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What are the Causes of a Cracked Heat Exchanger in a Gas Furnace?

small_3149068865A cracked heat exchanger is not a problem that should be taken lightly. If a crack makes its way through the walls of your heat exchanger, dangerous carbon monoxide fumes can leak into your home’s air. One of the best ways you can protect your home from the dangers of a cracked heat exchanger is to know how those cracks develop in the first place.

5 common causes of a cracked heat exchanger

  1. Years of normal wear and tear. Believe it or not, cracks can develop in most furnaces after years of normal use. Heat exchangers are made of metal that expands and contracts every time your furnace turns on and off. Over time, this stress creates cracks in your heat exchanger. If you keep your furnace well maintained throughout its lifetime, you can significantly prolong the amount of time it takes for those cracks to develop. If your furnace is poorly maintained or installed improperly, heat exchanger cracks can develop much quicker.
  2. Poor airflow. Dirty air filters and closed or blocked air registers are a few examples of problems that can slow airflow to your heating system. If your furnace isn’t receiving proper airflow, it can overheat and put extra stress on your heat exchanger. This extra stress often leads to premature cracks.
  3. Incomplete combustion. Airflow issues can also cause combustion problems in your furnace. If your gas furnace is operating with an incomplete combustion process, your burners will have to run hotter and longer. This excess heat puts more stress on your heat exchanger, which leads to cracking.
  4. Oversized furnace. If your furnace wasn’t sized correctly when it was initially installed (a problem that is all too common in St. Louis area homes), your heat exchanger will likely develop premature cracks. If your furnace is oversized, for example, it will go through frequent on-and-off cycles and cause your heat exchanger to expand and contract too often. Another problem associated with an oversized furnace is condensation. In a correctly sized furnace, condensation builds up inside your heat exchanger when your furnace first turns on. This condensation eventually evaporates after a few minutes of use. In an oversized furnace, however, that condensation doesn’t have enough time to evaporate. This condensation can eventually rust out the walls of your heat exchanger.
  5. Undersized furnace. If your furnace is too small for your home, it will have airflow problems and frequently overheat. Overheating will cause your heat exchanger to crack much quicker than it would if your furnace was sized correctly for your home.

If you have any questions about a cracked heat exchanger in your gas furnace, or if you’d like an HVAC system serviced or installed in your home, contact Jerry Kelly, your St. Charles, MO, heating and air conditioning company. We service the St. Louis area and surrounding towns like Clarkson Valley, Ladue and St. Peters.

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