Lennox G50UHi Series Unit Information Download

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Page 24

SURELIGHT CONTROL

HEATING SEQUENCE OF OPERATION

NORMAL HEATING MODE

ABNORMAL HEATING MODE

CONTROL SELF−CHECK OKAY?

BURNER OFF?

(CONTINUOUS FLAME CHECK)

NORMAL OPERATION:

LED #1 −− SLOW FLASH
LED #2 −− SLOW FLASH

YES

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER DELAY OFF.

LED #1 ON
LED #2 ON

(RESET CONTROL BY TURNING MAIN POWER OFF.)

POLARITY REVERSED.

LED #1 −− FAST FLASH

LED #2 −− SLOW FLASH

POWER ON

COMBUSTION AIR INDUCER ON FOR 1 SECOND.

(Control board 9748)

TURN INDUCER ON FOR 1 SECOND.

IS POLARITY REVERSED? (Control board 9748)

ROLLOUT SWITCH CLOSED?

THERMOSTAT CALLS FOR HEAT:

LED #1 −− FAST FLASH
LED #2 −− FAST FLASH

IS COMBUSTION AIR

PROVE SWITCH OPEN?

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH DELAY.

LED #1 −− ON. LED #2 −− SLOW FLASH.

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.

GAS 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

(Sequence holds until PROVE switch

closes or thermostat resets control.)

YES

IS THERE

PROPER GROUND?

IS VOLTAGE

ABOVE 75 VOLTS?

LED#1 AND LED#2 ALTERNATING FAST

FLASH. SIGNAL HOLDS UNTIL VOLTAGE

RISES ABOVE 75 VOLTS.

YES

IS COMBUSTION AIR INDUCER ENERGIZED?

(ACCESSORY TERMINAL IS ENERGIZED WITH C.A.I.)

HAS COMBUSTION AIR PROVE SWITCH

CLOSED IN 2.5 MINUTES?

YES

PROVE SWITCH IS IN WATCHGUARD MODE.

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH DELAY.

LED #1 −− OFF. LED #2 −− SLOW FLASH.

IS 5-MINUTE RESET PERIOD COMPLETE?

15-SECOND COMBUSTION AIR INDUCER PREPURGE

INITIATED BY CLOSED PROVE SWITCH.

YES

CONTINUED NEXT PAGE

YES

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

INDOOR BLOWER ON.

LED #1 ALTERNATING FAST FLASH

LED#2 ALTERNATING FAST FLASH

CHECK FOR BROKEN IGNITOR OR

OPEN IGNITOR CIRCUIT

LED#1 AND LED#2
ALTERNATING FAST
FLASH. SIGNAL
HOLDS UNTIL UNIT IS
PROPERLY GROUND.

TABLE 19

FLAME SENSE SIGNAL

97L48

SureLight Control Board

69M15

Normal

Low

Drop Out

0.31

0.25 − 0.30

0.24

0.61

0.21 − 0.60

0.20

Control board 69M15 LED #1 = DS1, LED #2 = DS2
Control board 97L48 LED #1 = DIAG1 LED #2 = DIAG2

Summary of Contents for G50UHi Series

Page 1: ...ned in this manual are presented as a recom mendation only and do not supersede or replace local or state codes In the absence of local or state codes the guidelines and procedures outlined in this ma...

Page 2: ...gle 44J22 Ten Pack 66K63 1 16 x 25 x 1 406 x 635 x 25 EZ Filter Base Catalog Number Ship Wt 73P55 6 lbs 3 kg 73P56 7 lbs 3 kg 73P56 7 lbs 3 kg Base Dimensions H x W x D 4 x 14 1 4 x 28 5 8 in 102 x 36...

Page 3: ...8 m 15M22 15M22 LPG Propane Kit 0 7500 ft 0 2286 m 45L60 45L60 p 7501 10 000 ft 2286 3048 m 47M81 47M81 Horizontal Support Frame Kit Shipping Weight 56J18 18 lbs 8 kg 56J18 18 lbs 8 kg Relay Kit 56L68...

Page 4: ...060 500 475 985 465 445 875 415 390 790 375 330 690 325 290 525 250 225 0 9 225 935 440 435 930 440 435 885 420 410 825 390 390 740 350 350 675 320 295 510 240 235 NOTES All air data is measured exter...

Page 5: ...375 650 420 1075 505 290 0 4 100 2055 970 1015 1945 920 890 1825 860 775 1680 790 645 1525 720 545 1375 650 455 1075 505 310 0 5 125 2010 950 1025 1895 895 890 1810 855 810 1680 795 690 1515 715 580 1...

Page 6: ...Page 6 FIGURE 1...

Page 7: ...HORIZONTAL POSITION BLOWER ACCESS PANEL HEAT EXCHANGER ASSEMBLY BURNER ASSEMBLY COMBUSTION AIR INDUCER SURELIGHT CONTROL BOARD GAS VALVE BURNER ACCESS PANEL BLOWER ASSEMBLY PRIMARY LIMIT BLOWER CONTRO...

Page 8: ...utions will help to avoid control exposure to electrostatic dis charge by putting the furnace the control and the technician at the same electrostatic poten tial Neutralize electrostatic charge by tou...

Page 9: ...tion air inducer is energized When the differential 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 within 2 1 2 minutes...

Page 10: ...NEOUS FAST FLASH SIMULTANEOUS FAST FLASH Normal operation signaled when heating demand initiated at thermostat SLOW FLASH ON Primary or secondary limit switch open Limit must close within 3 minutes or...

