What Is A Heat Exchanger, And Why Might It Need Repairs?

As someone who is not an HVAC contractor, you probably don't know a lot about the various parts of a furnace. And that's okay! Understanding furnaces is not your profession. However, there is one key furnace part that's worth knowing about as a homeowner: the heat exchanger. Heat exchanger problems can be dangerous, so it's a good idea to know the basics about this part and its repair. 

What is the heat exchanger?

The heat exchanger is a big piece of metal or ceramic that surrounds the fire in your furnace. The heat exchanger gets hot, and it then passes that heat onto the air passing through the furnace. The heat exchanger basically creates a barrier between the flame and the air pushed through your system. As such, it prevents any gases produced by the flame, such as carbon monoxide, from getting pushed into your home.

How do heat exchangers break?

Sometimes heat exchangers crack. This can happen simply because the furnace is old, or it may be the eventual result of having a dirty air filter. Pressure builds up in the furnace when the air filter is clogged, and this pressure can crack the heat exchanger.

How do you know your heat exchanger is broken?

Often, the first sign of a broken heat exchanger is a "boom" noise when the furnace kicks on. You'll notice this sound each time the flame is lit. Over time, the sound might get louder and louder.

Another key sign is the buildup of soot in and around the furnace. The presence of soot means your furnace is not burning as hot as it should, which can be caused by a broken heat exchanger. 

Finally, your CO detector may go off if you have a broken heat exchanger. This means CO is escaping through the crack in the component. If this happens, turn your furnace off and get out of the house until you can have repairs made.

How are heat exchangers repaired?

Sometimes, an HVAC technician can repair a heat exchanger by filling in the crack with some weld or epoxy. Other times, they may opt to simply replace the heat exchanger. Neither of these repairs takes too long, so your HVAC contractor should be finished within a day.

If your furnace is older and has other issues, your HVAC contractor may recommend replacing the whole unit rather than just the heat exchanger.

Now that you know a bit more about heat exchangers, you're better prepared to live safely in a home with a furnace.

Contact a local HVAC service to learn more about heater repair.