MODEL F80A
START UP PROCEDURES
This furnace is equipped with a hot surface ignition (HSI) device. Each time that the room thermostat calls for heat, the HSI lights the main burners directly. See the lighting instructions on the furnace.
TO START THE FURNACE:
1.Remove the burner compartment access door.
2.Shut off the electrical power to the furnace and set the room thermostat to its lowest setting.
3.Ensure that the ignition system control switch on the White- Rodgers 36G22 gas valve is in the “ON” position.
4.Replace the burner compartment access door.
5.Restore electrical power to the furnace.
6.Set the room thermostat to a point above room temperature to light the furnace.
7.After the burners are lit, set the room thermostat to the desired temperature.
TO SHUT DOWN THE FURNACE:
1.Set the room thermostat to its lowest setting.
2.Remove the burner compartment access door.
3.The ignition system control switch on the
4.The furnace appliance shutoff valve may be closed if desired.
WARNING
SHOULD OVER HEATING OCCUR, OR THE GAS BURNERS FAIL TO SHUT OFF, CLOSE THE MANUAL GAS VALVE FOR THE FURNACE BEFORE SHUTTING OFF THE ELECTRICAL POWER TO THE FURNACE. FAILURE TO DO SO CAN CAUSE AN EXPLOSION OR FIRE RESULTING IN PROPERTY DAMAGE, PERSONAL INJURY OR LOSS OF LIFE.
SEQUENCE OF OPERATION
1.Room temperature drops causing the room thermostat heating contacts to close.
2.The induced blower begins a prepurge cycle of 15 seconds.
3.The pressure switch contacts close.
4.After the prepurge period, the hot surface igniter heats up; 10 seconds on a first try, maximum 14 seconds on a subsequent retry.
5.The gas valve opens for a 7 second trial for ignition. The gas burners light, the igniter shuts off. (See next section for sequence of operation in the event of a flame failure).
6.The circulating fan begins 30 seconds after flame is sensed.
7.Furnace continues to run in this state until the room thermostat heating contacts open in response to raised room temperature.
8.With the thermostat heating contacts open, the burner flames extinguish immediately, the induced blower stops after a 5 second postpurge period. The pressure switch contacts open.
9.The circulating fan continues to run until timed out in 60 to 180 seconds, depending on the
Sequence if the furnace does not light up or detect flame:
1.See steps 1 through 5 for initial operation.
2.If pressure switch contacts are closed; and have failed to open since the last cycle, all subsequent steps will fail to occur.
3.If the burners fail to light, or if the flame is not sensed, the gas valve closes, and, providing that there have been less than 5 trials for ignition, sequence returns to sequence of operation Step 4. If this was the 5th trial for ignition, the ignition system goes into a 60 minute lockout condition, and then reattempts the sequence at Step 4.
In addition, if during the burner firing, the flame signal is lost, the gas valve will close and the ignition sequence will begin again at Step 4 above. If the flame sensing signal is lost more than 5 times during a furnace cycle, the gas valve will close, and the ignition sequence goes into a 5 second postpurge; the induced blower stops. The ignition system goes into a 60 minute lockout condition then reattempts the sequence at Step 4 above.
The 60 minute lockout sequence will repeat itself indefinitely. Lowering the room thermostat setting below room temperature for approximately 10 seconds, or shutting off the electrical supply to the furnace for approximately 10 seconds may interrupt the 60 minute lockout.
4.Furnace continues to run in this state until the room thermostat heating contacts open in response to raised room temperature.
5.With the thermostat heating contacts open, the burner flames extinguish immediately, the induced blower stops after a 5 second postpurge period. Pressure switch contacts open.
6.The circulating fan continues to run until timed out in 60 to 180 seconds, depending on the
Additional information is available in the Troubleshooting section that starts on page 22 of this manual.
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