How to fix yellow flame on gas furnace

How To Fix Yellow Flame on Gas Furnace | The Ultimate Guide


A gas furnace is an essential device that is used in several places. From industry to a house in a cold, winter country, gas furnaces have only one job- providing heat. Industrial gas furnaces are ‘big’ and have bigger purposes than to just warm you so they are regularly checked for any problems that may hamper your daily life. 

House gas furnaces, however, are just simple heating systems to keep you warm on a snowy morning. But that does not mean you should not check it sometimes. For example, what if, one morning, your furnace flame color has turned yellow from the blue?

When does a gas furnace flame turn yellow?

A furnace flame is usually blue with a slight yellow at the tip of its inner core. This indicates that the furnace is working efficiently. A yellow flame, however, can indicate major to minor potentially dangerous problems. Usually, there are three possible times for a yellow flame-

1) Incomplete combustion- When enough oxygen is not burned, a yellow flame is created. Yellow flames provide irregular heat, causing energy to be wasted, while may produce irritating or toxic smoke or gas like carbon monoxide.

2) Excessive gas- If the burning orifice is too large, the proportion of the natural gas burning with oxygen is altered, causing a yellow flame.

3) Black, sooty residue- One of the most important symptoms. The gas does not burn cleanly, resulting in a yellow flame. The creation of toxic gas is also possible.

How to fix a yellow flame in a furnace

How to fix a yellow flame in a furnace?

A yellow flame in a furnace should be repaired immediately. The longer the yellow flame stays, the more possibility of harmful gases being produced, one of which is carbon monoxide as mentioned above.

Carbon monoxide is an extremely dangerous gas produced from the incomplete combustion of oxygen. Named ‘silent killer’ by scientists, the gas can cause severe headache, nausea, hallucinations, and even death at high concentrations. 

One of the principal ways of fixing the yellow flame is to detect the problem before it becomes too late.

Possible steps to prevent a yellow flame

Unless there is a possible defect in the furnace or any other complexities leading to the yellow flame, if you can adjust the furnace’s burners’ air shutter, the yellow flame problem can be solved without the help of a professional.

1) Since you will only be using the furnace during the winter season, it is preferable to schedule brief heating maintenance with the help of professionals before you finally start using the furnace. In this way, you can stay relieved for the rest of the season.

2) Always keep an eye on the flame color, especially at the beginning and then every month thereafter.

3) If you notice any change in the color of the flame, from blue to yellow or any other color, contact a professional immediately. Possibly, the furnace’s burners have to be inspected and cleaned which may not be a job for you.

4) Observe for any accumulation of soot inside the furnace. It is very much possible that the furnace’s burners become blocked, therefore not allowing enough oxygen to burn and eventually leading to incomplete combustion.

5) Always keep a carbon monoxide detector in the house, preferably where the furnace has been set up. If the detector goes off, immediately turn off the furnace, ventilate the place and contact a professional to help you out. If you or any of your family members feel any symptoms of carbon monoxide inhalation, immediately contact a physician.

Over the years, the use of gas furnaces has considerably decreased and is often encouraged to decrease their usages due to their use of fossil fuels, a wealth that Earth is running out of quite fast. 

Engineers have, therefore, introduced electric heaters which use electricity instead of gas and hence, no flame color to be concerned about while you are getting warmed. They are also more efficient than furnaces. So, even if they might be slightly more expensive, it is preferred to replace the gas furnace with an electric heater. It is high time to remove both your and the Earth’s lives out of risk.

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