Cracked Heat Exchanger: What That Means and What to Do Next

September 20, 2022

A furnace is almost always a background player at home, helping keep you warm in the cold winter months. It often isn't noticed until a malfunction appears.

One root cause could be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s critical to learn the symptoms of a cracked heat exchanger and what you can do if you are worried that is the problem.

What Is a Heat Exchanger in a Furnace?

A heat exchanger helps transition heat from the combustion chamber inside your furnace to the air that circulates throughout the air ducts. It generally accomplishes this with coils or tubes that warm 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?

Because of its key role, it isn't surprising that a cracked heat exchanger can be hazardous. Cracks in the heat exchanger can permit dangerous gasses – like carbon monoxide, which can be lethal – to flow through your home.

For obvious reasons, do NOT turn on your heater if you believe you're dealing with a cracked heat exchanger, as doing so could make your entire household sick. Contact an HVAC professional right away if you believe your heater has a cracked heat exchanger that needs to be repaired.

Four Warning Signs of a Cracked Heat Exchanger:

  • Furnace shuts off: A cracked heat exchanger could cause your furnace to shut off.
  • Odd Smells: If the air escaping your furnace has a powerful chemical odor, it may be an indicator that gasses are slipping through cracks in your heat exchanger. These byproducts, which can smell like formaldehyde, are a common warning sign.
  • Carbon monoxide alarm goes off or you recognize symptoms of poisoning: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm could go off or household members might experience signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If an alarm goes off or you feel unusually tired, get out of the home immediately and then call for help.
  • Soot: If you notice black sooty buildup near the exterior of your furnace, it’s an indication something may be seriously wrong.

What You Can Do if Your Furnace Heat Exchanger is Cracked

If you suspect your furnace has a cracked heat exchanger, hire a professional with extensive experience in furnace installation Phoenix right away so they can examine your system and, if needed, start a furnace heat exchanger replacement. Costs will vary depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000.

However, the good news is that heat exchangers are generally covered by the warranty. It's a good idea to confirm the warranty paperwork on your furnace, since while the warranty may not cover the entire cost of repairs, it can significantly lower your bill.

How to Prevent a Cracked Heat Exchanger in Your Home

One of the easiest ways to prevent a problem in your furnace overall is via regular furnace maintenance. Furnaces work the best when they work efficiently. Hiring a skilled professional to examine your furnace for broken-down parts, dirty filters and other likely problems can help you avoid getting a big bill later on.

It’s also beneficial to review your furnace filters every few months – it’s recommended 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 dragging air through a clogged filter makes the entire furnace work more vigorously to do its job. And the harder your furnace works, the more strain components like the heat exchanger will experience.