SERVICING
42
Gas Manifold Pressure Measurement and Adjustment
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CAUTION
NOTE:
Use adapter kit #0151K00000S to measure gas
pressure on White-Rodgers 36J22 gas valves.
Only small variations in gas pressure should be made by
adjusting 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.
WARNING
H
IG
H
V
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AGE
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ISC
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ALL
ELEC
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HUT
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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 appropriate
gas pressure gauge) at the gas valve outlet pressure
tap. Refer to
Measuring Gas Pressure: Single Stage
Valves
figure for single stage valve outlet pressure tap
connections.
L
INE V
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L
T
AGE N
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W PRESEN
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WARNING
3. Turn ON the gas and electrical power supply and operate
the furnace.
4. Measure gas manifold pressure with burners firing. Adjust
manifold pressure using the table below.
Natural Gas
3.5" w.c.
Propane Gas
10.0" w.c.
Manifold Gas Pressure
The final manifold pressure must not vary more than ± 0.3
“ w.c. from the above specified pressures. Any necessary
major changes in gas flow rate should be made by changing
the size of the burner orifice.
5. White-Rodgers 36J22 Valves:
a. Back outlet pressure test screw (inlet/outlet pressure
boss) out one turn (counterclockwise, not more than
one turn).
b. Attach a hose and manometer to the outlet pressure
outlet pressure boss.
c. Turn ON the gas supply.
d. Turn on power and close thermostat “R” and “W1”
contacts to provide a call for heat.
e. Measure the gas manifold pressure with burners firing.
Adjust manifold pressure using the
Manifold Gas
Pressure
table shown below.
f. Remove regulator cover screw from the outlet pressure
regulator adjust tower and turn screw clockwise to
increase pressure or counterclockwise to decrease
pressure. Replace regulator cover screw.
i. Turn off all electrical power and gas supply to the
system.
j. Remove the manometer hose from the hose barb fitting
or outlet pressure boss.
k. Turn outlet pressure test screw in to seal pressure port
(clockwise, 7 in-lb minimum).
6. Honeywell VR8215 Valve:
a. Remove the outlet pressure boss plug. Install an 1/8”
NPT hose barb fitting into the outlet pressure tap.
b. Attach a hose and manometer to the outlet pressure
barb fitting.
c. Turn ON the gas supply.
d. Turn on power and close thermostat “R” and “W1”
contacts to provide a call for low stage heat.
e. Measure the gas manifold pressure with burners firing.
Adjust manifold pressure using the
Manifold Gas
Pressure
table shown.
f. Remove regulator cover screw from the outlet pressure
regulator adjust tower and turn screw clockwise to
increase pressure or counterclockwise to decrease
pressure. Replace regulator cover screw.
i. Turn off all electrical power and gas supply to the
system.
j. Remove the manometer hose from the hose barb fitting
or outlet pressure boss.
k. Remove the 1/8” NPT hose barb fitting from the outlet
pressure tap. Replace the outlet pressure boss plug
and seal with a high quality thread sealer.
WARNING
H
IG
H
V
O
L
T
AGE
D
ISC
O
NNEC
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ALL
ELEC
T
RICAL P
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WER AND S
HUT
OFF
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PPL
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ALLING
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DAMAGE
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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 operation.
