Why Does My Gas Furnace Pilot Light Keep Going Out?

January 10, 2014

Tired of your gas furnace pilot light going out? It’s frustrating, especially in the frigid Kansas City area winters.

Here are a few common causes of this problem and how to fix them.

Problems with the thermocouple

The thermocouple is the copper rod you see the pilot flame hitting. It’s a safety device that controls a small valve to shut off gas going to the pilot light if the flame goes out.

If it didn’t shut the gas valve, all that gas could get into your home. If it was ignited, it’d cause an explosion.

So, the thermocouple is like a lifeguard, standing watch until something goes wrong.

There are a few problems related to the thermocouple that can cause the pilot light to go out: 

  • Malfunction- If your thermocouple is broken, it will shut the valve even if the pilot light was working fine. And you won’t be able to open the valve manually, either. A professional HVAC contractor needs to replace the thermocouple if that’s the case. Don’t worry, they’re inexpensive.
  • Soot buildup- Soot on the thermocouple will block the flame, so the thermocouple won’t work properly. Gently clean the soot off with a wire brush.
  • Pilot not enveloping the top of the thermocouple- The pilot light flame needs to envelop the top part of thermocouple rod so the thermocouple knows the flame is on. 

Problems with the pilot light

The pilot flame should be a strong blue cone (seen above). If the pilot flame is a lazy, yellow flame, it’s not hot enough and won’t properly reach the thermocouple.

A lazy yellow flame is caused by a lack of air, often due to dirt getting in the pilot light opening (called an orifice). Get a professional to clean the opening.

Consider a high efficiency furnace for your Kansas City area home

You furnace is probably 20 years old if it has a pilot light. if that’s the case, you will need a new one soon since a furnace’s lifespan is about 18-20 years.

Old furnaces with pilot lights waste a lot of gas, too. So we’d strongly recommend upgrading to a new high efficiency furnace to lower your energy bills.

If you’re not sure you need to replace your furnace yet, read our article 4 Warning Signs You Need to Replace Your Furnace (Before It Dies).

Santa Fe Air Conditioning and Heating serves Olathe, Overland Park, Lenexa, Leawood, Shawnee, Gardner and the Kansas City area. For more information, contact us online


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