A.O. Smith Water Heater AT-H3S-DV-N

Turn off all electric power to the water heater

Turn the manual gas valve located on the outside of the unit to the off position

Ensure all safety precautions are followed to prevent fire or explosion

Shut off the manual gas valve on the gas supply line

Remove the screw from the pressure port on the gas inlet of the water heater

Connect the manometer to the pressure port and zero the manometer

Ensure the discharge area is secure for disposal

Manually operate the pressure relief valve to check for correct operation

Did the relief valve discharge during normal operation?

If yes, describe the issue and contact a service technician

Close the manual gas shutoff valve

Turn off power to the unit and wait a couple of seconds. Turn on again.

Wait 30 seconds, and then turn off power to the unit.

Is the heater part of an Easy-Link or Multi-Unit System?

If yes, close the inlet and outlet water valves to isolate the heater.

Check the venting system for the following issues

Check the burner for the following issues

Turn off the electrical power supply

Close the manual gas shutoff valve

Close the manual water control valve

Ensure area around water heater is free from dust, debris, and contaminants

Check that combustion and ventilation air openings are not blocked

Inspect the screen of the termination for blockages

Remove any combustible materials, gasoline, or flammable vapors and liquids from the area