A furnace is usually a background player for your home, ensuring you're warm in the cold winter months. It regularly isn't noticed until something goes wrong. 

One source might be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s worthwhile to know the signs 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 in your furnace to the air that circulates inside the system. It usually handles this using coils or tubes that heat up the air while functioning as a barrier to keep the gasses 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 damaged heat exchanger can be very dangerous. A damaged heat exchanger can allow dangerous gasses – like carbon monoxide, which can be lethal – to circulate throughout your home. 

For that reason, don't ever turn on your furnace if you believe there's a crack in the heat exchanger, as letting it run could make the whole household sick. Call an HVAC professional right away if you think your furnace has a cracked heat exchanger that needs repair. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace shuts off: A cracked heat exchanger could cause your furnace to turn off. 
  • Strange Smells: If the air coming out of your furnace has a strong chemical scent, it might be evidence gas is leaking through cracks in your heat exchanger. These byproducts, which may smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm is triggered or you feel symptoms of poisoning: If a cracked heat exchanger is relieving carbon monoxide into your home, your carbon monoxide alarm may go off or family members might start experiencing signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If your alarm goes off or you feel sick, get out of the home immediately and then call for help. 
  • Soot: If you spot black sooty accumulating near the exterior of your furnace, it’s another sign something could be seriously wrong.

What You Can Do if the Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, call a professional well versed in furnace installation Holbrook as soon as possible so they can examine your system and, if needed, handle a furnace heat exchanger replacement. Costs should differ depending on the situation, but estimates can roughly suggest $1,000 to $3,000. 

Fortunately, the good news is that heat exchangers are often included in the warranty. It's a good idea to confirm the warranty paperwork on your furnace, because while the warranty won't always cover the entire cost of repairs, it can significantly lower your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the best ways to prevent a problem in your furnace overall is via routine furnace maintenance. Furnaces work the best when they work efficiently. Calling a skilled professional to check your furnace for worn-out parts, clogs in the air filters and other potential 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 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 drawing air through a clogged filter makes your entire furnace work harder to do its job. And the harder your furnace works, the more deterioration pieces like the heat exchanger will experience.