Page 11: ...ic or electro mechanical thermostats without modification Each time power is applied to the furnace the ignition con trol performs a selfcheck The SureLight ignitor is made of durable silicon nitride...

Page 12: ...ge to the ignitor until it finds the lowest amount of power that will provide a successful ignition This amount of power is used for 255 cycles On the 256th call for heat the control will again ramp d...

Page 13: ...ge before re moving blower control module cover Failure to wait may cause personal injury or death Remove the cover panel from the module to access the se lector jumpers There are five selector pins i...

Page 14: ...C Ramp A 6 Ignitor The SureLight ignitor is made of durable silicon nitride Ig nitor longevity is enhanced by controlling voltage to the ig nitor The board finds the lowest ignitor temperature which...

Page 15: ...cut out from the side of the cabinet See figure 15 Use the two provided sheet metal screws to install the cut out on the top cap to cover the original flue outlet open ing Combustion Air Inducer Upfl...

Page 16: ...ir blower and closes the gas valve The limit automatically resets when unit temperature returns to normal G50UHi 1 through 6 units use a surface type limit factory set to open at 125 F G50UHi 7 and la...

Page 17: ...eywell Gas Valve Turn knob on gas valve clockwise to OFF Do not force See figure 18 7 Wait five 5 minutes to clear out any gas If you then smell gas STOP Immediately call your gas supplier from a neig...

Page 18: ...n checked and adjusted check manifold pressure Move pressure gauge to outlet pres sure tap located on unit gas valve GV1 Checks of man ifold pressure are made as verification of proper regulator ad ju...

Page 19: ...a tion Current passes from the sensor through the flame to ground to complete a safety circuit TABLE 17 Flame Signal in Microamps Ignition Control Normal Low Drop Out 97L48 0 61 0 21 0 60 0 20 69M15 0...

Page 20: ...onnect the other end of manometer to the return duct as above For systems with non ducted returns leave the other end of the manometer open to the at mosphere 3 With only the blower motor running and...

Page 21: ...aning is accomplished Reverse drill and slowly work the cable out of opening 8 Repeat procedure for each heat exchanger section 9 After each of the top heat exchanger sections has been cleaned insert...

Page 22: ...Page 22 VII WIRING AND SEQUENCE OF OPERATION...

Page 23: ...s into 5 minute Watchguard Pressure Switch delay Once S18 closes a 15 second pre purge follows 4 SureLight control A92 energizes ignitor A 20 second warm up period begins 5 Gas valve opens for a 4 sec...

Page 24: ...WITH DELAY LED 1 OFF LED 2 SLOW FLASH Sequence holds until PROVE switch closes or thermostat resets control NO NO YES NO IS THERE PROPER GROUND IS VOLTAGE ABOVE 75 VOLTS LED 1 AND LED 2 ALTERNATING FA...

Page 25: ...CER OFF INDOOR BLOWER OFF WITH DELAY LED 1 ALT SLOW FLASH LED 2 ALT SLOW FLASH IS 60 MINUTE RESET PERIOD COMPLETE YES 4 SECONDS YES HAS CONTROL RESET IGNITION SEQUENCE FOUR TIMES FLAME SIGNAL NORMAL S...

Page 26: ...TOR AND SYSTEM FAN ENERGIZED AFTER DELAY COOL SPEED AND ELECTRONIC AIR CLEANER TERMINAL IS ENERGIZED Control board 69M15 2 second delay Control board 97L48 no delay COMPRESSOR OFF THERMOSTAT OPENS COO...

Page 27: ...OPENS COMBUSTION AIR INDUCER AND HEATING ACCESSORY TERMINAL ARE DE ENERGIZED INDOOR BLOWER SWITCHES TO COOL SPEED THERMOSTAT OPENS INDOOR BLOWER SWITCHES TO CONTINUOUS BLOWER ELECTRONIC AIR CLEANER T...

Page 28: ...pen ACTION 1 Manually reset the roll out switch by pushing the top button ACTION 2 Determine the cause of the roll out switch activation before leaving furnace code LED 1 O 1 2 2 Roll out switch failu...

Page 29: ...1 Alternating Fast Flash LED 2 Alternating Fast Flash 2 1 2 Broken or failed ignitor ACTION 1 Unplug ignitor and read resistance across ignitor If resistance does not read be tween 10 9 and 19 7 ohms...

Page 30: ...with a heating demand Diagnostic lights flash the pressure switch failure code 2 5 minutes after heating demand 4 1 2 Prove switch does not close due to obstructions in the pressure lines ACTION 1 Re...

Page 31: ...ure switch code LED 1 Off LED 2 Slow Flash 6 1 1 Low pressure differential at the prove switch ACTION 1 Check for restricted exhaust vent Remove all blockage ACTION 2 Check for proper vent sizing See...

Page 32: ...ash 6 3 3 Insufficient flow through the heat exchanger caused by a sooted or restricted heat exchanger ACTION 1 Check for sooting deposits or other restrictions in the heat exchanger assembly Clean as...

Page 33: ...lash 7 1 2 Sense rod is contaminated ACTION 1 Check sense rod for contamination or coated surface Clean the sense rod with steel wool or replace sensor DO NOT USE SAND PA PER TO CLEAN ROD SAND PAPER W...

Page 34: ...t lead from ACB Cool to 120HOT terminal D Make sure blower access panel is replaced properly to close door interlock switch and energize SureLight control board D Repeat with ACB Heat and ACB Low lead...

Page 35: ...ize SureLight control board D Check for proper demand from thermostat Is motor operating properly Recheck all wiring connections CHECK BLOWER CONTROL MODULE Proper blower control module must be instal...

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