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Pilot Adjustment
1. Set system selector switch at OFF position to shut off unit.
Turn off power to unit.
2. Remove screw cap cover on pilot gas valve to expose
adjusting screw (See Fig. 36).
3. Turn valve knobs to pilot position.
4. Turn onpower to unit. Set system selector switch to HEAT
position and set thermostat to a setting that will call for
heat. Pilot ignites.
5. With a small screwdriver, turn adjustment screw untilflame
fully engulfs sensor. Flame can be observed through view
port (Fig. 37).
6. Turn off power to unit. Replace cap on pilot gas valve.
Return valve knob(s) to original position.
7. Check for proper burner operation by cycling the burn-
ers. Wait 30 seconds between burner cycles.
8. Check that all unit panels are in place before leaving unit.
Gas Valve Adjustment
NATURAL GAS — The gas valve opens and closes in re-
sponse to the thermostat or limit control.
When power is supplied to valve terminals 3 and 4, the
pilot valve opens to the preset position. When power is sup-
plied to terminals 1 and 2, the main valve opens to its preset
position.
The regular factory setting is stamped on the valve body
(3.5 in. wg).
To adjust regulator:
1. Set thermostat at setting for no call for heat.
2. Turn main gas valve to OFF position.
3. Remove
1
⁄
8
-in. pipe plug from manifold or gas valve pres-
sure tap connection. Install a suitable pressure-measuring
device.
4. Set main gas valve to ON position.
5. Set thermostat at setting to call for heat.
6. Remove screw cap covering regulator adjustment screw
(See Fig. 36).
7. Turn adjustment screw clockwise to increase pressure or
counterclockwise to decrease pressure.
8. Once desired pressure is established, set thermostat set-
ting for no call for heat, turn off main gas valve, remove
pressure-measuring device and replace
1
⁄
8
-in. pipe plug
and screw cap.
Fig. 34 — Cooling Charging Chart, 48HJ017
Fig. 35 — Cooling Charging Chart, 48HJ025
Fig. 36 — Gas Valve
MAIN BURNER
SECTION
FLUE BOX
COVER
VIEW
PORT
PRIMARY AIR
SHUTTER
Fig. 37 — Typical Heating Section
22