Heating Sequence - Lennox G40UH Series Installation Instructions Manual

HEATING SEQUENCE CONTINUED
NORMAL HEATING MODE ABNORMAL HEATING MODE
15-SECOND COMBUSTION AIR INDUCER PREPURGFI9
INITIATED BY CLOSED PRESSURE SWITCH. I
YES
NO
I IGNITER WARM-UP -- 20 SECONDS. I'_1
YES
4-SECOND TRIAL FOR IGNITION.
GAS VALVE OPENS. IGNITER ENERGIZED FOR
UP TO 4 SECONDS.
,4
I
I
I
YES
FLAME STABILIZATION PERIOD.
4 SECONDS
_
FLAME RECTIFICATION CURRENT
CHECK. CAN FLAME BE PROVEN WITHIN
4 SECONDS AFTER GAS VALVE OPENS?
(0.5 microamps)
YES _
FLAME PRESENT?
YES
1
FLAME SIGNAL 1.5 MICROAMPS OR GREATER?
YES _
INDOOR BLOWER ON
AFTER 45-SECOND DELAY
YES _1
PRIMARY AND SECONDARY LIMIT
SWITCHES CLOSED?
YES
I ROLLOUT SWITCH CLOSED?
YES
_'I COMBUSTION AIR PRESSURE
SWITCH CLOSED?
YES
I THERMOSTAT DEMAND SATISFIED.
YES
I LED #1 & #2 SIMULTANEOUS SLOW FLASHES.
YES
COMB. AIR INDUCER CONTINUES 5-SECOND
POST PURGE AFTER T'STAT DEMAND IS SATISFIED.
INDOOR AIR BLOWER COMPLETES SELECTED
[ OFF DELAY BEFORE SHUTT NG OFF.
IS VOLTAGE ABOVE 90 VOLTS?
YES
LEDS SIGNAL
ALTERNATING
FAST FLASH UNTIL
VOLTAGE IS ABOVE
95 VOLTS, THEN
RESTARTS HEATING
SEQUENCE.
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
INDOOR BLOWER OFF. I NO
HAS CONTROL FAILED TO SENSE FLAME FOR
I HEAT DEMAND?
F VE CONSECUT VE TR ES DUR NG A S NGLE
_t ES
I__ WATCHGUARD MODE. GAS VALVE OFF. I_
COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH DELAY
LEDs SIGNAL WATCHGUARD FAILURE CODE.
IS 60-MINUTE RESET PERIOD COMPLETE?
_t HAS CONTROL RESET IGNITION pI NO
SEQUENCE FOUR TIMES?
YES
I
LOW FLAME SIGNAL LIMIT SWITCH WATCHGUARD
(Does not affect operation of control) MODE. GAS VALVE, COMB. AIR
LED #1 -- SLOW FLASH INDUCER AND INDOOR BLOW-
LED #2 -- FAST FLASH
ER OFF. LEDs SIGNAL LIMIT
SWITCH OPEN UNTIL MAIN
POWER IS
I GAS VALVE DE-ENERGIZED. INTERRUPTED OR
I COMBUSTION AIR INDUCER DE-ENERGIZED. I T'STAT IS CYCLED
I NO I INDOOR BLOWER ON UNTIL SWITCH CLOSES. I OFF/ON FOR 1
LED #1 -- SLOW FLASH. LED #2 -- ON. I SEC. MINIMUM.
I I IS LIMIT SWITCH CLOSED? I 60-MINUTE WATCH-
GUARD PERIOD YES STARTS AT TIME
I HAS PRIMARY / SECONDARY IYES LIMIT CLOSES.
LIMIT RESET TIME _ IS 60-MIN PERIOD
EXCEEDED 3 MINUTES? COMPLETE?
• I NO
NO GAS VALVE POWER OFF.
COMBUSTION AIR INDUCER POWER ON.
INDOOR BLOWER ON
LED #1 -- ON. LED #2 -- SLOW FLASH.
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH IS RESET
AND MAIN POWER IS INTERRUPTED OR
__'_NI_.._, THERMOSTAT IS CYCLED OFF/ON FOR 1 SEC. MINIMUM.
I i
GAS VALVE DE-ENERGIZED.
COMBUSTION AIR INDUCER ON. YES
I INDOOR BLOWER OFF WITH DELAY
LED #1 -- OFF. LED #2 -- SLOW FLASH.
I I HASCAB SWITCH CLOSED IN2.5MINUTES? I
I
NO
I 5"M'NUTE PRESSURE SW'TCHI
WATCHGUARD MODE.
b
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