Understanding Heat Exchangers and How They Work

December 20, 2021
Heat Exchanger in Fieldale, VA

A heat exchanger is vital to the proper functioning of your furnace. Unfortunately, many homeowners only learn about the heat exchanger when something goes wrong with the furnace. This post explores what a heat exchanger is and how it works.

What Is a Heat Exchanger?

A heat exchanger is a thin metal shield that’s located inside your furnace. It has two key functions:

  • Exchanges heat: First, it transfers heat from your furnace via air ducts into the living spaces of your home.
  • Aids in combustion: Then, it helps prevent incomplete combustion that can cause your furnace to produce high levels of poisonous gases.

Basically, a heat exchanger allows for the safe transfer of heated air throughout the living spaces in your home.

How Does a Heat Exchanger Work?

It works by transferring the heat produced in the combustion chamber to the unit’s exterior, where it is then distributed through the air ducts to the living spaces in the home. Typically, the process takes three steps:

  • First, combustion begins when the furnace is turned on. Hot combustion gases enter and travel through the heat exchanger, heating its metal walls.
  • Next, the furnace’s air handler takes in cold air from inside the home and begins to blow it over the heat exchanger’s exterior walls. The air is warmed as it blows over the exchanger’s heated walls before being sent back through the air ducts to various areas in the home. During this process, combustion gases and breathing air don’t mix.
  • Finally, the gases produced during combustion are blown out of the heat exchanger and sent outside the home via a vent.

Generally, most furnaces follow the three-step process above. However, condensing furnaces work slightly differently. In condenser furnaces, the gases are passed through another heat exchanger that draws extra heat for home use.

Ultimately, a properly working heat exchanger is crucial to your safety. Ensure you schedule routine furnace maintenance at least once annually. During a furnace inspection, the HVAC professional will check your heat exchanger for any signs of cracks or other problems that could arise in the future.

If your furnace isn’t performing at its optimal level, we can help you detect and solve the underlying problem. At McKinney Heating & Air Conditioning, we’ve been helping residents of Martinsville, Fieldale, and the surrounding areas keep their HVAC systems in tip-top condition since 1972. We also offer tankless water heaters and indoor air quality services. Contact us today to schedule an appointment or to learn more about our services.

company icon