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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 –– FAST FLASH
YES
YES
YES
GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.
INDOOR BLOWER DELAY OFF.
LED #1 ON
LED #2 ON
(RESET CONTROL BY TURNING MAIN POWER OFF.)
NO
NO
POLARITY REVERSED.
LED #1 –– FAST FLASH
LED #2 –– SLOW FLASH
NO
POWER ON
COMBUSTION AIR BLOWER ON FOR 1 SECOND.
POLARITY OKAY?
ROLLOUT SWITCH CLOSED?
THERMOSTAT CALLS FOR HEAT:
LED #1 –– FAST FLASH
LED #2 –– FAST FLASH
PRIMARY & SECONDARY LIMIT SWITCHES CLOSED?
PRESSURE SWITCH CONTACTS OPEN?
(HIGH AND LOW FIRE)
TWO–STAGE MODE
CALL FOR 1ST STAGE HEAT
TWO–STAGE MODE
SINGLE STAGE T’STAT
SINGLE–STAGE MODE
HIGH HEAT ONLY
COMBUSTION AIR BLOWER
ON LOW SPEED ( 2.5 MINUTES)
LOW–FIRE PRESSURE
SWITCH CLOSED?
PREPURGE
15 SECONDS
COMBUSTION AIR BLOWER
ON HIGH SPEED ( 2.5 MINUTES)
HIGH–FIRE PRESSURE
SWITCH CLOSED?
GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.
INDOOR BLOWER OFF DELAY.
LED #1 –– ON
LED #2 –– SLOW FLASH
GAS VALVE OFF. COMBUSTION AIR BLOWER ON.
INDOOR BLOWER ON.
LED #1 –– SLOW FLASH
LED #2 –– OFF
GAS VALVE OFF.
COMBUSTION AIR BLOWER OFF.
INDOOR BLOWER OFF DELAY.
LED #1 OFF
LED #2 SLOW FLASH
(Sequence holds until pressure switch
closes or thermostat resets control.)
PRESSURE SWITCH WATCHGUARD
(5 MINUTES)
COMBUSTION AIR BLOWER OFF.
INDOOR BLOWER OFF.
LED #1 OFF
LED #2 SLOW FLASH
NO
NO
COMBUSTION AIR BLOWER OFF.
INDOOR BLOWER ON.
LED #1 –– SLOW FLASH
LED #2 –– ON
NO
NO
WATCHGUARD
60–MINUTE DELAY
YES
YES
NO
YES YES
GAS VALVE OFF. COMBUSTION AIR BLOWER ON.
INDOOR BLOWER ON.
LED# 1 ALTERNATING FAST FLASH
LED# 2 ALTERNATING FAST FLASH
CHECK FOR BROKEN IGNITOR OR OPEN
IGNITOR CIRCUIT
SIGNAL IMPROPER
GROUND AT LED.
SIGNAL HOLDS
UNTIL IS
PROPERLY
GROUNDED.
IS THERE
PROPER GROUND?
IS VOLTAGE
ABOVE 75 VOLTS?
YESNO
LOW VOLTAGE SIGNAL AT LED HOLDS
UNTIL VOLTAGE RISES ABOVE 75 VOLTS
NO
IS COMBUSTION AIR BLOWER ENERGIZED?
(HTG ACC ENERGIZES WITH C.A.B)
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