Fanning The Flames—How Inefficient Combustion Harms Your Furnace

Posted on: 3 March 2023

If you use a natural gas stove, you've probably noticed that the flames typically burn a bright and clear blue. However, you may occasionally notice smaller red flames sparking from the burners. These red flames usually occur when an old piece of food, some grease, or something else ignites on the burner, creating an impurity that doesn't burn as hot as a perfect mixture of gas and oxygen. 

The flames inside your gas furnace are no different. Under ideal circumstances, each burner in your furnace should produce a clear, bright blue flame. Your furnace may even include a sight glass so you can observe the burners. But what does it mean if your burners produce less consistent red or yellow flames, and how concerned should you be? Keep reading to find out.

Understanding Stoichiometric Ratios

When you burn fuel in your furnace, you aim to attain complete combustion. In other words, you want to burn 100% of the fuel that enters the furnace. Achieving this goal means mixing fuel with oxygen in an amount known as a stoichiometric ratio. For natural gas, the stoichiometric ratio is about a 10 to 1 mixture of air to fuel.

While having a little more oxygen is okay, mixtures that are too far off from the stoichiometric ratio can create problems. These ratios will result in inefficient burns, producing less energy for the fuel used. You'll also generate more harmful waste products, making your furnace less environmentally friendly and potentially more dangerous.

Impurities in the mixture, often caused by rust, dust, or debris on the burners, can also result in an inefficient burn. These impurities typically result in an inconsistent red or yellow flame instead of a bright blue one. You may also notice the flame attempting to escape from the combustion chambers, although this situation will usually trigger the roll-out sensors and shut the furnace down.

Recognizing the Dangers of Inefficient Burns

Inefficient combustion is more than just a problem for your monthly utility bills. While inefficiencies will ultimately cost you money by forcing you to use more fuel to heat your home, the added expense is rarely the biggest problem. At best, an inefficient burn will produce more soot and ash that can cause damage to your furnace. At worst, it can release harmful gases into your home.

There are numerous reasons why your furnace may burn inefficiently, from poorly maintained burners to improperly adjusted gas valves. Other potential issues include clogged air intakes, obstructions in the furnace's exhaust flue, or even cracks in the heat exchanger. Any of these problems can be potentially serious and will eventually stop your furnace from running.

If your fuel costs seem to be rising, or you've spotted the telltale signs of an inefficient burn by observing your burners through your furnace's sight glass, it's time to contact a professional. An HVAC technician can analyze your furnace's combustion ratio and help you repair any issues that may compromise your heating system's safety or efficiency.

Contact a local HVAC service, such as American Air Heating & Air Conditioning, to learn more. 


update that old heating system

How long have you been putting off replacing your heating system in your home? Do you worry that the cost of the new system will cost you too much? Have you thought about how much you are losing by not replacing that old furnace? This blog will help you understand how making an investment on a new heating system for your home can actually save you a lot more over the next ten years than you spend on the system and the installation work. Hopefully, by the time you are done reading, you will know what you have to do and why you shouldn't put it off any longer.

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