A furnace is usually a background player for your home, keeping you warm in the cold winter months. It regularly isn't 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 critical to know the signs of a cracked heat exchanger and what you can do if you suspect that is 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 circulates through the system. It usually accomplishes this with coils or tubes that heat up the air while acting as a barrier to keep gas formed in the combustion chamber, called flue gasses, from leaking out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Thanks to its central role, it isn't surprising that a cracked heat exchanger can be hazardous. Cracks in the heat exchanger can permit dangerous gasses – such as carbon monoxide, which can be lethal – to circulate through your home. 

For that reason, do NOT turn on your heating if you believe you're dealing with a cracked heat exchanger, as letting it run could make your entire household ill. Reach out to an HVAC professional immediately if you are worried your furnace has a cracked heat exchanger that should be repaired. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace turns off: A crack in your heat exchanger can cause your furnace to turn off. 
  • Odd Smells: If the air escaping your furnace has a strong chemical odor, it might be evidence gas is leaking through cracks in your heat exchanger. These gasses, which can smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm initiates or you recognize symptoms of poisoning: If a cracked heat exchanger is releasing carbon monoxide into your home, your carbon monoxide alarm should go off or household members could struggle with signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If the alarm goes off or you feel sick, exit the home as soon as you can and then call for help. 
  • Soot: If you find black sooty accumulating near the exterior of your furnace, it’s an indication something could be seriously wrong.

What You Should Do if a Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, call a pro experienced in furnace installation Big Spring as soon as possible so they can take a look at your system and, if necessary, handle a furnace heat exchanger replacement. Costs will fluctuate depending on the situation, but estimates often hover around $1,000 to $3,000. 

Estimates aside, the good news is that heat exchangers are regularly included in the warranty. You should check the warranty paperwork on your furnace, since while the warranty may not cover the entire cost of repairs, it could significantly shrink your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the best ways to minimize the risk of problems in your furnace overall is via routine furnace maintenance. Furnaces provide the best possible return on investment when they run efficiently. Contacting a certified professional to examine 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 encouraged some filters be swapped out 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 drawing air through a clogged filter makes your entire furnace work harder to complete its job. And the harder your furnace has to work, the more wear and tear parts like the heat exchanger will endure.