7. Remove the inlet pressure tap plug on the gas control valve
and connect pressure gauge to the ¹⁄₈" NPT inlet
8. Turn on the gas supply at the manual gas shutoff valve.
9. Observe the inlet pressure.
The minimum inlet gas supply pressure is 5" W.C. for Natural
gas and 11" W.C. for propane gas.
The maximum inlet gas supply pressure is 10.5" W.C. for
Natural gas and 13" W.C. for propane gas.
10. Turn off the gas supply at the manual gas shutoff valve.
IMPORTANT: If the inlet gas supply pressure is not within the
minimum and maximum range as shown on the rating plate,
contact your gas supplier.
11. Disconnect the pressure gauge from the ¹⁄₈" NPT inlet
12. Replace the inlet pressure tap plug on the gas control valve.
13. Turn on the gas supply at the manual gas shutoff valve.
14. Test all connections by brushing on an approved
noncorrosive leak-detection solution. Bubbles will show a
leak. Correct any leak found.
At test pressures greater than ¹⁄₂ psig (3.5 kPa), the
furnace and the manual gas shutoff valve must be
disconnected from the gas supply piping system.
At test pressures less than or equal to ¹⁄₂ psig (3.5 kPa),
the furnace must be isolated from the gas supply piping
system by closing the manual gas shutoff valve.
15. Replace the burner access door.
Check the Furnace Input Rate
The furnace input rate must not exceed the input rating on
the furnace rating plate.
At altitudes from 4,500 to 7,500 ft the furnace input rate must
not exceed that on the rating plate multiplied by the Input
Factor in the Manifold Pressure vs. Altitude Chart in the
"Adjust the Furnace Input Rate" section.
This furnace is equipped for rated input at manifold pressures
of 1.7" W.C. (1st stage) and 3.5" W.C. (2nd stage) for Natural
gas. When an LP conversion kit is used, it is equipped for
rated input at manifold pressures of 4.9" W.C. (1st stage) and
10.0" W.C. (2nd stage) for propane gas.
For Natural gas, check the furnace rate by observing the gas
meter, making sure all other gas appliances are turned off.
The test hand on the meter should be timed for at least one
Cu. ft per Revolution
# Seconds per Revolution
NOTE: The actual heating value of your gas can be obtained from
your local utility company.
1. Remove the burner access door.
2. Turn the gas control switch to the OFF position. Use only your
3. Remove the outlet pressure tap plug on the gas control valve
Gas Control Valve
4. Be sure the gas control switch has been in the OFF position
5. Move the gas control switch to the ON position.
6. Turn on the electrical power to the furnace.
7. Set the room thermostat to a point above room temperature
8. Observe the pressure reading on the pressure gauge.
9. Refer to the Manifold Pressure vs. Altitude Chart later in this
x 3600 x Heating
Adjust the Furnace Input Rate
For Altitudes 4,500 to 7,500 ft Above Sea Level
hand to move the gas control switch; tools are not required.
and connect pressure gauge to the ¹⁄₈" NPT outlet
A. Regulator adjusting cap—LO
" NPT outlet
" NPT outlet pressure tap
for at least 5 minutes before starting the unit.
NOTE: This furnace is equipped with an ignition device which
automatically lights the burner. This furnace cannot be lighted
manually. Do not try to light the burner by hand.
to light the main burners.
section for the correct manifold pressure. If necessary, turn
the regulator adjusting screw clockwise to increase pressure
and input, or counterclockwise to decrease pressure and
input. The gas control valve has 2 separate adjusting screws
for first-stage marked "LO" and the second-stage marked
NOTE: The pressure regulator adjustment is sensitive; one
turn of the adjusting screw will result in a large change in
IMPORTANT: If the manifold pressure cannot be adjusted to
the correct value, contact your gas supplier.
D. Gas control switch
" NPT inlet
" NPT inlet pressure tap (IN P)
G. Regulator adjusting cap—HI