Lennox DAVE SIGNATURE SL280DFV Installation Instructions Manual page 52

CALL FOR FIRST-STAGE HEAT
1
CALL FOR
1ST STAGE HEAT
(LOW FIRE)
INDOOR BLOWER OFF AFTER
HEAT FAN OFF DELAY
HIGH
LIMIT SWITCH
NO
CLOSED?
YES
ROLLOUT
CIRCUITS NO
CLOSED?
YES
LOW
PRESSURE
NO
SWITCH
OPEN?
YES
INDUCER ON
LOW SPEED
LOW
PRESSURE SWITCH
NO
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
NO
4 SECONDS?
YES
H.S.I. OFF
INDOOR
BLOWER ON 30 SEC.
(LOW HEAT SPEED)
2
CALL FOR HEAT SATISFIED
YES
(LOW HEAT SPEED)
ERROR
INDOOR
CODE
BLOWER CLOSED WITHIN 3
FLASHES
ON(LOW HEAT
SPEED)
INDUCER ON
(HIGH SPEED)
DE−ENERGIZE
GAS VALVE
INDOOR BLOWER
ON (LOW HEAT
SPEED)
ERROR CODE
FLASHES (AFTER
5 SECONDS)
LOW PRESSURE
SWITCH OPENS
HIGH
PRESSURE
SWITCH
OPEN
BEFORE
INDUCER WAS
INDUCER TO
TURNED ON?
HIGH SPEED−
YES
ERROR CODE
INTERPURGE
(15 SECONDS)
NO
GAS VALVE
DE−ENERGIZED
5TH
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.
Page 52
NO
INDOOR
LIMIT
BLOWER OFF
SWITCH
AFTER HEAT FAN
NO
OFF DELAY (LOW
MINUTES?
HEAT SPEED)
ROLLOUT
ERROR
CIRCUIT
CODE
FLASHES
CLOSES
NO
INDUCER OFF
AFTER POST
PURGE
INDOOR BLOWER
OFF AFTER HEAT
OFF DELAY
HARD LOCKOUT −
ERROR CODE
FLASHES
LOW & HIGH
PRESSURE SWITCH
CLOSED WITHIN 30
SECONDS?
FLASHES
YES
INDUCER OFF−
NO
5 MINUTES
ERROR CODE
POSTPURGE
INDUCER
YES
(5 SECONDS)
OFF
WATCHGUARD −
ERROR CODE
1
FLASHES
NO
CALL
FOR HEAT
ENDS?
YES
YES
2
NO
INDOOR INDOOR
BLOWER BLOWER
YES
ON? ON?
NO
YES
INDOOR
WAIT
BLOWER
OFF AFTER
HEAT FAN
FLASHES
OFF DELAY
1
WATCHGUARD −
ERROR CODE
1
FLASHES