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X- Troubleshooting
Heating Sequence of Operation
CALL FOR FIRST-STAGE HEAT
CALL FOR
1ST STAGE HEAT
(LOW FIRE)
LIMIT SWITCH
CLOSED?
ROLLOUT
CIRCUITS
CLOSED?
PRESSURE
SWITCH
OPEN?
INDUCER ON
LOW SPEED
PRESSURE SWITCH
CLOSED WITHIN 120
SECONDS?
PRE−PURGE
(15 SECONDS)
H.S.I. ON
(20 SECONDS)
1ST STAGE GAS
VALVE ENERGIZED
IGNITION TRIAL
BEGINS (H.S.I. ON)
SENSED WITHIN
4 SECONDS?
H.S.I. OFF
INDOOR
BLOWER ON 30 SEC.
(LOW HEAT SPEED)
CALL FOR HEAT SATISFIED
1
INDOOR BLOWER OFF AFTER
HEAT FAN OFF DELAY
(LOW HEAT SPEED)
HIGH
ERROR
INDOOR
NO
CODE
BLOWER
FLASHES
ON(LOW HEAT
YES
DE−ENERGIZE
NO
GAS VALVE
YES
LOW
ERROR CODE
FLASHES (AFTER
NO
5 SECONDS)
LOW PRESSURE
SWITCH OPENS
YES
HIGH
PRESSURE
LOW
SWITCH
OPEN
NO
BEFORE
INDUCER WAS
TURNED ON?
YES
3
HEAT FAN ON DELAY
TIMER STARTED
GAS VALVE
FLAME
DE−ENERGIZED
NO
H.S.I. OFF
YES
1
WATCHGUARD LOCKOUT AUTOMATICALLY RESETS AFTER ONE HOUR
2 HARD LOCKOUT REQUIRES THERMOSTAT RESET OR CYCLING OF POWER TO RESET THE LOCKOUT.
3 IN CASE HIGH SPEED INDUCER IS RUNNING AT THE TIME THE GAS VALVE GETS ENERGIZED,
2ND STAGE GAS VALVE IS ENERGIZED INSTEAD OF 1ST STAGE. 20 SECONDS AFTER FLAME
IS SENSED, INDUCER SWITCHES TO LOW SPEED, AND GAS VALVE SWITCHES TO 1ST STAGE.
2
NO
YES
LIMIT
SWITCH
NO
CLOSED WITHIN 3
MINUTES?
SPEED)
INDUCER ON
(HIGH SPEED)
ERROR
CODE
FLASHES
INDOOR BLOWER
ON (LOW HEAT
SPEED)
NO
INDUCER TO
HIGH SPEED−
YES
ERROR CODE
FLASHES
INTERPURGE
(15 SECONDS)
NO
5TH
POSTPURGE
UNSUCCESSFUL
YES
(5 SECONDS)
TRIAL?
Page 74
INDOOR
BLOWER OFF
WATCHGUARD −
AFTER HEAT FAN
ERROR CODE
OFF DELAY (LOW
FLASHES
HEAT SPEED)
ROLLOUT
CIRCUIT
CLOSES
YES
INDUCER OFF
AFTER POST
PURGE
INDOOR BLOWER
OFF AFTER HEAT
OFF DELAY
HARD LOCKOUT −
ERROR CODE
2
FLASHES
LOW & HIGH
PRESSURE SWITCH
NO
CLOSED WITHIN 30
SECONDS?
YES
YES
INDUCER OFF−
NO
WAIT
5 MINUTES
ERROR CODE
FLASHES
WATCHGUARD −
INDUCER
ERROR CODE
OFF
FLASHES
1
NO
CALL
FOR HEAT
ENDS?
YES
INDOOR
INDOOR
BLOWER
BLOWER
ON?
ON?
NO
YES
INDOOR
BLOWER
OFF AFTER
HEAT FAN
OFF DELAY
1
1
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