Carrier 48TC*D08 Cleaning and Adjustment, Check Unit Operation and Make Necessary Adjustments

MANIFOLD PRESSURE TAP

GAS

VALVE

		BURNERS
		C09154
		Fig. 35 - Burner Tray Details
	6.	Remove igniter wires and sensor wires at the Integ-
		rated Gas Unit Controller (IGC). (See Fig. 36.)
48TC	7.	Remove the 2 screws that attach the burner rack to
		the vestibule plate. (See Fig. 33.)
	8.	Slide the burner tray out of the unit. (See Fig. 35.)
	9.	To reinstall, reverse the procedure outlined above.

Cleaning and Adjustment

1.Remove burner rack from unit as described in Re- moval and Replacement of Gas Train section, above.

2.Inspect burners; if dirty, remove burners from rack. (Mark each burner to identify its position before re- moving from the rack.)

3.Use a soft brush to clean burners and cross-over port as required.

4.Adjust spark gap. (See Fig. 37.)

5.If factory orifice has been removed, check that each orifice is tight at its threads into the manifold pipe and that orifice projection does not exceed maximum valve. (See Fig. 34).

6.Reinstall burners on rack in the same locations as factory-installed. (The outside crossover flame re- gions of the outermost burners are pinched off to pre- vent excessive gas flow from the side of the burner assembly. If the pinched crossovers are installed between two burners, the flame will not ignite prop- erly.)

RACEWAY	INTEGRATED GAS UNIT
	CONTROLLER (IGC)

HOLE IN END PANEL (HIDDEN)

C08454

Fig. 36 - Unit Control Box/IGC Location

7.Reinstall burner rack as described in Removal and Replacement of Gas Train section, above.

Gas Valve — All unit sizes are equipped with 2-stage gas valves. See Fig. 38 for locations of adjustment screws and features on the gas valves.

To adjust gas valve pressure settings:

IMPORTANT: Leak check all gas connections 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

NOTE: Gas supply pressure at gas valve inlet must be within specified ranges for fuel type and unit size. (See Table 5, 6, 7, and 8.)

1.Remove manifold pressure tap plug from manifold and connect pressure gauge or manometer. (See Fig. 35.)

2.Turn on electrical supply.

3.Turn on unit main gas valve.

4.Set room thermostat to call for heat. Verify high- stage heat operation before attempting to adjust mani- fold pressure.

5.When main burners ignite, check all fittings, mani- fold, and orifices for leaks.

6.Adjust high-stage pressure to specified setting by turning the plastic adjustment screw clockwise to in- crease pressure, counter-clockwise to decrease pres- sure.

7.Set room thermostat to call for low-stage heat. Adjust low-stage pressure to specified setting.

8.Replace regulator cover screw(s) when finished.

9.With burner access panel removed, observe unit heat- ing operation in both high stage and low stage opera- tion. Observe burner flames to see if they are blue in appearance, and that the flames are approximately the same for each burner.

10.Turn off unit, remove pressure manometer and re- place the 1/8 in. pipe fitting on the gas manifold. (See Fig. 35.)

Limit Switch

Remove blower access panel. Limit switch is located on the fan deck. (See Fig. 30.)

28