21
NATURAL Min. 5.0" W.C., Max. 10.0" W.C.
PROPANE Min. 11.0" W.C., Max. 14.0" W.C.
If operating pressures dier from above, make necessary
pressure regulator adjustments, check piping size, etc.,
and/or consult with local utility.
The gas valve has a pressure tap to facilitate measurement
of the manifold pressure. The manifold pressure must be
measured with the burners operating.
1. With disconnect switch open, remove eld connected
thermostat wire from terminal R, W1 and W2 on TB1.
Place jumper wire between R, W1 and W2 to engage
high stage heat.
2. See Figure in gas input check section for gas valve
adjustment.
To adjust the pressure regulator, remove the adjustment
screw cover on the gas valve. Turn the adjustment screw
out (counterclockwise) to decrease pressure, turn in
(clockwise) to increase pressure. Only small variations
in gas ow should be made by means of the pressure
regulator adjustment. Any major changes in ow should
be made by changing the size of the burner orices. The
measured input rate to the furnace must not exceed the
rating specied on the unit rating plate.
For natural gas, the high stage manifold pressure must be
between 3.2 and 3.8 inches water column (3.5 nom inal).
Low stage manifold pressure must be between 1.7 to 2.3
inches water column (2.0 nominal).
3. To set low re rate, open disconnect switch and
remove jumper from R to W2. To set low re manifold
pressure, repeat steps above. Refer to Figure in gas
input check section for location of high and low stage
pressure adjustment.
For propane gas, the manifold pressure must be between
9.7 and 10.3 inches water column (10.0 nominal). Low
stage manifold must be between 5.7 and 6.3 inches water
column (6.0 nominal).
It is the responsibility of the contractor to adjust the gas
input to the unit.
To measure the gas input use a gas meter and proceed as
follows:
1. Turn o gas supply to all other appliances except the
unit.
Gas supply pressure and manifold pressure with the
burners operating must be as specied on the rating plate.
Gas inlet pressure must be checked and adjusted in
accordance to the type of fuel being consumed.
1. Close the manual gas valve external to the unit.
2. Turn o the electrical power supply to the unit.
3. Change heating setpoint to its lowest possible setting.
4. Remove the heat exchanger door on the side of the
unit by removing screws.
5. This unit is equipped with an ignition device which
automatically lights the main burner. DO NOT try to
light burner by any other method.
6. Move the gas control valve switch to the OFF position.
7. Wait ve minutes to clear out any gas.
8. Smell for gas, including near the ground. This is
important because some types of gas are heavier
than air. If you have waited ve minutes and you do
smell gas, immediately follow the warning WHAT TO
DO IF YOU SMELL GAS on page 2 of this manual.
If having waited for ve minutes and no gas smell is
noted, move the gas control valve switch to the ON
position.
9. Replace the heat exchanger door on the side of the
unit.
10. Open the manual gas valve external to the unit.
11. Turn on the electrical power supply to the unit.
12. Change heating setpoint to desired setting.
1. Connect a water manometer or adequate gauge to
the inlet pressure tap of the gas valve.
Inlet gas pressure can also be measured by removing the
cap from the dripleg and installing a predrilled cap with a
hose tting.
2. Put unit into heating cycle and turn on all other gas
consuming appliances.
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