Checking Gas Pressure - Goodman AMH8 Service Instructions Manual

SERVICING
Orifices should be treated with care in order to prevent
damage. They should be removed and installed with a box-
end wrench in order to prevent distortion. In no instance
should an orifice be peened over and redrilled. This will
change the angle or deflection of the vacuum effect or en-
training of primary air, which will make it difficult to adjust
the flame properly. This same problem can occur if an ori-
fice spud of a different length is substituted.
WARNING
D ALL G
ISCONNECT AS AND
1. Check orifice visually for distortion and/or burrs.
2. Check orifice size with orifice sizing drills.
3. If resizing is required, a new orifice of the same physi-
cal size and angle with proper drill size opening should
be installed.
A
The length of Dimension "A" determines the angle of Gas
Stream "B".
A dent or burr will cause a severe deflection of the gas
stream.
S-307 CHECKING GAS PRESSURE
Gas Supply Pressure Measurement
CAUTION
T
O 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 mea-
56
E P S
LECTRICAL OWER UPPLY.
GAS
STREAM B
DENT OR
BURR
GAS
STREAM B
sure the gas supply pressure, use the following proce-
dure.
WARNING
D
ISCONNECT ELECTRICAL POWER AND SHUT OFF GAS SUPPLY.
1. After turning off gas to furnace at the manual gas shut-
off valve external to the furnace, remove burner com-
partment door to gain access to the gas valve.
2. Connect a calibrated water manometer (or appropri-
ate gas pressure gauge) at either the gas valve inlet
pressure tap or the gas piping drip leg as shown in the
following figures.
NOTE: At either location, a hose fitting must be installed
prior to making the hose connection.
NOTE: Use apapter kit #0151K00000S to measure gas
pressure on White-Rodgers and 36G54 gas valves.
GAS LINE
GAS SHUTOFF VALVE
DRIP LEG CAP
WITH FITTING
MANOMETER HOSE
Measuring Inlet Gas Pressure
(Alternate Method)
3. Turn ON the gas and electrical power supply and op-
erate the furnace and all other gas consuming appli-
ances on the same gas supply line.
4. Measure furnace gas supply pressure with burners fir-
ing. Supply pressure must be within the range speci-
fied in the following table.
INLET GAS SUPPLY PRESSURE
Natural Gas Minimum: 4.5" w.c.
Propane Gas Minimum: 11.0" w.c.
If supply pressure differs from above, make necessary
adjustments to pressure regulator, gas piping size, etc.,
and/or consult with local gas utility.
GAS LINE
TO FURNACE
OPEN TO
ATMOSPHERE
MANOMETER
Maximum: 10.0" w.c.
Maximum: 13.0" w.c.