Carrier 48HC D17 Series Service And Maintenance Instructions page 46

Gas Valve
All unit sizes are equipped with 2- - stage gas valves. See
Fig. 58 for locations of adjustment screws and features on
the gas valves.
ON/OFF
SWITCH
NPT INLET
INLET
PRESSURE TAP
Fig. 58 - - Gas Valve
Adjusting Gas Valve Pressure Settings
IMPORTANT: Leak check (using a mixture of soapy
water or leak detection fluid) all gas connections
Fig. 57 - - Unit Control Box/IGC Location
including the main service connection, gas valve, gas
spuds, and manifold pipe plug. All leaks must be repaired
before firing unit.
Check Unit Operation and Make Necessary
Adjustments
REGULATOR
COVER SCREW (2)
NOTE: Gas supply pressure at gas valve inlet must be
PLASTIC ADJUST
within specified ranges for fuel type and unit size. See
SCREW (2)
Tables 7, 8, 9, and 10.
REGULATOR SPRING (2)
(PROPANE - WHITE
NATURAL - SILVER)
LOW STAGE
GAS PRESSURE
REGULATOR
ADJUSTMENT
NPT OUTLET
MANIFOLD
PRESSURE TAP
C12066A
46
IGC Board
IGC Board
1. Shut off electrical power supplies to unit and install
lockout tag.
2. Shut off manual gas shut off valve located on gas
supply line.
3. Remove manifold pressure tap plug from manifold
and connect pressure gauge or manometer. See Fig.
56.
4. Turn on electrical supply.
5. Open manual shut off valve, then turn on unit main
gas valve.
6. Set room thermostat to call for heat. Verify
high- - stage heat operation before attempting to adjust
manifold pressure.
7. When main burners ignite, check all fittings,
manifold, and orifices for leaks.
C10337