Carrier 48PG20-28 specifications Gas Valve

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. 40).
7.	Turn adjustment screw clockwise to increase pressure or
	counterclockwise to decrease pressure.
8.	Once desired pressure is established, set unit setting
	for no call for heat, turn off main gas valve, remove

2 LEADS, #18 WIRE 1/32 INSULATION,	REGULATOR
600V. MAX., 105°C	ADJUSTMENT SCREW
	(REMOVE COVER)

OUTLET PRESSURE TAP (PLUGGED) 1/8-27 N.P.T. THDS.

pressure-measuring device, and replace 1/8-in. pipe

plug and screw cap.

High Altitude — For high altitude applications greater than 2000 ft the heat input rate should be reduced. The higher the altitude is above sea level, the less oxygen is in the air. See Table 32 for orifice sizing. A high altitude kit is available to convert unit for altitudes up to 7,000 ft.

ON

OFF

INLET PRESSURE TAP (PLUGGED)

1/8 - 27 N.P.T. THDS.

D-1		D-2	RECEPTACLE AND
			TAB COMBINATION
W-1		C1
			TERMINAL
		C2
PILOT ADJ.	W-2		PILOT CONNECTION
			FOR 1/4” O.D. TUBING
			(PLUGGED)

RECEPTACLE TERMINAL

Main Burners — For all applications, main burners are factory set and should require no adjustment.

MAIN BURNER REMOVAL

1.Shut off (field-supplied) manual main gas valve.

2.Shut off power to unit.

3.Remove gas section access panel.

4.Disconnect gas piping from gas valve inlet.

5.Remove wires from gas valve.

6.Remove wires from rollout switch.

7.Remove sensor wire and ignitor cable from IGC board.

8.Remove 2 screws securing manifold bracket to basepan.

9.Remove 2 screws that hold the burner assembly to vesti- bule plate.

10.Lift burner/manifold assembly out of unit.

SEE DETAIL “C”

Fig. 40 — Gas Valve

CLEANING AND ADJUSTMENT

1.Remove burner rack from unit as described in Main Burner Removal section above.

2.Inspect burners, and if dirty, remove burners from rack.

3.Using a soft brush, clean burners and crossover port as required.

4.Adjust spark gap. See Fig. 41.

5.Reinstall burners on rack.

6.Reinstall burner rack as described above.

Fig. 41 — Spark Gap Adjustment

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