A furnace is often a background player at home, helping keep you warm across the cold winter months. It often isn't noticed until a malfunction appears.
One cause may be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s critical to know the evidence of a cracked heat exchanger and what you can do if you are worried that may be the problem.
What Is a Heat Exchanger in a Furnace?
A heat exchanger transfers heat from the combustion chamber in your furnace to the air that circulates inside the system. It generally accomplishes this using coils or tubes that warm the air while serving as a barrier to keep gas produced in the combustion chamber, called flue gasses, from leaking out into your home.
Is a Cracked Heat Exchanger Dangerous?
Given its key role, it’s no surprise that a damaged heat exchanger can be very dangerous. A crack in the heat exchanger can allow dangerous gasses – including carbon monoxide, which can be lethal – to flow throughout your home.
For that reason, do NOT run your heating if you suspect you're dealing with a cracked heat exchanger, as letting it run could make the entire household sick. Contact an HVAC professional right away if you think your heating has a cracked heat exchanger that needs to be repaired.
Four Symptoms of a Cracked Heat Exchanger:
- Furnace turns off: A cracked heat exchanger could cause your furnace to switch off.
- Strange Smells: If the air leaving your furnace has a strong chemical odor, it might be a sign gasses are seeping through cracks in your heat exchanger. These gasses, which will often smell like formaldehyde, are a significant warning sign.
- Carbon monoxide alarm initiates or you recognize symptoms of poisoning: If a cracked heat exchanger is relieving carbon monoxide into your home, your carbon monoxide alarm should go off or household members could start experiencing signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If the alarm goes off or you feel sick, leave the home as soon as you can and then call for help.
- Soot: If you spot black sooty accumulating near the exterior of your furnace, it’s another sign something might be seriously wrong.
What You Should Do if the Furnace Heat Exchanger is Cracked
If you believe your furnace has a cracked heat exchanger, call a professional experienced in furnace installation as soon as possible so they can take a look at your system and, if needed, handle a furnace heat exchanger replacement. Costs will differ 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 regularly protected by the warranty. It's a good idea to review the warranty paperwork on your furnace, as while the warranty won't always cover the entire cost of repairs, it can significantly lower your bill.
How to Avoid a Cracked Heat Exchanger in Your Home
One of the easiest ways to minimize the risk of problems in your furnace overall is via routine furnace maintenance. Furnaces work the best when they operate efficiently. Contacting a certified professional to check your furnace for worn-out parts, clogged filters and other potential problems can keep you from getting a big bill later on.
It’s also helpful to take a look at your furnace filters every few months – it’s ideal some filters be swapped out 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 drawing air through a clogged filter makes the entire furnace work longer to do its job. And the harder your furnace works, the more wear and tear pieces like the heat exchanger will experience.