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AW Heating & Cooling Blog

Don’t Let Your Furnace Suffer from This Dangerous Problem


If you’re like most homeowners in our area, you use a furnace heating system to keep your living space warm during the winter. Gas-powered furnaces are the most popular type of residential heating system across the country, after all.

They not only produce a large amount of heat, but they do so at less expense than electric furnaces because natural gas costs less than electricity per unit.

However, natural gas appliances do come with a risk. That’s not to say they’re inherently dangerous. But if you skip maintenance or don’t keep up on small repair needs, problems can grow and you can end up with a dangerous situation on your hands. One of these possible situations is a cracked heat exchanger.

What Is a Heat Exchanger?

This component is what enables your furnace to heat up the air that travels through the ductwork of your heating system. When the burners of your furnace ignite, they generate hot combustion gas, which is collected inside the heat exchanger—a metal chamber or series of chambers. Most of them have a clam-shell shape.

The hot combustion gas in the heat exchanger heats up the metal walls, and the blower fan of the furnace comes on and sends air around the heat exchanger, where it picks up the heat from the furnace wall and continues through the ducts.

Once the heating process is complete, the combustion byproducts in the heat exchanger are vented out of the system through a flue, to release gas harmlessly into the air outside.

A Cracked Heat Exchanger

Since the metal of the heat exchanger expands and then contracts as it heats and cools, the stress can eventually cause a crack to form on the exchanger. Corrosion due to the reaction between the combustion gas and the metal—usually due to improper venting or even old age—can also weaken the metal to the point where cracks form.

These cracks can be small, but as the exchanger expands with the heat, cracks can open enough to allow some of the combustion gasses to escape and enter your living space. This means these harmful gasses will be sent through the house.

How Do You Know If You Have a Cracked Heat Exchanger?

How can you tell if your heat exchanger is cracked? A major warning sign is if you hear a clicking sound from the furnace soon after the blower shuts off. This should always be investigated.

Also, if you see corrosion anywhere on your furnace, this is also the sign of a problem, and you should probably have the furnace replaced at this point if it’s over 15 years old.

If your CO (carbon monoxide) alarms go off, you should exit the home and call for emergency services. You’ll want to have an HVAC professional check on your furnace system once the initial danger is past. It will likely benefit you to upgrade the system at this point, so please don’t hesitate to ask us about your options!

Contact “Your Comfort Specialists” at AW Heating & Cooling today for expert furnace repair in Toledo, OH.

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