A furnace is often a background player for your home, helping keep you warm across the cold winter months. It regularly won't be 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 familiarize yourself with the symptoms of a cracked heat exchanger and what you should do if you believe that is the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger transfers heat from the combustion chamber inside your furnace to the air that flows throughout the ventilation. It typically does this using coils or tubes that warm the air while serving as a barrier to keep gas formed in the combustion chamber, called flue gasses, from getting out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Given its important role, it isn't surprising that a cracked heat exchanger can be hazardous. A damaged heat exchanger can enable dangerous gasses – like carbon monoxide, which can be lethal – to flow throughout your home. 

For obvious reasons, never turn on your furnace if you believe there's a crack in the heat exchanger, as doing so could make the whole family ill. Call an HVAC professional as soon as possible if you believe your heater has a cracked heat exchanger that needs repair. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace turns off: A cracked heat exchanger may cause your furnace to shut off. 
  • Unusual Smells: If the air leaving your furnace has an intense chemical odor, it may be an indicator that gasses are seeping through cracks in your heat exchanger. These gasses, which may smell like formaldehyde, are a major warning sign. 
  • Carbon monoxide alarm goes off or you feel health problems: If a cracked heat exchanger is emitting carbon monoxide into your home, your carbon monoxide alarm should go off or family members might experience signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If your alarm goes off or you feel unwell, exit the home right away and then call for help. 
  • Soot: If you see black sooty buildup on the exterior of your furnace, it’s an indication something might be seriously wrong.

What You Can Do if Your Furnace Heat Exchanger is Cracked 

If you suspect your furnace has a cracked heat exchanger, call a pro well versed in furnace installation Laurel right away so they can examine your system and, if required, start a furnace heat exchanger replacement. Costs should vary depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000. 

Fortunately, the good news is that heat exchangers are often covered by 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 still may significantly reduce your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the best ways to minimize the risk of problems in your furnace overall is with regular furnace maintenance. Furnaces provide the best possible return on investment when they work efficiently. Hiring a skilled professional to examine your furnace for broken-down parts, clogs in the air filters and other likely 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 ideal some filters be replaced 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 pulling air through a clogged filter makes the entire furnace work harder to do its job. And the harder your furnace needs to run, the more strain pieces like the heat exchanger will sustain.