A furnace is usually a background player at home, helping keep you warm across the cold winter months. It often won't be noticed until something goes wrong. 

One cause may be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s important to know the signs of a cracked heat exchanger and what to do if you are worried that may be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger helps transition heat from the combustion chamber of your furnace to the air that flows inside the air ducts. It generally does this via coils or tubes that heat the air while serving 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? 

Thanks to its central role, it isn't surprising that a damaged heat exchanger can be very dangerous. A crack in the heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to be distributed through your home. 

For that reason, don't ever run your heater if you believe it has a cracked heat exchanger, as this could make the whole family sick. Contact an HVAC professional right away if you are worried your heater has a cracked heat exchanger that should be repaired. 

Four Symptoms of a Cracked Heat Exchanger: 

  • Furnace switches off: A crack in your heat exchanger can cause your furnace to turn off. 
  • Unusual Smells: If the air coming out of your furnace has a powerful chemical smell, it may be evidence gasses are seeping through cracks in your heat exchanger. These byproducts, which can smell like formaldehyde, are a major warning sign. 
  • Carbon monoxide alarm goes off or you feel symptoms of poisoning: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm should go off or household members may start experiencing signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If an alarm goes off or you feel unusually tired, get out of the home as soon as you can and then call for help. 
  • Soot: If you spot black sooty collecting on the exterior of your furnace, it’s an indication something could be seriously wrong.

What You Can Do if a Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, contact a pro well versed in furnace installation Fredericksburg as soon as possible so they can inspect your system and, if required, perform 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 included in the warranty. You should confirm the warranty paperwork on your furnace, as while the warranty won't always 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 provide the best possible return on investment when they work efficiently. Contacting a certified professional to inspect your furnace for broken-down parts, clogged filters and other common 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 replaced 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 longer to accomplish its job. And the harder your furnace needs to run, the more strain pieces like the heat exchanger will sustain.