Lochinvar 497 - 2067 service manual Combustion and ventilation air

8 Maintenance

Heat exchanger cleaning

1.While burners are removed, check the heat exchanger surface for sooting. If present, heat exchanger must be cleaned and problem corrected. Proceed as follows.

2.Remove gas manifold(s)/orifice assemblies as described in steps 1 through 5 in Burner Removal and Cleaning, page 57.

3.Disconnect wiring from the hot surface igniter and hose from the burner pressure tap.

4.Remove inner jacket panel mounting screws and slide door assembly out toward front of the unit. Use caution to prevent damage to the refractory and hot surface igniter.

5.Check “V” baffles and frame runners along front and back edges of heat exchanger. Remove and clean if necessary.

6.Remove soot from heat exchanger with a stiff bristle brush. Use a vacuum to remove loose soot from surfaces and inner chamber.

7.The heat exchanger can be removed by sliding towards the front of the unit. Once the heat exchanger is removed from the unit, a garden hose can be used to wash the tubes to ensure that all soot is removed from the heat exchanger surfaces. Note: Do not wet the unit’s refractory.

8.Ensure that all burner ports are cleaned to remove any soot. See Burner Removal and Cleaning, page 57.

9.Carefully reinstall the heat exchanger, “V” baffles, and frame runners if removed from the unit. Note: Make sure frame runners seal securely where they contact the front and rear compartment refractory.

10.Carefully reinstall inner jacket panels, burners, manifolds, wires and hoses. Use new gasket material to ensure a proper air seal.

11.Reassemble all gas and water piping. Test for gas leaks.

12.Reassemble outer jacket panels.

13.Cycle unit and check for proper operation.

Electrical

This unit uses a transformer to supply a low voltage control circuit. The voltage on the secondary side should be 24 to 28VAC when measured with a volt meter. Larger models have a 7AMP circuit breaker provided on the secondary side of the transformer. A tripped circuit breaker indicates a short in the 24VAC controls that must be corrected.

Installation & Service Manual

Combustion and ventilation air

Combustion air filter

See Combustion Air Filter, page 13.

Air flow

Check frequently to be sure the flow of combustion and ventilation air to the unit is not obstructed.

Combustion air fan

These units use a fan-assisted combustion process. These units have one fan to supply combustion air to the burners.

Fan cleaning

Check combustion air fan every six months. Clean fan as required only when installed in a dusty or dirty location. Oiling is not required.

Combustion air fan adjustment

The combustion air fan is factory preset and should not need adjustment in most cases. Follow the steps below to adjust the fan if a continuous Low Air Status Code occurs.

Check for proper installation and draft in the venting system. Correct as required.

Adjusting air pressure

The following is a recommended method for setting the air pressure for the fan.

Setup procedure

To the left of the fan is an air pressure switch with a large and small tube delivering pressure from points inside the unit (see FIG. 8-2). The pressure in the large tube is the chamber pressure. By disconnecting the cap from the tee in the hose and connecting it to the "(+)" side of a manometer, you can read the air chamber pressure.

Upon a call for heat, the fan will run for about 90 seconds before going into soft lockout. If necessary, turn the power to the unit OFF and then back ON again to recycle the fan.

Note: If the unit has been firing recently, allow the unit to cool for five minutes with the fan running before beginning the adjustment procedure.

Note: Retain the plastic cap removed from the tee for reinstallation when complete.

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