Gas Manifold Pressure Measurement And Adjustment - Goodman GMH95 Installation Instructions Manual

Open to
Atmosphere
Outlet
Pressure Boss
Inlet
Pressure Boss
On/Off Switch
White-Rodgers Model 36G54 Connected to Manometer
1. Turn OFF gas to furnace at the manual gas shutoff valve
external to the furnace.
2. Connect a calibrated water manometer (or appropriate gas
pressure gauge) at either the gas valve inlet pressure boss
or the gas piping drip leg.
Gas Line
Gas
Shutoff
Valve
Drip Leg Cap
With Fitting
Manometer Hose
Measuring Inlet Gas Pressure (Alt. Method)
NOTE: If measuring gas pressure at the drip leg, a field supplied
hose barb fitting must be installed prior to making the hose
connection. If using the inlet pressure boss on the gas valve,
then use the 36G Valve Pressure Check Kit, Goodman Part No.
0151K00000S.
3. Turn ON the gas supply and operate the furnace and all
other gas consuming appliances on the same gas supply
line.
4. Measure furnace gas supply pressure with burners firing.
Supply pressure must be within the range specified in the
Inlet Gas Supply Pressure table.
Inlet Gas Supply Pressure
Natural Gas
Minimum: 5.0" w.c.
Minimum: 11.0" w.c.
Propane Gas
High Fire Regulator
Adjust Regulator
Vent
Regulator Adjust
High Fire
Coaxial Coil
Coil Terminal (HI)
Terminal (M)
Common
Terminal (C)
Gas Line
To Furnace
Open To
Atmosphere
Manometer
Maximum:10.0" w.c.
Maximum:13.0" w.c.
If supply pressure differs from table, make the necessary adjust-
ments to pressure regulator, gas piping size, etc., and/or consult
with local gas utility.
5. Turn OFF gas to furnace at the manual shutoff valve and
disconnect manometer. Reinstall plug before turning on
gas to furnace.
6. Turn OFF any unnecessary gas appliances started in step
3.
G M
AS ANIFOLD
Low Fire
T
O PREVENT UNRELIABLE OPERATION OR EQUIPMENT DAMAGE, THE GAS
MANIFOLD PRESSURE MUST BE AS SPECIFIED ON THE UNIT RATING PLATE.
O
NLY MINOR ADJUSTMENTS SHOULD BE MADE BY ADJUSTING THE GAS VALVE
PRESSURE REGULATOR.
Only small variations in gas pressure should be made by adjust-
ing the gas valve pressure regulator. The manifold pressure must
be measured with the burners operating. To measure and adjust
the manifold pressure, use the following procedure.
1. Turn OFF gas to furnace at the manual gas shutoff valve
external to the furnace.
2. Turn off all electrical power to the system.
3. Back outlet pressure test screw (inlet/outlet pressure boss)
out one turn (counterclockwise, not more than one turn).
4. Attach a hose and manometer to the outlet pressure boss
of the valve.
5. Turn ON the gas supply.
6. Turn on power and energize main (M) solenoid. Do not
energize the (HI) solenoid.
7. Measure gas manifold pressure with burners firing. Adjust
manifold pressure using the Manifold Gas Pressure table
shown below.
8. Remove regulator cover screw from the low (LO) outlet
pressure regulator adjust tower and turn screw clockwise
to increase pressure, or counterclockwise to decrease
pressure.
9. Energize main (M) solenoid as well as the (HI) terminal.
10. Remove regulator cover screw from the (HI) outlet pressure
regulator adjust tower and turn screw clockwise to increase
pressure, or counterclockwise to decrease pressure.
11. Turn off all electrical power and gas supply to the system.
12. Remove manometer hose from outlet pressure boss.
13. Turn outlet pressure test screw in to seal pressure port
(clockwise, 7 in-lb minimum).
14. Turn on electrical power and gas supply to the system.
15. Turn on system power and energize valve.
16. Using a leak detection solution or soap suds, check for
leaks at pressure boss screw. Bubbles forming indicate a
leak. SHUT OFF GAS AND FIX ALL LEAKS IMMEDIATELY.
NOTE: For gas to gas conversion, consult your dealer for
appropriate conversion.
28
P M
RESSURE EASUREMENT AND
CAUTION
A
DJUSTMENT