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HEATING SEQUENCE OF OPERATION WITH SINGLE-STAGE THERMOSTAT CONTINUED

NORMAL HEATING MODE

IS THE S10 (S99) HIGH LIMIT CLOSED?

YES

IS W1 DEMAND OF

THERMOSTAT SATISFIED?

YES

A3 (A12) LED OFF

SECOND-STAGE OF GV1 (GV3)

GAS VALVE CLOSES AFTER APRROXIMATELY 3 SEC. AND THEN FIRST-STAGE CLOSES.

B6 (B15) COMBUSTION

AIR BLOWER OFF.

B3 SYSTEM BLOWERS OFF

AFTER 150 SEC DELAY.

NO

ABNORMAL HEATING MODE

DETERMINE WHY AUTOMATIC-RESET S10 (S99) HIGH LIMIT OPEN. K20, (K123), K36

RELAYS MAINTAIN BLOWER OPERATION.

NOTE − IF ECONOMIZER INSTALLED, ECONOMIZER OPERATES WHEN BLOWER POWERED.

LED CODES

1 − ON NORMAL OPERATION WITH THERMOSTAT CALLING FOR HEAT. 2 − 0.5 SEC ON AND 2.5 SECS OFF IN IGNITION RETRY PERIOD.

3 − OFF NO POWER OR DETECTED FAULT.

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Lennox International Inc G24-200 installation instructions IS THE S10 S99 HIGH LIMIT CLOSED? YES