What Causes a Furnace Pilot Light to Go Out?

If you have a relatively old furnace, chances are it uses a standing pilot light for ignition, which must be kept on at all times. In today’s post, Stone Heating and Air takes a look at what causes pilot lights to go out and what can be done about this.

Furnace Pilot Light

How Pilot Lights Work

A pilot light provides the flame needed by a furnace to light the gas from the main burner. It’s fed by a small amount of gas from a dedicated pipe. When you turn on your furnace for the season, the pilot light is lit like a stove and stays on as long as the furnace is in use. To prevent gas leaks in the event the flame goes out, a pilot light has a thermocouple, a safety valve that stops the flow of gas if it doesn’t sense a flame on the burner.

What Causes Pilot Lights to Go Out?

The following are some of the most common reasons why a pilot light would go out.

  • Temporary gas shortage. Most of the time, a pilot light will go out not because of a furnace problem but because of a temporary gas shortage. The demand for natural gas is high during the winter season, and there may be periods when there’s not enough gas to keep the pilot light on. If you have a gas stove, you can use it to check whether or not you’re getting gas. Contact your utility company if you’re not getting gas in your utility lines.

  • Drafts. The pilot light is housed in an enclosure that prevents drafts from blowing it out, but it can still happen. It can be easily relit, but if this is a persistent problem, you should have your furnace inspected by an HVAC technician.

  • Soot in the pipes. As natural gas burns, it produces soot that can accumulate in the pipes and block gas flow. This can happen sight unseen, but there are often signs such as a yellow or red flame instead of a blue one, which means the pilot light isn’t getting enough fuel. An almost fully-blocked pipe line will cause the pilot light to go on and off. Keeping up with scheduled HVAC maintenance can help prevent blocked pipes and keep your pilot light on.

Stone Heating and Air is your leading provider of heating and air conditioning services. Give us a call at (541) 855-5521. You can also fill out our contact form to schedule an appointment.

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