Lennox 80UHG Series, Service Literature

Page 1: ...itrogen Oxides NOx Standards and California Sea8 sonal Efficiency requirements All units use a redundant gas valve to assure safety shut off as required by A G A or C G A Units may be installed in upf...

Page 2: ...46J66 15 lbs 8 kg SPECIFICATIONS Model No 80UHG3 4 X 100 80UHG4 5 X 100 80UHG3 4 X 120 80UHG4 5 X 120 Input Btuh kW 100 000 29 3 120 000 35 2 Output Btuh kW 82 000 24 0 98 400 28 8 A F U E 80 1 80 0...

Page 3: ...375 20 50 1370 645 1180 555 980 460 790 375 25 62 1350 635 1160 545 970 460 780 370 30 75 1330 630 1140 540 955 450 770 365 40 100 1280 605 1095 515 925 435 750 355 50 125 1210 570 1040 490 900 425 72...

Page 4: ...lace Also see Filter Air Resistance table FILTER AIR RESISTANCE cfm L s in w g Pa 0 0 0 00 0 200 95 0 01 2 400 185 0 03 7 600 280 0 04 10 800 375 0 06 15 1000 470 0 09 22 1200 560 0 12 30 1400 655 0 1...

Page 5: ...BOX SECONDARY LIMITS FRONT ACCESS PANEL DOOR INTERLOCK SWITCH CONTROL BOARD TRANSFORMER PROVE SWITCH 80UHG PARTS IDENTIFICATION FIGURE 2 HEAT EXCHANGER COMBUSTION AIR INDUCER MANIFOLD ROLLOUT SWITCH...

Page 6: ...protect the furnace s electronic controls Precautions will help to avoid control exposure to electrostatic dis charge by putting the furnace the control and the technician at the same electrostatic po...

Page 7: ...be open the combustion air inducer is energized When the differ8 ential in the prove switch is great enough the prove switch closes and a 15 second pre purge begins If the prove switch is not proven...

Page 8: ...ed OR Pressure switch closed prior to activation of combustion air blower ALTERNATING SLOW FLASH ALTERNATING SLOW FLASH Watchguard burners fail to ignite SLOW FLASH OFF Flame sensed without gas valve...

Page 9: ...nal is sensed NOTE The 80UHG furnace contains electronic components that are polarity sensitive Make sure that the furnace is wired correctly and is properly grounded PARK TERMINAL DESIGNATIONS COOL H...

Page 10: ...ts If the primary or secondary heating limits open the control de energizes the main gas valve and combustion air blower while the indoor blower remains en ergized When the limit automatically resets...

Page 11: ...is a heating demand On Flash Primary or Secondary Limit Switch Open Auto Reset Switch Flash Off Pressure Switch Watchguard pressure switch opened during operation Alternate Flash Alternate Flash Watch...

Page 12: ...P 1 2 1 3 1 4 5MFD 370V 5MFD 370V 7 5MFD 370V 80UHG5 6 80UHG4 80UHG4 5 1 2 7 5MFD 370V 3 4 40MFD 370V 3 4 40MFD 370V FIGURE 11 SUPPLY AIR BLOWER AND SECONDARY LIMITS Front Bottom Right Left Top Back B...

Page 13: ...t point will be printed on the limit Two limits are supplied in each furnace 80UHG3 80UHG4 and 80UHG4 5 model units built prior to Apri 1999 will have one each of style shown in figures 13 and 14 If s...

Page 14: ...ODEL SHOWN FIGURE 18 SPARK ELECTRODE SPARK ELECTRODE TO BURNER GAP 80UHG 1 MODEL SHOWN BURNER FLAME SENSOR TO BURNER GAP BURNER FLAME SENSOR SPARK ELECTRODE 5 16 in 7 mm 5 16 in 7 mm 13 Combustion Air...

Page 15: ...ard 80UHG 1 units are equipped with a direct spark igni tion system Do not attempt to light manually 1 STOP Read the safety information at the beginning of this section 2 Set thermostat to lowest sett...

Page 16: ...to check for gas leaks D Testing Gas Supply Pressure When testing supply gas pressure connect test gauge to inlet pressure tap field provided See figure 20 Check gas line pressure with unit firing at...

Page 17: ...roamp DC meter is needed to check the flame signal on the ignition control Flame microamp signal is an electrical current which passes from the furnace control through the sensor during unit opera tio...

