A furnace is usually a background player for your home, helping keep you warm across the cold winter months. It often doesn’t get noticed until something breaks down. 

One cause might be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s important to know the evidence of a cracked heat exchanger and what you can do if you believe 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 circulates inside the ventilation. It typically accomplishes this through coils or tubes that heat up the air while acting as a barrier to keep the gasses produced 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 throughout your home. 

For this reason, don't ever run your furnace if you suspect it has a cracked heat exchanger, as letting it run could make your entire family sick. Contact an HVAC professional immediately if you think your heating has a cracked heat exchanger that should be repaired. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: A crack in your heat exchanger may cause your furnace to turn off. 
  • Strange Smells: If the air coming out of your furnace has a powerful chemical scent, it may be an indicator that gasses are seeping through cracks in your heat exchanger. These byproducts, which may smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm is triggered or you recognize health problems: If a cracked heat exchanger is emitting carbon monoxide inside your home, your carbon monoxide alarm could go off or family members might start experiencing signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If the alarm goes off or you feel sick, get out of the home immediately and then call for help. 
  • Soot: If you spot black sooty buildup around the exterior of your furnace, it’s more evidence something could be seriously wrong.

What You Should Do if Your Furnace Heat Exchanger is Cracked 

If you suspect your furnace has a cracked heat exchanger, hire a pro well versed in furnace installation Ballwin and St. Charles right away so they can inspect your system and, if required, handle a furnace heat exchanger replacement. Costs will differ depending on the situation, but estimates can roughly suggest $1,000 to $3,000. 

Estimates aside, the good news is that heat exchangers are generally protected by the warranty. It's a good idea to check the warranty paperwork on your furnace, because while the warranty might not cover the entire cost of repairs, it can significantly reduce 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 through regular furnace maintenance. Furnaces work the best when they operate efficiently. Contacting a certified professional to examine your furnace for broken-down parts, dirty filters and other common problems can keep you from getting a big bill later on.  

It’s also helpful 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 a part of the heat exchanger itself, the strain of drawing air through a clogged filter makes the entire furnace work harder to accomplish its job. And the harder your furnace has to work, the more wear and tear pieces like the heat exchanger will endure.