A furnace is usually a background player in your home, ensuring you're warm in the cold winter months. It often won't be noticed until a malfunction appears. 

One cause could be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s important to familiarize yourself with the evidence of a cracked heat exchanger and what you should do if you suspect that may be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger transfers heat from the combustion chamber of your furnace to the air that moves inside the ventilation. It generally does this through coils or tubes that heat the air while acting as a barrier to keep the gasses created in the combustion chamber, called flue gasses, from getting out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Given its important role, it shouldn't come as a surprise that a damaged heat exchanger can be very dangerous. Cracks in the heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to be distributed through your home. 

For obvious reasons, never use your heater if you suspect you're dealing with a cracked heat exchanger, as this could make the entire household sick. Call an HVAC professional as soon as possible if you are worried your furnace has a cracked heat exchanger that should be repaired. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: Cracks in the heat exchanger may cause your furnace to switch off. 
  • Strange Smells: If the air leaving your furnace has a strong chemical scent, it may be an indicator that gasses are leaking 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 relieving carbon monoxide into your home, your carbon monoxide alarm could go off or household members may start experiencing signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If your alarm goes off or you feel sick, leave the home immediately and then call for help. 
  • Soot: If you spot black sooty collecting on the exterior of your furnace, it’s more evidence something might be seriously wrong.

What to Do if the Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, call a pro well versed in furnace installation Hodgenville as soon as possible so they can inspect your system and, if required, perform a furnace heat exchanger replacement. Costs often vary depending on the situation, but estimates can roughly suggest $1,000 to $3,000. 

Estimates aside, the good news is that heat exchangers are regularly covered by the warranty. You’ll want to review the warranty paperwork on your furnace, because while the warranty may not cover the entire cost of repairs, it can significantly reduce your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the easiest ways to prevent a problem in your furnace overall is with routine furnace maintenance. Furnaces offer the most benefits when they work efficiently. Contacting a certified professional to check your furnace for worn-out parts, clogs in the air filters and other potential problems can help you avoid getting a big bill later on.  

It’s also helpful to take a look at your furnace filters every few months – it’s ideal some filters be changed 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 pulling air through a clogged filter makes your entire furnace work harder to accomplish its job. And the harder your furnace works, the more strain pieces like the heat exchanger will endure.