A furnace is almost always a background player for your home, ensuring you're warm in 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’s a potentially dangerous issue, so it’s critical to learn 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 transition heat from the combustion chamber in your furnace to the air that flows inside the system. It usually handles this via coils or tubes that heat up the air while serving as a barrier to keep gas created in the combustion chamber, called flue gasses, from escaping 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 hazardous. A damaged heat exchanger can allow dangerous gasses – such as carbon monoxide, which can be lethal – to be distributed across your home. 

For obvious reasons, don't ever use your furnace if you suspect there's a crack in the heat exchanger, as letting it run could make the whole family ill. Reach out to an HVAC professional right away if you are worried your heating has a cracked heat exchanger that needs repair. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace turns off: A crack in your heat exchanger can cause your furnace to turn off. 
  • Strange Smells: If the air leaving your furnace has a powerful chemical smell, it could be a sign gasses are leaking through cracks in your heat exchanger. These byproducts, which will often smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm is triggered or you notice symptoms of poisoning: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm could go off or household members might struggle with signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If the alarm goes off or you feel sick, get out of the home right away and then call for help. 
  • Soot: If you notice black sooty accumulating around the exterior of your furnace, it’s more evidence something may be seriously wrong.

What You Can Do if Your Furnace Heat Exchanger is Cracked 

If you worry your furnace has a cracked heat exchanger, contact a pro with extensive experience in furnace installation Lexington right away so they can take a look at your system and, if needed, perform a furnace heat exchanger replacement. Costs often differ depending on the situation, but estimates often hover around $1,000 to $3,000. 

However, the good news is that heat exchangers are generally covered by the warranty. It's a good idea to confirm the warranty paperwork on your furnace, because while the warranty might not 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 easiest ways to avoid problems in your furnace overall is via regular furnace maintenance. Furnaces provide the best possible return on investment when they work efficiently. Hiring a certified professional to inspect your furnace for worn-out parts, clogged 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 encouraged some filters be changed 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 dragging air through a clogged filter makes your entire furnace work more vigorously to do its job. And the harder your furnace works, the more wear and tear pieces like the heat exchanger will sustain.