How do I test an ignition transformer on an oil heater?

Written by richard asmus
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How do I test an ignition transformer on an oil heater?
(Comstock/Comstock/Getty Images)

Oil heaters use an electric spark to ignite the oil. To generate this spark, a transformer connected to the electrical circuit of the home steps up the household voltage to 10,000 to 14,000 volts, which, when applied to an igniter, generates a spark. You can test the voltage output of the transformer by using a screwdriver to create a spark at the output. But since oil heater designs vary widely, you will need the mechanical ability to open your oil heater and expose the transformer without specific instructions.

Skill level:

Things you need

  • Screwdriver with insulated handle

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  1. 1

    Shut off the power to the oil heater.

  2. 2

    Open the oil heater maintenance panel to expose the transformer.

  3. 3

    Disconnect the electrical power wires to the motor. This prevents oil from spilling while you do the test.

  4. 4

    Apply power to the oil heater and turn it on.

  5. 5

    Touch the screwdriver to one of the output terminals of the transformer and slowly move it to the other terminal while still touching the first. The second terminal should arc to the screwdriver at about 1/2 inch away, and the arc should extend to about 3/4 inch as you move the screwdriver away. If the arc less than 1/2 inch or does not appear at all, the transformer is bad.

Tips and warnings

  • Oil heaters should be serviced by a qualified technician once a year to check for potential wear and tear.
  • While you have your oil heater taken apart, check the ceramic insulator on the igniter itself for dirt and cracks.
  • Use a screwdriver with a well-insulated handle on which the metal part does not extend past the back of the handle. Touching the 10,000 volts could cause a bad shock.

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