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Serving the Greater New Braunfels, TX Area

Serving the Greater New Braunfels, TX Area


Why Are Cracked Heat Exchangers Serious Problems for Gas Furnaces?


You may have heard about “cracked heat exchangers” in gas furnaces as one of the major problems these heating systems can have. What does this mean, and how can you protect yourself from it? Below, we’ll look into the problem of a cracked heat exchanger.

The Heat Exchanger Itself

You may not know what a heat exchanger is to begin with, so we’ll start there. The heat exchanger is the component in a gas furnace that does the direct heating of the air that moves into the ductwork. The heat from the gas burners can’t come into direct contact with the air because of the combustion gas, so the heat exchanger serves as the intermediate step. The hot combustion gas from the burners collects inside the metal chambers of the heat exchanger and raises the temperature of the metal. The blower then sends air around the exchanger and the heat transfers from the metal surface to the air. Once the heating cycle is complete, the remaining combustion gas in the exchanger exits the furnace and the house through a flue.

The Cracked Heat Exchanger

Since the purpose of the heat exchanger is to prevent toxic combustion gas from coming in contact with the air going into the house, cracks in the exchanger create a significant safety hazard. Even a small crack on the exchanger can become a source of gas leaking into the air because the metal of the exchanger expands as it heats up, causing any cracks to stretch open. Cracked heat exchangers are one of the leading causes of toxic carbon monoxide gas escaping from a furnace and into the air of a home.

The Cause of Cracked Heat Exchangers

The main cause of cracks forming along a heat exchanger is corrosion weakening the metal. Since heat exchangers constantly expand and contract over the years, any weakness from corrosion can quickly lead to cracks forming. Corrosion can start along the heat exchanger because of the chemical reaction between the combustion vapor inside and the metal of the exchanger. This process can affect extremely old furnaces, but poor venting through the flue can speed it up.

Preventing Cracked Heat Exchangers

The best tool against this problem is to always arrange for professional maintenance for your furnace each year, preferably in the fall. We often talk about the many benefits of maintenance, but safety is arguably the biggest one. During maintenance for a gas furnace, our technicians will carefully check the heat exchanger for signs of either cracks or developing corrosion. We also test the venting to ensure it’s working properly. Combustion analysis tests can also tell us if any carbon monoxide is escaping from the furnace. If we do find problems, we can arrange for repairs or (often the case with older furnaces) a replacement furnace.

To help protect yourself from a cracked heat exchanger in New Braunfels, TX, make sure that you have working carbon monoxide detectors in your home. Test them every six months to see that they have power. These detectors will warn you if CO levels start to rise in your house so you can vacate and call the gas company. 

At Thayer Air Conditioning, your comfort is our #1 priority! Depend on us to service your furnace and keep your home safe and warm.

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