A furnace is often a background player in your home, keeping you warm during the cold winter months. It often isn't noticed until something breaks down. 

One cause might be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s important to familiarize yourself with the signs 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 of your furnace to the air that circulates inside the ventilation. It generally accomplishes this via coils or tubes that heat up the air while serving 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 key role, it isn't surprising that a broken heat exchanger can pose a risk. A damaged heat exchanger can allow dangerous gasses – like carbon monoxide, which can be lethal – to flow through your home. 

For this reason, do NOT run your heater if you believe it has a cracked heat exchanger, as letting it run could make your entire household ill. Contact an HVAC professional immediately if you are worried your heater has a cracked heat exchanger that needs to be repaired. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: A cracked heat exchanger could cause your furnace to shut off. 
  • Strange Smells: If the air coming out of your furnace has a strong chemical scent, it may be an indicator that gas is leaking through cracks in your heat exchanger. These gasses, which will often smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm goes off or you notice symptoms of poisoning: If a cracked heat exchanger is emitting carbon monoxide in your home, your carbon monoxide alarm may go off or family members might start experiencing signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If your alarm goes off or you feel unusually tired, exit the home immediately and then call for help. 
  • Soot: If you notice black sooty collecting near the exterior of your furnace, it’s an indication something may be seriously wrong.

What You Should Do if Your Furnace Heat Exchanger is Cracked 

If you worry your furnace has a cracked heat exchanger, hire a pro experienced in furnace installation Auburn and Opelika as soon as possible so they can inspect your system and, if needed, start a furnace heat exchanger replacement. Costs will differ depending on the situation, but estimates often hover around $1,000 to $3,000. 

Fortunately, the good news is that heat exchangers are regularly covered by the warranty. You should confirm the warranty paperwork on your furnace, because while the warranty won't always cover the entire cost of repairs, it could significantly shrink your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the best ways to avoid problems in your furnace overall is through regular furnace maintenance. Furnaces provide the best possible return on investment when they run efficiently. Calling a certified professional to inspect your furnace for old parts, clogged filters and other common problems can keep you from getting a big bill later on.  

It’s also a good idea to inspect 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 pulling air through a clogged filter makes your entire furnace work longer to do its job. And the harder your furnace needs to run, the more strain components like the heat exchanger will experience.