 VAC N C Normally closed switch N O Normally open switch 50A55 TERMINAL MV 2 terminals TR TH FP PS HLI HLO GND unused terminal COOL HEAT PARK LINE XFMR EAC optional HUM CIR N LINE N XFMR N EAC N optional HUM N optional 2 terminals optional TYPICAL SYSTEM WIRING TABLE TYPE 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 gas valve both gas solenoids are connected in parallel 24 VAC transformer low voltage COMMON side 24 VAC transformer low voltage HIGH side rollout switch OUTPUT rollout switch INPUT flame sensor probe pressure switch INPUT high limit INPUT high limit OUTPUT MUST BE RELIABLY GROUNDED TO CHASSIS Terminal block with captive screws 12 pin connector amp harness inducer HOT side ignitor HOT side inducer NEUTRAL side ignitor NEUTRAL side V4 spade terminal Ya spade terminal 4 pin connector amp harness
11. t and apply it to the mounting location When drilling the holes take care so that the transformer wiring har ness 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 con necting the 50A55 control to other components of the system UL approved 105 C rated 18 gauge stranded 4 thick insulation wire is recommended for all low voltage safety circuit connections Refer to 50A55 specification sheet for recommended 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 rec ommended terminals to mate with those on the control After installation or replacement follow appliance manufacturer s recommended installation or service in structions 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 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 ioKe LINE a 24 VAC CLASS II
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