A furnace is usually a background player at home, keeping you warm across the cold winter months. It frequently won't be noticed until a malfunction appears. 

One source could be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s worthwhile to know the symptoms of a cracked heat exchanger and what you can do if you believe that is the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger helps move heat from the combustion chamber inside your furnace to the air that moves through the system. It usually accomplishes this with coils or tubes that heat the air while serving as a barrier to keep byproducts 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’s no surprise that a cracked heat exchanger can be very dangerous. A crack in the heat exchanger can permit dangerous gasses – like carbon monoxide, which can be lethal – to flow across your home. 

For obvious reasons, never turn on your furnace if you think 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 believe your heater has a cracked heat exchanger that needs repair. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: A crack in your heat exchanger can cause your furnace to shut off. 
  • Odd Smells: If the air coming out of your furnace has a strong chemical odor, it could be a sign gas is seeping through cracks in your heat exchanger. These byproducts, which may smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm initiates or you notice health problems: If a cracked heat exchanger is relieving carbon monoxide into your home, your carbon monoxide alarm should go off or household members could experience signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If your alarm goes off or you feel unusually tired, get out of the home immediately and then call for help. 
  • Soot: If you notice black sooty accumulating on the exterior of your furnace, it’s another sign something could be seriously wrong.

What to Do if the Furnace Heat Exchanger is Cracked 

If you worry your furnace has a cracked heat exchanger, contact a pro well versed in furnace installation Magnolia right away so they can examine your system and, if required, perform a furnace heat exchanger replacement. Costs should fluctuate depending on the situation, but estimates often hover around $1,000 to $3,000. 

Fortunately, the good news is that heat exchangers are regularly included in 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 still may significantly reduce your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the most convenient ways to avoid problems in your furnace overall is with consistent furnace maintenance. Furnaces offer the most benefits when they work efficiently. Contacting a trained professional to check your furnace for broken-down parts, clogged filters and other common problems can help you avoid getting a big bill later on.  

It’s also beneficial to inspect 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 aren't a part of the heat exchanger itself, the strain of pulling air through a clogged filter makes your entire furnace work longer to complete its job. And the harder your furnace has to work, the more strain pieces like the heat exchanger will endure.