Can Pilot Lights Be Too Big? (Proper Size And How To Adjust)

A gas fireplace is a comforting amenity to have in your home. It is a feature that offers warmth, ambiance and is easy to use. Simply press a button or flip a switch, and within seconds, you have a cozy fire right in your room. So, you might be surprised when you turn on your fireplace and it does not light. What gives? Perhaps the pilot light is too large.

A pilot light needs to be around ½ inch and can cause issues if it’s larger than it needs to be. A slightly larger pilot light may be no cause for concern; however, if it’s too large, it can lead to issues in igniting your gas fireplace. Knowing when your pilot light is ineffective will assist in preventing ignition problems and avoiding unnecessary repairs.

But how can you pinpoint when your pilot light is too large? What are the negative effects? And how can you adjust it so that it’s the correct size again? We’ll be covering all of that in this article!

Can A Pilot Light Be Too Large?

A pilot light can be longer than it should be. A pilot light should only be about ½ of an inch. A healthy pilot light is described as low and blue in color. An ill-adjusted pilot light can happen over time with use or even with a new install. Generally, this is an issue of adjustment, although sometimes it can be a bigger problem that requires a professional’s help.

Why does it matter if the pilot light is larger than ½ inch? Well first, it is important to know how a pilot light functions. Your pilot light is used in two ways: 1) to warm up the thermocouple; and2) to light the fire (or appliance—a pilot light can also be found on furnaces and water heaters).

The Thermocouple

A thermocouple uses pieces of metal, which generate electricity when heated. This electric current controls the gas valve. Without heat applied to the sensors, there is no electricity being generated. Without electricity, the valve closes. This, in turn, keeps the pilot light ignited and opens the gas valve when the fireplace is turned on.

The thermocouple functions as a safety feature because if the pilot light goes out, the thermocouple cools and shuts off the gas valve. You want this to happen because if the valve does not shut off, gas will build up, and when the pilot light comes back on, it can cause a dangerous combustion.

The Pilot Light

So, returning to our pilot light, if the pilot light is too large, it runs the possibility of shooting straight up (like a candle), causing the flame to miss the thermocouple sensors. This could cause the thermocouple to not heat properly and shut off your pilot light.

When the pilot light is the correct size, it is blue in color and engulfs the thermocouple sensors within its flame.

What Are The Cons Of A Large Pilot Light?

  • Ignition issues. If the pilot light is too large, you run the risk of having problems lighting the gas fireplace.
  • Thermocouple malfunction. If the flame is too large and does not properly heat the thermocouple, then the gas valve will shut off. This eliminates the pilot light and your gas fireplace will not turn on.
  • Costly. An excessive pilot light means that you are using extra gas which will end up costing you more money than is necessary.
  • Noise concern. If the pilot light is too large, you might hear a roaring sound. This can indicate the light is too large.

Signs Your Pilot Light Is Too Large

You can run a few at-home diagnostics to determine if your pilot light is too large. Color, size, and direction are a few indicators that will help you narrow down if your pilot light is oversized.

  1. Color. If the flame is mostly yellow in color, this may be an indicator that your pilot light is too large. A correct pilot light is described as being low and blue.
  2. Size. The flame should not be longer than ½ inch or exceed noticeably past the thermocouple sensors.
  3. Direction. If the flame shoots straight up, it may not be engulfing the thermocouple sensors.

Signs the pilot light is weak:

  1. The pilot light constantly goes out.
  2. The main burners do not light.
  3. The light is low and blue, but does not fully engulf the thermocouple sensors.

Can A Pilot Light Be Adjusted?

A pilot light can be adjusted by turning a knob on the control panel of your fireplace. Sometimes the adjuster is also a screw in which you will need to use a screwdriver to adjust the pilot light. Depending on the model, you either need to turn the knob or screw clockwise or counterclockwise.

The control panel. Some control panels have a hi-lo knob that can be rotated to adjust the pilot light. Other times the adjustment will require using a screwdriver to turn a screw either clockwise or counterclockwise to adjust the flame height. Consult the user manual for your fireplace to see where the pilot light adjuster is located on your model.

Clean the pilot light orifice. If the pilot light is not coming on or is weak, this could mean something is clogging the opening to the pilot light. You can try to resolve this issue by gently cleaning the opening. This problem is prone to happen if you have turned off your pilot light for some time. Spider webs and insects could be the cause of a blockage.

Purchase new parts. If all else fails and you are still having issues with your pilot light being too large, too small, or having thermocouple failure, it could mean that some parts need replacing. It is not uncommon for the pilot light to be working appropriately, yet the fireplace is not lighting.

This could indicate the thermocouple has failed and the gas valve will not open. Since replacing parts requires working with gas lines, it is best to seek out professional help in replacing these parts to avoid potential gas leaks.  

Dan Westfield

Hi everyone! My name is Dan and I currently have two fireplaces, a wood-burning and a gas one. I cannot live without them and love to share my passion with you all!

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