A.O. Smith Water Heater HWB-300

Main Burner Characteristics Check

Verify main burner characteristics

Is there any accumulation of lint or foreign material?

Is there good flow of combustion and ventilating air to the unit?

Turn off electrical power and close the main manual gas shutoff valve

Allow boiler parts to cool before disassembly

Remove main burner manifold assembly from boiler

Remove loose foreign material with a vacuum

Turn off the electrical power, main manual gas shutoff, and pilot valves, if applicable.

Allow boiler parts and vent to cool before disassembly.

Remove the boiler draft diverter and vent pipe running to the chimney.

Check parts and chimney for obstructions and clean as necessary.

Remove burner from boiler and other metal parts as required to clean and vacuum the heat exchanger and combustion coils.

Refer to parts list supplied with this manual for disassembly aid.

Ensure all necessary tools and safety equipment are available

Verify that the inspection area is safe and accessible

Check for visible signs of water leaks in the following areas

Is there any evidence of water leakage?

Inspect for gas leaks in the following components

Is there any smell of gas or hissing sound indicating a leak?

Ensure the protector switch reset button is not depressed

Remove the leads from the switch from the thermocouple function block

Attach the leads from the switch to the leads from a test flashlight

Turn on the flashlight. Does the lamp light up?

Depress reset button on switch. Does the lamp light up?

If the lamp does not light, identify the issue

Shut off electric and gas supply to the unit

Remove pressure relief valve from outlet header assembly and install drain hose assembly

Install standpipe in tee of inlet line