A furnace is almost always a background player in your home, ensuring you're warm in the cold winter months. It regularly won't be noticed until something goes wrong. 

One 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 signs of a cracked heat exchanger and what you can do if you believe that may be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger transfers heat from the combustion chamber in your furnace to the air that circulates inside the system. It generally handles this through coils or tubes that heat the air while functioning as a barrier to keep the gasses produced in the combustion chamber, called flue gasses, from escaping out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Given its important role, it’s no surprise that a damaged heat exchanger can be very dangerous. A damaged heat exchanger can allow dangerous gasses – including carbon monoxide, which can be lethal – to circulate throughout your home. 

For this reason, don't ever use your heating if you think it has a cracked heat exchanger, as this could make the entire family sick. Reach out to an HVAC professional immediately if you are worried your heating has a cracked heat exchanger that needs repair. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace shuts off: A crack in your heat exchanger could cause your furnace to shut off. 
  • Odd Smells: If the air leaving your furnace has a strong chemical odor, it could be an indicator that gasses are leaking through cracks in your heat exchanger. These byproducts, which will often smell like formaldehyde, are a major warning sign. 
  • Carbon monoxide alarm goes off or you notice health problems: If a cracked heat exchanger is relieving carbon monoxide inside your home, your carbon monoxide alarm should go off or household members might start experiencing signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If an alarm goes off or you feel sick, get out of the home as soon as you can and then call for help. 
  • Soot: If you spot black sooty collecting around the exterior of your furnace, it’s an indication something may be seriously wrong.

What You Can Do if the Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, hire a professional with extensive experience in furnace installation Tucson and Phoenix as soon as possible so they can inspect your system and, if required, perform a furnace heat exchanger replacement. Costs will differ 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 generally included in the warranty. You should review the warranty paperwork on your furnace, because while the warranty may not cover the entire cost of repairs, it can significantly lower your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the most convenient ways to minimize the risk of problems in your furnace overall is with consistent furnace maintenance. Furnaces provide the best possible return on investment when they run efficiently. Contacting a trained professional to inspect your furnace for worn-out parts, clogs in the air filters and other potential problems can help you avoid getting a big bill later on.  

It’s also beneficial to review your furnace filters every few months – it’s recommended 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 longer to complete its job. And the harder your furnace has to work, the more wear and tear components like the heat exchanger will experience.