B&E Air and Heat

In the last article we wrote about the Dangers of a Cracked Heat Exchanger, and showed a short video of what a bad heat exchanger looks like in a furnace that was removed from a home. In this article, we want to share some of the reasons they may get cracked in the first place.

Why Do Heat Exchangers Crack?

Cracks in metal surfaces are caused by stress and flexing of the metal. Each time your furnace heats up and cools down, this cycle will naturally cause the metal surfaces to contract and expand, applying more stress to the metal and ultimately resulting in a crack or failure of the heat exchanger. This is a natural process that happens to every furnace over time and the rate at which it happens to yours, just depends on how the unit is maintained, and the quality of your installation.

If you have ever owned a gas grill, you have seen the cracks that develop around the edges of the metal burner surface. These are very similar to heat exchanger cracks, in the way the metal burner goes through many heating and cooling cycles, eventually developing small hairline cracks. Over longer periods of time, those small cracks eventually turn into bigger cracks.

Premature Cracks in the Heat Exchanger

As previously mentioned, natural expansion and contraction of the metal surfaces will create cracks in the heat exchanger over several years of normal operation. Premature cracks however, can also occur very early in the life of your furnace without proper maintenance or an improper installation.

Common Causes of Premature Heat Exchanger Cracks

• Improper Air Flow
  Dirty filters, closed off vents and furniture blocking return vents can contribute to improper air flow to your unit, causing the the system to work harder than it was designed!
• Improper Combustion of Gases
  Hand in hand with the airflow restrictions, when your burners are not firing properly, they can run hotter, or at lower efficiency than the unit is designed to work.
• Improper Displacement of Condensation
  Most common in furnaces that have not been run (heat or cool) in a long time, condensation accumulates in the heat exchanger, eventually rusting out the system.

The life of a heat exchanger is about 20 years with regular gas furnace maintenance.  Gas packs, or Gas Package Units, are known to wear out faster than other units, since they are exposed to the weather and susceptible to the heating, cooling and most importantly, condensation cycle more often.

In the current heating season of 2009-2010, roughly 65% of all cracked heat exchangers we have replaced were on gas packs, less than 10 years old!

Do You Have a Cracked Heat Exchanger?

In most cases, the heat exchanger repair is simply not worth the cost on a furnace more than 8-10 years old! Other parts may have been exposed to the same conditions that caused the heat exchanger to fail, and you end up in a cycle of repairing several parts within a short time frame.

Call us or request a repair quote today – we are always happy to provide a second opinion, and recommend what we feel is best for your specific situation.

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