What is a Heat Exchanger?

October 11, 2013

The heat exchanger is one of the most important parts of your furnace.  It could also be the most dangerous when something goes wrong.  That’s why it’s so important for our clients to understand the function of a heat exchanger, and how to avoid potential problems.

What Does It Do?

In a gas furnace, the heat exchanger is the first place that combustion gases go after they’ve been produced by the burners.   The heat from the gas is transferred onto the walls of the heat exchanger. Once the heat has been removed, the combustion byproduct gases are expelled to the outdoors through the chimney. If you have a high efficiency furnace (PVC flue pipe), the gases go through a second heat exchanger where even more heat is extracted before the gases are vented out of the home.

While the gases are warming the heat exchanger, the blower motor is moving air over it, picking up the heat and distributing throughout your home.

Why Can They be Dangerous?

Heat exchangers are made out of metal. When metal gets hot, it expands. Then it contracts when cooled.  Over time the metal can weaken and form cracks allowing carbon monoxide from the gas to leak into your home. Another cause of heat exchanger failure is water running down through the furnace from the evaporator coil freezing up or clogged condensate drains.  Water causes premature rust which will also weaken the metal.

Is Your Furnace Safe?

The best way to ensure that your heat exchanger is not leaking carbon monoxide is to have planned maintenance performed every year.  Our technicians can perform a variety of tests to determine if yours is safe to operate.  You should also have carbon monoxide detectors installed near the furnace and by every bedroom.  These detectors should be replaced every 5 years because, unlike a smoke detector, they have sensors that fail over time

Remember, carbon monoxide is a colorless and odorless toxic gas that literally suffocates its victims. It’s something that every person that has a furnace or any gas burning appliance should be aware of.  

We hope you stay safe, as well as warm and cozy this fall!