A furnace is almost always a background player for your home, helping keep you warm during the cold winter months. It frequently doesn’t get noticed until something goes wrong.
One source might be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s critical to know the symptoms of a cracked heat exchanger and what to do if you believe that might be the problem.
What Is a Heat Exchanger in a Furnace?
A heat exchanger helps move heat from the combustion chamber inside your furnace to the air that flows throughout the air ducts. It usually handles this with coils or tubes that heat the air while serving as a barrier to keep the gasses formed in the combustion chamber, called flue gasses, from escaping out into your home.
Is a Cracked Heat Exchanger Dangerous?
Thanks to its important role, it shouldn't come as a surprise that a broken heat exchanger can be very dangerous. A crack in the heat exchanger can allow dangerous gasses – including carbon monoxide, which can be lethal – to circulate across your home.
For this reason, do NOT run your furnace if you suspect you're dealing with a cracked heat exchanger, as this could make your entire household ill. Contact an HVAC professional right away if you believe your heating has a cracked heat exchanger that needs to be repaired.
Four Signs of a Cracked Heat Exchanger:
- Furnace switches off: Cracks in the heat exchanger can cause your furnace to shut off.
- Unusual Smells: If the air leaving your furnace has a powerful chemical scent, it might be a sign gas is seeping through cracks in your heat exchanger. These byproducts, which will often smell like formaldehyde, are a common warning sign.
- Carbon monoxide alarm goes off 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 could struggle with signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If the alarm goes off or you feel sick, exit the home as soon as you can and then call for help.
- Soot: If you spot black sooty buildup near the exterior of your furnace, it’s another sign something may be seriously wrong.
What to Do if Your Furnace Heat Exchanger is Cracked
If you suspect your furnace has a cracked heat exchanger, contact a pro well versed in furnace installation right away so they can examine your system and, if required, start a furnace heat exchanger replacement. Costs should fluctuate depending on the situation, but estimates often hover around $1,000 to $3,000.
Fortunately, the good news is that heat exchangers are generally covered by the warranty. You’ll want to check the warranty paperwork on your furnace, since while the warranty might not cover the entire cost of repairs, it could significantly shrink 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 offer the most benefits when they operate efficiently. Calling a certified professional to check your furnace for old parts, clogs in the air filters and other likely problems can help you avoid getting a big bill later on.
It’s also a good idea to review your furnace filters every few months – it’s ideal some filters be changed every 90 days or sooner if they are dirty or grimy. While the filters aren't a part of the heat exchanger itself, the strain of pulling air through a clogged filter makes the entire furnace work harder to complete its job. And the harder your furnace needs to run, the more deterioration components like the heat exchanger will endure.