Lennox G61MPV Service Manual page 80

CONTINUED
IS PRIMARY, SECONDARY, BACKUP
SECONDARY LIMIT AND ROLLOUT
SWITCH CLOSED?
YES
FIRST−STAGE (LOW FIRE) HEAT
PRESSURE SWITCH CLOSED?
SECOND−STAGE (HIGH FIRE) HEAT
PRESSURE SWITCH CLOSED?
YES
HEAT DEMAND SATISFIED?
DS1 AND DS2 SIMULTANEOUS FAST FLASH.
YES
SINGLE−STAGE THERMOSTAT MODE
(E20 SET AT SINGLE")
YES
HEAT DEMAND SATISFIED?
DS1 AND DS2
SIMULTANEOUS FAST FLASH.
YES
GAS VALVE OFF, COMBUSTION AIR
INDUCER OFF AFTER 5−SECOND
LOW SPEED POST PURGE PERIOD,
INDOOR BLOWER OFF DELAY
INITIATED ON LOW HEAT SPEED.
DS1 AND DS2
SIMULTANEOUS FAST FLASH
DEMAND FOR HEAT SATISFIED.
POWER ON STAND BY.
DS1 AND DS2
SIMULTANEOUS SLOW FLASH
HEATING SEQUENCE OF OPERATION
DS 1 AND DS 2 SIMULTANEOUS FAST FLASH
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
NO
HAS PRIMARY, SECONDARY, BACKUP SECONDARY
OR ROLLOUT SWITCH CLOSED WITHIN 3 MINUTES?
GAS VALVE OFF, COMBUSTION AIR INDUCER OFF
NO
NO
YES
TWO STAGE THERMOSTAT MODE?
(E20 SET AT TWO")
YES
FIRST AND SECOND STAGE HEAT
DEMAND SATISFIED SIMULTANEOUSLY.
DS1 & DS2 SIMULTANEOUS FAST FLASH.
YES
Page 80
SEE BOX A
NORMAL OPERATION
DS1 AND DS2 SIMULTANEOUS SLOW FLASH.
SEE BOX B
THERMOSTAT CALLS FOR HEAT
INDOOR BLOWER ON.
DS1 SLOW FLASH, DS2 ON,
ON/OFF LED ON, HEAT LED 0N.
NO
LIMIT SWITCH WATCHGUARD MODE. GAS VALVE
OFF. COMBUSTION AIR INDUCER OFF. INDOOR
BLOWER OFF WITH DELAY. IS 60−MINUTE RESET
PERIOD COMPLETE? DS SLOW FLASH, DS2 ON,
ON/OFF LED OFF, HEAT LED OFF.
AFTER 15 SECOND POST PURGE, INDOOR
BLOWER OFF AFTER DELAY.
DS1 OFF, DS2 FAST FLASH,
ON/OFF LED ON, HEAT LED ON.
RETURN TO HEAT DEMAND?
RETURN TO FIRST−STAGE HEAT MODE.
FIRST−STAGE CONTINUES UNTIL SECOND−
STAGE PRESSURE SWITCH CAN BE PROVEN
or HEAT DEMAND IS SATISFIED. A FIVE (5)
MINUTE WAIT PERIOD IS INITIATED BEFORE
RETRY. WERE 5 ATTEMPTS MADE FOR
SECOND−STAGE HEAT?
NO
SEE BOX C
FIRST−STAGE HEAT DEMAND SATISFIED?
NO
SIMULTANEOUS FAST FLASH.
GAS VALVE, COMBUSTION AIR INDUCER
AND INDOOR BLOWER RETURN TO FIRST−
STAGE OPERATION.
DS1 AND DS2 SIMULTANEOUS FAST FLASH.
FIRST STAGE HEAT DEMAND SATISFIED?
GAS VALVE OFF. COMBUSTION AIR INDUCER
OFF AFTER 5−SECOND LOW SPEED POST−
PURGE PERIOD. INDOOR BLOWER OFF.
DELAY INITIATED ON LOW HEAT SPEED.
DS1 & DS2 SIMULTANEOUS FAST FLASH.
YES
YES
YES
YES
SECOND STAGE HEAT
DEMAND SASTISFIED?
DS1 AND DS2
YES
YES