Page 18: ...mperature is too low decrease blower speed If temperature is too high first check the firing rate Provided the firing rate is acceptable in crease blower speed to reduce temperature To change blower s...

Page 19: ...in the heat exchanger clean ing is not recommended Removal is for inspection only NOTE Use papers or protective covering in front of fur nace while cleaning furnace To clean burners 1 Remove screws ho...

Page 20: ...ting in gas leaks fire or explosion C Supply Air Blower 1 Check and clean blower wheel 2 Motors used on the Lennox 80UHG series units are permanently lubricated and need no further lu brication D Flue...

Page 21: ...n control energizes the combustion air inducer B6 When the combustion air inducer nears full speed combustion air prove switch S18 closes Switch must close within 2 1 2 minutes or control goes into 5...

Page 22: ...OR BLOWER WITH DELAY OFF DIAG CODE 1 OFF 2 FLASHING C A B PRESSURE SWITCH OPEN IS 5 MINUTE RESET PERIOD COMPLETE INDOOR AIR BLOWER ON Fixed 45 second delay PRIMARY SECONDARY LIMITS MONITORED IN HEAT C...

Page 23: ...RMOSTAT CONTROL ENERGIZES SYSTEM FAN AT HEATING SPEED ACC TERMINAL ENERGIZED THERMOSTAT CALLS FOR HEAT LED Slow flash rate REMAINS UNCHANGED THROUGHOUT SEQUENCE THERMOSTAT CALLS FOR COOLING SYSTEM FAN...

Page 24: ...hguard Pressure Switch delay Once S18 closes a 15 second pre purge follows 4 SureLight control energizes ignitor A 20 second warm up period begins 5 Gas valve opens for a 4 second trial for ignition i...

Page 25: ...AS VALVE OFF COMBUSTION AIR INDUCER ON INDOOR BLOWER ON HEATING SPEED LED 1 SLOW FLASH LED 2 OFF GAS VALVE OFF COMBUSTION AIR INDUCER OFF INDOOR BLOWER OFF WITH DELAY LED 1 OFF LED 2 SLOW FLASH Sequen...

Page 26: ...CONTROL FAILED TO SENSE FLAME FOR FIVE CONSECUTIVE TRIES DURING A SINGLE HEAT DEMAND WATCHGUARD MODE GAS VALVE OFF COMBUSTION AIR INDUCER OFF INDOOR BLOWER OFF WITH DELAY LEDs SIGNAL WATCHGUARD FAILU...

Page 27: ...D SLOW FLASH RATE REMAINS UNCHANGED THROUGHOUT COOLING CYCLE THERMOSTAT CALLS FOR COOLING COMPRESSOR CONTACTOR AND SYSTEM FAN ENERGIZED WITH 0 SECOND DELAY COOLING SPEED EAC H TERM ENERGIZED COMPRESSO...

Page 28: ...THERMOSTAT CALLS FOR HEAT W THERMOSTAT CALLS FOR COOLING THERMOSTAT OPENS SYSTEM FAN SWITCHED TO COOL H SPEED EAC H TERM REMAINS ON THERMOSTAT OPENS MANUAL FAN SELECTION MADE AT THERMOSTAT CONTROL G...

Page 29: ...he roll out switch by pushing the top button ACTION 2 Determine the cause of the roll out switch activation before leaving furnace code 1 2 2 Roll out switch failure ACTION 1 Check continuity across r...

Page 30: ...WER DOES NOT ENERGIZE Condition Possible Cause Corrective Action Comments 2 1 Unit operates with a cooling or con tinuous fan demand Combustion air inducer will not start with a Heating demand Diagnos...

Page 31: ...e pressure switch failure code 2 5 minutes after heating demand 3 1 2 Pressure switch does not close due to obstructions in the pressure lines ACTION 1 Remove any obstructions from the the pressure li...

Page 32: ...ch code LED 1 Off LED 2 Slow Flash 5 1 1 Low pressure differential at the pres sure switch ACTION 1 Check for restricted exhaust vent Remove all blockage ACTION 2 Check for proper vent sizing See inst...

Page 33: ...3 4 Burners are not properly located in the burner box ACTION 1 Check that the burners are firing into the center of the heat exchanger openings Cor rect the location of the burners if necessary 5 4...

Page 34: ...Action Comments 7 0 Indoor blower fails to operate in continuous fan cooling or heating mode 7 1 1 Miswiring of furnace or improper con nections at control or indoor blower motor ACTION 1 Correct wir...