How Do You Light a Furnace?

Lighting a gas furnace involves turning off the pilot valve, lighting the pilot with a long fireplace match, then turning the gas knob to the On position. This process takes less than half an hour.

  1. Turn on your indoor thermostat

    Make sure that your thermostat is set to the heat mode. Set the thermostat to a temperature that requires the furnace to come on, such as 75 degrees Fahrenheit.

  2. Turn off the pilot valve

    Locate the pilot valve, which is usually near where the furnace connects to the main gas line. Find the gas knob with the labels Off, Pilot and On. Turn the knob to the Off position. Wait for a few minutes before proceeding.

  3. Light the pilot

    Locate the pilot. Because the pilot can be difficult to reach, use a long fireplace match or a barbecue lighter. Turn the gas knob to Pilot. Hold down the button for about 30 seconds, and place the match tip close to the pilot. Check that the pilot light remains lit for another minute or so. Turn the gas knob to On. Repeat the process if the pilot does not stay lit.

  4. Check the thermostat

    Once the pilot remains lit, change your thermostat to the desired temperature.