5. Shut off the gas at the manual
gas valve and remove the
U-Tube manometer.
6. Replace the pressure tap plug
before turning on the gas.
If the supply gas line pressure is
above these ranges, install an in-line
gas regulator to the furnace for
natural gas units. With LP gas, have
the LP supplier reduce the line
pressure at the tank regulator.
If supply gas line pressure is below
these ranges, either remove any
restrictions in the gas supply piping
or enlarge the gas pipe. With LP gas,
have the LP supplier adjust the line
pressure at the tank regulator.
Manifold Gas Pressure Measure-
ment. Natural gas manifold pressure
should be 3.5" w.c. LP gas manifold
pressure should be 10.0" w.c. Only
small variations in gas pressure
should be made by adjusting the
pressure regulator.
1. With the gas to the unit shut off
at the manual gas valve, remove
the 1/4" pipe thread pressure tap
plug in the gas manifold.
2. Connect a U-Tube manometer
to this pressure tap.
3. Turn on the gas supply and
operate the furnace.
4. Note the manifold gas pressure
on the manometer.
A. 3.5" w.c. for natural gas.
B. 10.0" w.c. for LP gas.
5. To adjust the pressure regulator,
remove the regulator cap.
6. Turn the adjustment screw
clockwise to increase pressure,
or counterclockwise to decrease
pressure.
7. Securely replace the regulator
cap.
8. Shut off gas at the manual gas
valve and remove the U-Tube
manometer.
9. Replace the manifold pressure
tap plug before turning on
the gas.
FIGURE 66
MANIFOLD PLUG LOCATION
r
FIGURE 67
MANIFOLD PRESSURE READING
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60
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