36
Fig. 53 — Unit Control Box/IGC Location
Gas Valve
All unit sizes are equipped with 2-stage gas valves. See Fig. 54 for
locations of adjustment screws and features.
Fig. 54 — Gas Valve
ADJUSTING GAS VALVE PRESSURE SETTINGS
CHECK UNIT OPERATION AND MAKE NECESSARY
ADJUSTMENTS
NOTE: Gas supply pressure at the gas valve inlet must be within
specified ranges for the fuel type and unit size. See Tables 9-12.
1. Shut off all electrical power supply to the unit and install a
lockout tag.
2. Close the manual gas shutoff valve located on the gas supply
line.
3. Remove the manifold pressure tap plug from the manifold
and connect a pressure gage or manometer. See Fig. Shoul b.
4. Turn on the electrical supply.
5. Open the manual shutoff valve, then turn on the unit main gas
valve.
6. Set the room thermostat to call for heat. Verify high-stage
heat operation before attempting to adjust the manifold
pressure.
7. When the main burners ignite, check all fittings, manifold,
and orifices for leaks.
8. Adjust the high-stage pressure to the specified setting by turn-
ing the plastic adjustment screw clockwise to increase pres-
sure, and counterclockwise to decrease pressure.
9. Set the room thermostat to call for low-stage heat. Adjust the
low-stage pressure to the specified setting.
10. Replace the regulator cover screw(s) when finished.
11. With the burner access panel removed, observe the unit
heating operation in both high stage and low stage opera-
tion. Observe the burner flames to see if they are blue in
IMPORTANT: Leak check (using a mixture of soapy water or
leak detection fluid) all gas connections including the main ser-
vice connection, gas valve, gas spuds, and manifold pipe plug.
All leaks must be repaired before firing the unit.
PLASTIC ADJUST
SCREW (2)
REGULATOR SPRING (2)
(PROPANE - WHITE
NATURAL - SILVER)
LOW STAGE
GAS PRESSURE
REGULATOR
ADJUSTMENT
MANIFOLD
PRESSURE TAP
INLET
PRESSURE TAP
ON/OFF
SWITCH
REGULATOR
COVER SCREW (2)
NPT INLET
NPT OUTLET
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