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

One root cause may be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s important to know the evidence 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 of your furnace to the air that moves inside the ventilation. It usually handles this with coils or tubes that heat the air while functioning as a barrier to keep byproducts created in the combustion chamber, called flue gasses, from getting out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Thanks to its key role, it’s no surprise that a damaged heat exchanger can be very dangerous. A crack in the heat exchanger can enable dangerous gasses – including carbon monoxide, which can be lethal – to be distributed throughout your home. 

For that reason, never use your furnace if you suspect you're dealing with a cracked heat exchanger, as this could make the entire household sick. Contact an HVAC professional immediately if you are worried your heating has a cracked heat exchanger that needs repair. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: A cracked heat exchanger can cause your furnace to shut off. 
  • Strange Smells: If the air coming out of your furnace has a strong chemical smell, it could be evidence gas is seeping through cracks in your heat exchanger. These gasses, which may smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm initiates or you feel health problems: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm should go off or household members could struggle with signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If the alarm goes off or you feel sick, exit the home immediately and then call for help. 
  • Soot: If you find black sooty collecting near the exterior of your furnace, it’s an indication something may be seriously wrong.

What You Should Do if Your Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, call a professional with extensive experience in furnace installation Swanton right away so they can examine your system and, if necessary, perform a furnace heat exchanger replacement. Costs should differ depending on the situation, but estimates often hover around $1,000 to $3,000. 

Fortunately, the good news is that heat exchangers are generally protected by the warranty. You’ll want to check the warranty paperwork on your furnace, as while the warranty won't always cover the entire cost of repairs, it could significantly lower your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the most convenient ways to prevent a problem in your furnace overall is through consistent furnace maintenance. Furnaces offer the most benefits when they work efficiently. Contacting a certified professional to inspect 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 a good idea to review your furnace filters every few months – it’s recommended some filters be replaced 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 needs to run, the more strain pieces like the heat exchanger will sustain.