A furnace is almost always a background player for your home, keeping you warm in the cold winter months. It often isn't noticed until a malfunction appears.
One root cause might be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s worthwhile to familiarize yourself with the signs of a cracked heat exchanger and what you can do if you believe that may be the problem.
What Is a Heat Exchanger in a Furnace?
A heat exchanger transfers heat from the combustion chamber inside your furnace to the air that moves through the system. It typically handles this through coils or tubes that heat the air while functioning as a barrier to keep the gasses produced in the combustion chamber, called flue gasses, from escaping out into your home.
Is a Cracked Heat Exchanger Dangerous?
Given its key role, it shouldn't come as a surprise that a cracked heat exchanger can be very dangerous. A crack in the heat exchanger can permit dangerous gasses – like carbon monoxide, which can be lethal – to flow through your home.
For this reason, don't ever run your heating if you suspect you're dealing with a cracked heat exchanger, as this could make your entire household sick. Contact an HVAC professional immediately if you believe your furnace has a cracked heat exchanger that needs to be repaired.
Four Symptoms of a Cracked Heat Exchanger:
- Furnace turns off: A crack in your heat exchanger could cause your furnace to switch off.
- Odd Smells: If the air leaving your furnace has a powerful chemical smell, it may be evidence gas is slipping through cracks in your heat exchanger. These byproducts, which can smell like formaldehyde, are a major warning sign.
- Carbon monoxide alarm is triggered or you notice health problems: If a cracked heat exchanger is emitting carbon monoxide inside your home, your carbon monoxide alarm may go off or household members might experience signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If the alarm goes off or you feel unusually tired, exit the home right away and then call for help.
- Soot: If you see black sooty buildup near the exterior of your furnace, it’s another sign something might be seriously wrong.
What to Do if a Furnace Heat Exchanger is Cracked
If you suspect your furnace has a cracked heat exchanger, call a pro with extensive experience in furnace installation right away so they can inspect your system and, if required, perform a furnace heat exchanger replacement. Costs often vary depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000.
Fortunately, the good news is that heat exchangers are generally included in the warranty. You should check the warranty paperwork on your furnace, since while the warranty may not cover the entire cost of repairs, it could significantly reduce your bill.
How to Prevent a Cracked Heat Exchanger in Your Home
One of the easiest ways to avoid problems in your furnace overall is through consistent furnace maintenance. Furnaces work the best when they operate efficiently. Contacting a certified professional to check your furnace for old parts, clogged filters and other potential problems can keep you from getting a big bill later on.
It’s also helpful to inspect your furnace filters every few months – it’s encouraged some filters be changed every 90 days or sooner if they are dirty or grimy. While the filters aren't connected to the heat exchanger itself, the strain of pulling air through a clogged filter makes your entire furnace work more vigorously to do its job. And the harder your furnace has to work, the more wear and tear parts like the heat exchanger will sustain.