64
Rev. 0
SERVICING
6. After check and/or replacement of orifice(s) reinstall
manifold to burner bracket.
7. Turn on gas to furnace and check for leaks. If leaks are
found, repair and then reinstall burner compartment
door.
8. Turn on electrical power and verify proper unit opera-
tion.
S-12 CHECKING GAS PRESSURE
Gas Supply Pressure Measurement
CAUTION
To prevent unreliable operation or equipment damage,
the inlet gas supply pressure must be as specified on
the unit rating plate with all other household gas fired
appliances operating.
Gas inlet and manifold pressures should be checked and
adjusted in accordance to the type of fuel being consumed.
The line pressure supplied to the gas valve must be within
the range specified below. The supply pressure can be
measured at the gas valve inlet pressure tap or at a hose
fitting installed in the gas piping drip leg. The supply pres-
sure must be measured with the burners operating. To
measure the gas supply pressure, use the following proce-
dure.
WARNING
Disconnect Electrical Power and Shut Off Gas Supply:
1. After turning off gas to furnace at the manual gas shutoff
valve external to the furnace, remove burner compart-
ment door to gain access to the gas valve.
3. Connect a calibrated water manometer (or appropriate
gas pressure gauge) at either the gas valve inlet pres-
sure tap or the gas piping drip leg as shown in the fol-
lowing two figures.
Note: At either location, a hose fitting must be installed
prior to making the hose.connection.
Manometer Hose
O
F
F
ON
M
P
C
1
3
2
WR
INLET
OUTLET
Pressure Regulator Adjustment
(Under Cap Screw)
Inlet Pressure Tap
(Side of Valve)
Outlet (Manifold)Pressure Tap
(Side of Valve)
Gas Valve Control
ON/Off Switch
Manometer
Open to
Atmosphere
Measuring Inlet Gas Pressure
(Gas Valve Tap)
Gas Line
Gas Shutoff Valve
Gas Line
To Furnace
Drip Leg Cap
With Fitting
Manometer Hose
Manometer
Open To
Atmospere
Measuring Inlet Gas Pressure
(Alternate Method)
4. Turn ON the gas and electrical power supply and oper-
ate the furnace and all other gas consuming appliances
on the same gas supply line.
5. Measure furnace gas supply pressure with burners fir-
ing. Supply pressure must be within the range specified
in the table below.
Inlet Gas Supply Pressure
Natural Gas
Minimum:5.0" W.C. Maximum :10.0" W.C.
Propane Gas
Minimum:11.0" W.C. Maximum :13.0" W.C.
If supply pressure differs from above, make necessary ad-
justments to pressure regulator, gas piping size, etc., and/
or consult with local gas utility.
WARNING
Disconnect Electrical Power and Shut Off Gas Supply:
6. Disconnect manometer after turning off gas at manual
shutoff valve. Reinstall plug before turning on gas to
furnace.
7. Turn OFF any unnecessary gas appliances started in
step 3.
8. Turn on gas to furnace and check for leaks. If leaks are
found, repair and then reinstall burner compartment
door.
9. Turn on electrical power and verify proper unit opera-
tion.