5
9. If no gas odor is detected after 5 minutes, move or rotate the
furnace’s gas control valve On/Off switch to the ON position.
NOTE: The switch should turn easily. Do not use excessive
force.
10. Reinstall the burner compartment door.
11. Open the external manual gas shutoff valve.
12. Turn on the electrical power to the unit.
13. Adjust the thermostat to a setting above room temperature.
14. After the burners are lit, set the thermostat to the desired
temperature.
Heating Shutdown
To shut down operation, follow the steps listed below.
1. Set the thermostat to the lowest setting.
2. Turn OFF electrical power to the unit.
3. Remove the heat exchanger door on the side of the unit by
removing the screws.
4. Move the gas control switch to the OFF position.
NOTE: Do not use excessive force.
5. Close the external manual gas shutoff valve.
6. Reinstall the heat exchanger door.
7. If cooling and/or air circulation is desired, turn ON the
electrical power.
Cooling Operation
Cooling operation may be obtained as follows:
1. Place the room thermostat selector switch in the COOL
position (or AUTO, if available, and if automatic changeover
from cooling to heating is desired).
2. Set the room thermostat to the desired temperature.
3. If the cooling system does not energize, wait 5 minutes. The
system start-up may be delayed by the short-cycle protector
feature of the ignition control board. Check the manual reset
devices on the rollout limit switch, as described in this
manual.
Gas Control Valve—White-Rodgers 36G22
Gas Control Valve—Honeywell Model VR8215—Single
Stage
SAFETY CIRCUITS
A number of safety circuits are employed to ensure safe and
proper unit operation. These circuits serve to control any
potential safety hazards and, provide inputs in the monitoring and
diagnosis of abnormal operation.
Secondary Limit Control
The secondary limit control is located on the blower housing and
monitors blower compartment temperatures. It is a normally-
closed (electrically), automatic-reset, temperature-activated
sensor. This limit guards against overheating as a result of
insufficient conditioned air passing over the heat exchanger. It
de-energizes the gas control valve if the blower fails.
NOTE: If the power to the unit is interrupted during the heating
cycle, it may cause the secondary limit control to trip. Once the
blower compartment temperature drops below the limit reset
temperature, the limit will automatically reset.
Secondary Limit Control
A. Inlet
B. On/Off selector switch
C. Outlet
A
C
B
A. Inlet
B. On/Off selector switch
C. Outlet
A. Secondary limit control
B. Back of unit
A
B
C
If the secondary limit control should open, the reason
must be determined before the control resets. The
electrical power must be disconnected before any panel
is removed or maintenance is performed.
WARNING
A
B
