What Do the Different Furnace Flame Colors Mean? | Eanes Heating & Air
What Do the Different Furnace Flame Colors Mean? | Eanes Heating & Air


What Do the Different Furnace Flame Colors Mean?

What Do the Different Furnace Flame Colors Mean? | Eanes Heating & Air

Want to know the best way to determine if your furnace is operating safely and at peak efficiency? Check the furnace flame. The color of this flame will tell you everything you need to know about the combustion process. Keep reading to see what color the flame should be and what colors to be wary of.

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What Are Furnace Flame Colors?

The pilot light in your furnace contains a small flame that appears every time the system runs heating cycles. The color of the flame indicates how much oxygen the furnace receives and how effective the combustion process is.

​​What Color Should Your Furnace Flame Be?

The furnace flame should always be blue. A blue flame means the furnace is receiving adequate oxygen and is burning the fuel supply properly. Any other color is cause for concern.

What Do the Different Furnace Flame Colors Mean?

If the furnace flame is any color but blue, something has gone awry in the combustion process. Start by turning off the furnace, then contact your local Eanes technician for immediate assistance.

Blue Flame

What Do the Different Furnace Flame Colors Mean? | Eanes Heating & Air

The more oxygen your furnace receives, the hotter the flame will be. The hotter the flame, the bluer it appears. A blue flame indicates efficient combustion and optimal heat production. If the blue flame contains a tinge of yellow at the top, don’t sweat it. That’s completely normal.

Yellow Flame

A fully yellow flame, on the other hand, isn’t normal. It results in moderate heat production, a higher monthly energy bill, and means one of a few things has occurred:

  • Carbon monoxide production, which is a colorless, odorless gas that can be fatal when inhaled in large amounts
  • A gas leak
  • Inefficient combustion process

Orange Flame

An orange flame means gas is being wasted and carbon monoxide is being produced. This inefficient combustion process causes stunted heat production and higher energy bills.

Green Flame

A green flame means your furnace has a buildup of dirt and soot that produces inefficient combustion and inadequate heat production.

What Causes Yellow, Orange, and Green Furnace Flame Colors?

Below is a list of the top four reasons why furnace flames turn yellow, orange, and green.

  1. Inadequate oxygen supply
  2. Combustion issue
  3. Dirty furnace
  4. Moist or polluted fuel supply

How to Ensure Proper Combustion

While some factors are out of your control when it comes to furnace operation, here are six practical steps you can take to ensure proper combustion.

  1. Periodically check the pilot light flame color
  2. Install carbon monoxide detectors if you don’t already have them
  3. Regularly replace the batteries in your carbon monoxide detector, which we recommend doing once to twice annually
  4. Keep furnace vents free from dust and debris, and replace them regularly. The general rule of thumb is to replace pleated filters once annually and fiberglass filters quarterly for optimal furnace efficiency.
  5. Keep the burners clean
  6. Schedule furnace maintenance at the beginning of each heating season

Schedule a Furnace Inspection With Eanes Home Comfort

Is your furnace flame yellow, orange, or green? Trust Eanes Home Comfort to make things right. Our licensed technicians will identify the problem and offer a solution that provides optimal furnace operation and cost savings—whether it be maintenance, repairs, or a unit replacement. We’ll do whatever it takes to protect your home, comfort, and your family.