How to Light a Propane Furnace

Jack S. Waverly

Propane furnaces can be one of the more cost-effective and more efficient methods of heating a home or camper. While propane furnaces are easy to maintain, they have certain steps and guidelines that must be used when lighting them. LP gas, or liquid propane, is highly combustible and can explode if an open air flow meets a sudden burst of gas. For this reason, proper cleaning and safety measures must be used when lighting a propane furnace. With this in mind, here is how to safely light a propane furnace.

  1. Locate the valve control on the furnace. For wall furnaces, this should be a round knob on top. For floor furnaces, this is the round knob at the bottom of the furnace. The controls will be marked with "Off," "Pilot," "On" and possibly different heating levels numbering up to 5. Turn the valve control to the "Off" position. Wait three to five minutes for any gas fumes to safely dissipate.

  2. Check to make sure nothing is obstructing the pilot light assembly. If you need to, clean the pilot light assembly with a thin wire brush or compressed air. Be sure to turn off the gas feed while cleaning at any time by simply turning the valve to the "Off" position.

  3. Turn the valve to the "Pilot" position on the settings. This is the only setting that will ignite the LP gas to start the furnace. You should hear the gas escaping the ignition line. If you smell a strong odor of rotten eggs, this means you have a leak and should turn the valve back to the "Off" position immediately. If there is no smell, proceed to the next step. Make sure the flame is hitting the thermocouple, the long bar crossing overhead of the pilot light assembly.

  4. Light a match, and hold the flame to the pilot light opening. If you are using a newer wall furnace, simply hold down the control knob to force gas through the pilot light assembly. Then press and hold the "Reset" button on the control until the pilot light is burning steady. On some wall-mounted furnaces, you will have to click start the ignition button in the middle of the control to get the pilot to light. This may take up to five tries to be successful.

  5. Set the valve control to the "On" position or whatever level you want. Wait 10 seconds to make sure the pilot light remains on and the thermocouple is receiving gas and is heating. Look at the flame--if it is a low blue-yellow, you have a good lighting. If you have a high yellow or orange flame, you may have air in the line or a leak. If you have a very low blue light, you are running out of fuel.