7. Turn on furnace power supply.
WARNING: FIRE, EXPLOSION, INJURY OR DEATH HAZARD
Failure to follow this warning could result in fire, explosion, personal injury, or death.
NEVER use matches, candles, flame, or other sources of ignition to check for gas leakage. Use a soap-and-water solution to check
for gas leaks.
PROCEDURE 10—SET GAS INPUT RATE INFORMATION
The gas input rate for propane is the same as for natural gas. See furnace rating plate (See Fig. 25.) for input rate. The input rate for propane is
determined by manifold pressure and orifice size. The gas-valve regulator must be set for low heat first and then set for high heat on 2-Stage and
Variable Speed furnaces. The gas valve regulator must also be adjusted on Single Stage furnaces.
NOTE:
Manifold pressure must always be measured with the burner enclosure front removed. (See Fig. 27.) Furnace gas input rate on rating plate
is for installations at altitudes up to 2000 ft.
In the U.S.A., the input rating for altitudes above 2000 ft must be reduced by 2 percent for each 1000 ft above sea level.
In Canada, the input rating must be derated by 5 percent for altitudes of 2000 ft to 4500 ft above sea level.
The Conversion Kit Rating Plate accounts for high altitude derate.
A.
Set Gas Input Rate on Single Stage Furnaces
1. Jumper R and W thermostat connections to call for heat. (See Fig. 8A or 8B.)
2. Check manifold orifices for gas leaks when main burners ignite.
3. Adjust gas manifold pressure.
a. Remove burner box cover (See Fig. 27) and gas valve regulator seal cap that conceal adjustment screw. (See Fig. 22A or 22B.)
NOTE:
Manifold pressure MUST always be measured with burner box cover removed.
b. Turn adjusting screw counterclockwise (out) to decrease manifold pressure or clockwise (in) to increase manifold pressure.
NOTE:
Gas valve regulator seal cap MUST be in place when checking input rate.
c. When correct input is obtained, main burner flame should be clear blue, almost transparent. (See Fig. 28.) Be sure regulator seal cap is
in place when finished.
4. Remove jumper across R and W thermostat connections to terminate call for heat.
5. Turn furnace gas valve control switch or control knob to OFF position.
6. Turn off furnace power supply.
7. Remove manometer and replace manifold pressure tap plug. (See Fig. 22A, 22B, 22C, or 22D.)
NOTE:
Use propane-gas-resistant pipe dope to prevent gas leaks. DO NOT use Teflon tape.
8. Reinstall burner box cover.
9. Turn furnace gas valve control switch or control knob to ON position.
10. Turn on furnace power supply.
11. Set room thermostat to call for heat.
12. Check manifold pressure tap plug for gas leaks when main burners ignite.
Fig. 24—Adjusting Manifold Pressure (Manifold Attachment)
A01070
7
6
5
4
3
2
1
0
1
2
3
4
5
6
7
BURNER ENCLOSURE
(REMOVE COVER WHEN
CHECKING PRESSURE)
GAS VALVE
PRESSURE
SWITCH(ES)
(LOCATION WILL VARY
DEPENDING ON MODEL)
MANOMETER
—26—
