Furnace Safety 101: Your Heat Exchanger

A gas furnace is a great way to keep your home toasty and warm all through the winter. And natural gas is a great fuel option. But setting anything on fire—and that’s what happens when you combust fuel—comes with risks. Your furnace has some mechanisms in place that keep you safe.

The most important component for the safety and function of your furnace is the heat exchanger. But it requires care to make sure it’s in good enough condition to continue keeping you safe! What is a furnace’s heat exchanger? What can go wrong with it? How can you tell if you need furnace repair in Madison, WI? We’ll explain everything.

What Furnace Combustion Gases Reveal About Heat Exchanger Safety

Just like the internal combustion engine of a vehicle, your furnace burns fuel, and exhaust is created from that process. The exhaust, or combustion gasses, are also where the heat is! But they aren’t safe to breathe. They’re full of carbon monoxide, so they have to be safely vented out of your home. But first, you want to capture that heat!

How Your Furnace Heat Exchanger Transfers Heat Safely

A heat exchanger is an enclosed component that the combustion gasses pass through on their way to the furnace’s ventilation system. It has a ton of surface area, being a strange wavy-shaped component. 

This means that there is hot exhaust inside and fresh air outside, passing against each other with just a layer of metal between. The blower fan pushes air across to soak up as much of that heat as possible, and it’s this air that goes to your ducts and into your home.

Why Heat Exchanger Expansion and Contraction Can Cause Cracks

A heating system works in cycles, heating up to warm your home and then cooling off at the end of the cycle until the thermostat signals that more heat is needed. Thus, the heat exchanger is getting hotter and colder all the time. This leads to constant expansion and contraction, which will eventually put a lot of strain on the metal that the component is made of. This can result in cracking.

Warning Signs of a Cracked Furnace Heat Exchanger

Several things could let you know of a crack in your heat exchanger. A flame that flickers or is any color other than blue, soot or moisture in the furnace cabinet, clicking sounds as the system cools down, unpleasant odors, or, in a severe case, physical symptoms like headaches or your carbon monoxide detector going off.

How to Prevent Dangerous Heat Exchanger Problems

If you suspect you already have a problem with your heat exchanger, you need furnace repair immediately. But it’s also possible to dramatically decrease the risk of this problem, as well as other repair needs and safety concerns. All you need to do is schedule routine maintenance every single year. Many problems can be prevented, or at least caught early, before they become dangerous.

Do you need furnace maintenance or repair? Don’t put it off. Make that appointment today.

Frequently Asked Questions

Question: What does a furnace heat exchanger do?
Answer: A furnace heat exchanger captures heat from combustion gases and transfers it to the clean air that circulates through your home. The combustion gases stay inside the exchanger and are vented outdoors, while the blower moves warmed air across the metal surface and into your ductwork.

Question: Why is a cracked heat exchanger dangerous?
Answer: A cracked heat exchanger can allow combustion gases to escape where they should not. Those gases may contain carbon monoxide, which is unsafe to breathe and difficult to detect without an alarm. That is why any suspected crack should be treated as an urgent furnace safety concern.

Question: What are the signs of a cracked furnace heat exchanger?
Answer: Warning signs can include a flickering flame, a flame that is not blue, soot or moisture inside the furnace cabinet, clicking sounds as the system cools, unpleasant odors, headaches, or a carbon monoxide detector sounding. These symptoms should be checked by a furnace repair professional.

Question: What causes a furnace heat exchanger to crack?
Answer: Heat exchangers repeatedly heat up and cool down during normal furnace cycles. This constant expansion and contraction puts stress on the metal over time. Without regular maintenance, that stress can contribute to cracks, especially if other furnace issues are causing extra strain on the system.

Question: How can homeowners help prevent heat exchanger problems?
Answer: The best prevention step is scheduling furnace maintenance every year. Routine service gives a technician a chance to inspect key safety components, catch small problems early, and reduce the risk of dangerous furnace issues. It also helps keep the heating system running safely and reliably through winter.

You can always count on 24-Hour Home Comfort Services, your heating and cooling specialists.