A furnace is often a background player in your home, helping keep you warm in the cold winter months. It frequently isn't noticed until something goes wrong. 

One cause may be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s important to learn the symptoms of a cracked heat exchanger and what you should do if you believe that may 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 inside the ventilation. It generally accomplishes this with coils or tubes that heat the air while functioning as a barrier to keep byproducts formed in the combustion chamber, called flue gasses, from getting out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Because of its important role, it shouldn't come as a surprise that a cracked heat exchanger can pose a risk. Cracks in the heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to flow through your home. 

For this reason, don't ever turn on your heater if you think it has a cracked heat exchanger, as letting it run could make the entire household ill. Call an HVAC professional immediately if you are worried 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 can cause your furnace to shut off. 
  • Strange Smells: If the air escaping your furnace has an intense chemical smell, it could be a sign gasses are seeping through cracks in your heat exchanger. These gasses, which will often 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 emitting carbon monoxide inside your home, your carbon monoxide alarm should go off or household members may experience signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If your alarm goes off or you feel unusually tired, get out of the home immediately and then call for help. 
  • Soot: If you spot black sooty accumulating on 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, hire a pro with extensive experience in furnace installation Wisconsin Rapids right away so they can inspect your system and, if needed, 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. 

Estimates aside, the good news is that heat exchangers are often protected by the warranty. It's a good idea to review the warranty paperwork on your furnace, because while the warranty may 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 minimize the risk of problems in your furnace overall is via regular furnace maintenance. Furnaces work the best when they operate efficiently. Hiring a certified professional to inspect your furnace for worn-out parts, clogged filters and other likely problems can help you avoid getting a big bill later on.  

It’s also beneficial to take a look at your furnace filters every few months – it’s encouraged some filters be replaced every 90 days or sooner if they are dirty or grimy. While the filters are not part of the heat exchanger itself, the strain of dragging air through a clogged filter makes your entire furnace work harder to do its job. And the harder your furnace needs to run, the more deterioration components like the heat exchanger will sustain.