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X- Troubleshooting
Troubleshooting: Heating Sequence of Operation
CALL FOR FIRST-STAGE HEAT
1
CALL FOR
1ST STAGE HEAT
(LOW FIRE)
HIGH
LIMIT SWITCH
CLOSED?
YES
ROLLOUT
CIRCUITS
CLOSED?
YES
LOW
PRESSURE
SWITCH
OPEN?
YES
INDUCER ON
LOW SPEED
LOW
PRESSURE SWITCH
CLOSED WITHIN 120
SECONDS?
YES
PRE−PURGE
(15 SECONDS)
H.S.I. ON
(20 SECONDS)
1ST STAGE GAS
3
VALVE ENERGIZED
IGNITION TRIAL
HEAT FAN ON DELAY
BEGINS (H.S.I. ON)
TIMER STARTED
FLAME
SENSED WITHIN
4 SECONDS?
YES
H.S.I. OFF
INDOOR
BLOWER ON 30 SEC.
(LOW HEAT SPEED)
2
CALL FOR HEAT SATISFIED
INDOOR BLOWER OFF AFTER
YES
HEAT FAN OFF DELAY
(LOW HEAT SPEED)
ERROR
INDOOR
NO
CODE
BLOWER
FLASHES
ON(LOW HEAT
SPEED)
INDUCER ON
(HIGH SPEED)
DE−ENERGIZE
NO
GAS VALVE
INDOOR BLOWER
ON (LOW HEAT
SPEED)
ERROR CODE
FLASHES (AFTER
NO
5 SECONDS)
LOW PRESSURE
SWITCH OPENS
HIGH
PRESSURE
SWITCH
OPEN
NO
BEFORE
INDUCER WAS
TURNED ON?
YES
INTERPURGE
(15 SECONDS)
NO
GAS VALVE
DE−ENERGIZED
5TH
NO
UNSUCCESSFUL
TRIAL?
H.S.I. OFF
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.
NO
INDOOR
LIMIT
BLOWER OFF
SWITCH
AFTER HEAT FAN
NO
CLOSED WITHIN 3
OFF DELAY (LOW
MINUTES?
HEAT SPEED)
ROLLOUT
CIRCUIT
ERROR
CLOSES
CODE
(MANUAL
FLASHES
RE−SET)
NO
INDUCER OFF
AFTER POST
PURGE
INDOOR BLOWER
OFF AFTER HEAT
OFF DELAY
HARD LOCKOUT −
ERROR CODE
FLASHES
LOW & HIGH
INDUCER TO
PRESSURE SWITCH
HIGH SPEED−
CLOSED WITHIN 30
ERROR CODE
SECONDS?
FLASHES
YES
NO
POSTPURGE
INDUCER
YES
(5 SECONDS)
OFF
Page 92
WATCHGUARD −
ERROR CODE
1
FLASHES
NO
CALL
FOR HEAT
ENDS?
YES
YES
2
NO
INDOOR
INDOOR
BLOWER
BLOWER
YES
ON?
ON?
YES
INDUCER OFF−
INDOOR
WAIT
BLOWER
5 MINUTES
OFF AFTER
ERROR CODE
HEAT FAN
FLASHES
OFF DELAY
1
WATCHGUARD −
ERROR CODE
1
FLASHES
NO
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