Checking Orifices; Checking Gas Pressure - Goodman Amana AMH8 Service Instructions Manual

SERVICING
S-306 CHECKING ORIFICES
No resizing should be attempted until all factors are
taken into consideration such as inlet and manifold gas
pressure, alignment, and positioning, specific gravity
and BTU content of the gas being consumed.
The only time resizing is required is when a reduction in
firing rate is required for an increase in altitude.
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 entraining of primary air, which will make it
difficult to adjust the flame properly. This same prob-
lem can occur if an orifice 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.
E P S
LECTRICAL OWER UPPLY.
GAS
STREAM B
DENT OR
BURR
GAS
STREAM B
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 pressure must be measured with the burn-
ers operating. To measure the gas supply pressure, use
the following procedure.
WARNING
D
ISCONNECT 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
compartment door to gain access to the gas valve.
2. Connect a calibrated water manometer (or appro-
priate 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 in-
stalled prior to making the hose connection.
NOTE: Use apapter kit #0151K00000S to measure gas
pressure on White-Rodgers and 36G54 gas valves.
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