White Rodgers 50A65-843 Thermostat User Manual
Contents
1. 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 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 18 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 t2. installation or replacement 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 amp EMERSON Failure to comply with the following warnings could result in personal injury or property damage FIRE HAZARD Do not exceed the specified voltage 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 6270E Replaces 37 6270D 0701 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 9 25 VAC 50 60 Hz 0 6 pf Ignitor Relay 2 0 amp 120 VAC 50 60 Hz resistive Flame Current Requirements Minimum curre
3. second This control has an adaptive algorithm that reduces the ignitor temperature to slightly greater than the minimum temperature required to ignite gas in each particular application The control measures the line voltage and determines an initial ignitor temperature setting based on the measurement After each successful ignition the control lowers the ignitor temperature slightly for the next ignition attempt The control continues to lower the ignitor temperature until ignition does not occur and the control goes into retry mode Forthe second attemptto ignite gas within the same call for heat the control increases the ignitor temperature to the value it was on the third previous successful ignition After ignition is successful the control sets the ignition temperature at this value for the next 255 calls for heat after which the control repeats the adaptive algorithm The control is constantly making adjustments to the ignitor temperature to compensate for changes in the line voltage The 80 VAC Silicon Nitride ignitor manufactured by White Rodgers must be used These ignitors are specially designed to operate with the 50A65 s adaptive ignition routine to ensure the most efficient ignitor temperature 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 th
4. T 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 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 50A65 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 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 e
5. White y Rodgers 50A65 843 Universal 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 50A65 843 is an automatic gas interrupted ignition control that employs a microprocessor to continually monitor analyze and control the proper opera tion 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 DESCRIPTION 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
6. ach pause will last approximately 2 seconds 1 flash then pause 2 flashes then pause 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 Low flame sense signal Check ignitor Flame has been sensed when no flame should be present no call for heat 7 flashes then pause 8 flashes then pause Continuous flashing no pause The LED will also flash once at power up MOUNTING HOLE TEMPLATE MOUNTING HOLE TEMPLATE FOR MOUNTING HOLE LOCATIONS 4 172 007 2 plcs 6 402 010 2 plcs Refer to page 3 of the installation instructions for proper installation
7. e 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 6 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 50A65 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 again 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 50A65 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 50A65 controller will clear the ignition attempt or retry counter If flame is lost after 10 seconds it will restartthe ignition sequence This can occur a maximum of 11 times before system lockout A momen
8. he mounting location When drilling the holes take care so that the transformer wiring harness or other system components are not damaged Four 4 318 sheet metal screws are provided to complete the installation Refer to the wiring diagram and wiring table when connecting the 50A65 control to other components of the system 1275 UL approved 105 C rated 18 gauge stranded 216 thick insula tion wire is recommended for all low voltage safety circuit connections Refer to 50A65 specification sheet for recom mended terminals to mate with those on the control UL approved 105 C rated 16 gauge min stranded tes thick insulation wire is recommended for all line voltage connections Refer to 50A65 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 50A65 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 50A65 control There are no other user serviceable parts Additional jumper wires are included in this package and should be used if the original wiring does n
9. nsformer 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 RO1 rollout switch OUTPUT RO2 rollout switch INPUT 1 unused terminal inducer HOT side 4 pin ignitor HOT side connector inducer NEUTRAL side amp harness ignitor NEUTRAL side input voltage 120 VAC HOT side humidifier HOT side CIR N spade terminal circulator blower NEUTRAL terminal input voltage 120 VAC NEUTRAL side HUM N optional humidifier NEUTRAL side 3 16 spade terminal Auxiliary flame sense maximum recommended flame probe wire length is 36 inches OPERATION OPTION SWITCHES The option switches on the 50A65 843 control are used to determine the length of the cool delay to fan off heat delay to fan on and heat delay to fan off periods The following table shows the time periods that will result from the various switch positions OPTION SWITCH POSITIONS COOL delay to fan off 45 sec On 90 sec Off HEAT delay to fan on 30 sec On 45 sec Off Set switch to fan off 3 4 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 50A65 control s heating sequence The inducer blower and optional humidifier are energized and the 768A silicon nitride ignitor is powered within one
10. nt to insure flame detection 1 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 40 to 80 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 2096 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 50A65 843 PRE PURGE IGNITOR WARM UP IGNITION ACTIVATION 1 PERIOD TRIAL FOR IGNITION PERIOD RETRIES VALVE SEQUENCE PERIOD INTERPURGE POST PURGE 15 0 IUE HEAT DELAY TO FAN ON 30 45 60 90 HEAT DELAY TO FAN OFF 120 180 COOL DELAY TO FAN ON EZA COOL DELAY TO FAN OFF AUTO RESET HUMIDIFIER ELECTRONIC AIR CLEANER These times will vary depending on option switch position The control is factory set at 30 seconds heat delay to fan on 180 seconds heat delay to fan off and 45 seconds cool delay to fan off See OPERATION section for further information WARNING FIRE HAZARD Do not exceed the specified voltage Replace existing control with exact model and dash number
11. ot reach the control after mounting Refer to the furnace wiring diagram for proper connection of the wires Some applications may require connection to terminal E33 located in the middle of the contol cover If the control being replaced does not have this connection it is not needed in the application and connection to terminal E33 is not required Trane application Jumper wire 151 2906 provided with control must be installed the furnace from R01 to R02 of the 12 pin connector TYPICAL SYSTEM WIRING DIAGRAM HOT NEUTRAL LINE aiuit LINE 24 VAC CLASS II TRANSFORMER TH 24 VAC 50A65 843 INDUCER IGNITOR HUMIDIFIER ELECTRONIC AIR CLEANER COMPRESSOR CONTACTOR THERMOSTAT PRESSURE SWITCH N O OO HIGH LIMIT AUX HIGH N C LIMIT N C Low Voltage 24 VAC Line Voltage 120 VAC C Normally closed switch 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 tra
12. tary 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 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 ten seconds 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 50A65 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 LOCKOU
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