The heat exchanger is one of the most essential parts of your furnace. This part is the link between combustion and creating the heated air that gets blown into your living spaces.

What is a heat exchanger?

Your furnace's heat exchanger allows the air from the cool air return to get close enough to the natural gas, electric, or fuel oil-powered combustion to heat that air before it is recirculated throughout your home. Without the exchanger, you have cool air and you have a controlled fire, but the two won't get together to form heated air.

Things that can cause your heat exchanger to fail

Unlike many furnace problems, a cracked heat exchanger won't generally stop your furnace from working. However, this is a problem that needs to be addressed right away. Not only will your furnace work less efficiently with a cracked exchanger, using more energy and energy dollars, but dangerous combustion gases like CO2 can escape via the exchanger, putting your family and home at risk.

The average stainless steel heat exchanger has a lifespan of around 15–20 years.  However, there are several furnace issues that take their toll on your heat exchanger. Help to prevent these and your heat exchanger will last much longer.

  1. Short cycling. When your furnace cuts in and out repeatedly without heating your rooms sufficiently (called short cycling in the HVAC community), it puts a lot of stress on the heat exchanger. This metal part barely cools down and its asks to heat up again, a process that can wear out the metal over time.
  2. Poor maintenance. A dusty, dirty air filter inhibits good air flow within the furnace and can cause your heat exchanger to get hotter than necessary, again weakening the metal. It's a good idea to change your air filter at least once a month during the cold weather season to prevent this scenario.
  3. Restricted air flow. The air flow to and from your furnace can also be affected by duct work that has become detached, closed vents and registers that are blocked by furniture and other objects. Any of these issues can cause the exchanger to overheat, shortening its lifespan and/or causing it to crack.

If you suspect that you have an issue with your furnace's heat exchanger, it's time to call a heating professional like All Heating Services. This type of repair is beyond the scope of a DIY homeowner.