A.O. Smith Water Heater HWB-399

Oil the three oil cups (2 on the motor, 1 on the pump) as instructed on the oil tube supplied with the unit.

Lubricate the three oil cups at least once every four months during the heating season.

For combination heating-cooling systems, lubricate every four months year-round.

Use 2 or 3 teaspoonsful in bearing oil cups.

Use 10 or 12 drops in the motor oil cups.

Attach the leads from a millivolt meter to the thermocouple and junction block and record the reading

Is the thermocouple reading above 14 to 18 millivolts?

Transfer the lead on the junction block to other terminal and record the reading

Is the voltage supply reading between 8 to 14 millivolts?

If the reading is less than 8 millivolts, describe the issues found with the junction block connections and protector switch leads

Enter the millivolt drop across the contacts

Inspect the operation of all safety devices including low water cutoffs

Flushing of Low Water Cutoff Device

Flush the low water cutoff device of the float type

Is a more frequent inspection necessary based on current water conditions?

Pilot Burner - Electronic Ignition

Open fused disconnect switch or shut off electrical power to the boiler.

Turn the gas valve control knob counterclockwise to the 'PILOT' position.

Close fused disconnect switch to restore electrical power to the boiler.

Did the pilot ignite with the combination gas valve knob set at 'PILOT' and the system calling for heat?

Adjust pilot flame to cover 3/8" to 1/2" (10-12mm) of the sensing probe tip.

Did the main burner fail to light after pilot ignition?

Check the following if the main burner fails to light

Replace valve if electrical power and gas are present but the valve does not open when system calls for heat.

Ensure the protector switch reset button is not depressed

Remove leads from the switch and attach to test flashlight leads

Testing with Model N22T Test Kit

Depress reset button on switch (ensure water temperature is below 200°F)

Does the lamp light up after depressing the reset button?