A furnace is almost always a background player in your home, helping keep you warm during the cold winter months. It regularly doesn’t get noticed until something goes wrong. 

One cause could 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 to do if you are worried that is the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger helps transition heat from the combustion chamber of your furnace to the air that moves inside the ventilation. It generally handles this via coils or tubes that warm the air while serving as a barrier to keep the gasses produced in the combustion chamber, called flue gasses, from leaking out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Because of its important role, it isn't surprising that a broken heat exchanger can be hazardous. A crack in the heat exchanger can enable dangerous gasses – like carbon monoxide, which can be lethal – to be distributed across your home. 

For obvious reasons, don't ever run your heater if you believe it has a cracked heat exchanger, as this could make the entire family sick. Contact an HVAC professional right away if you think your heater has a cracked heat exchanger that needs to be repaired. 

Four Symptoms of a Cracked Heat Exchanger: 

  • Furnace turns off: A cracked heat exchanger can cause your furnace to turn off. 
  • Strange Smells: If the air leaving your furnace has a powerful chemical scent, it may be evidence gas is seeping 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 recognize symptoms of poisoning: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm could go off or family members might start experiencing signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If the alarm goes off or you feel sick, leave the home immediately and then call for help. 
  • Soot: If you find black sooty accumulating on the exterior of your furnace, it’s an indication something might be seriously wrong.

What You Should Do if Your Furnace Heat Exchanger is Cracked 

If you suspect your furnace has a cracked heat exchanger, hire a pro with extensive experience in furnace installation Des Moines as soon as possible so they can inspect your system and, if necessary, start a furnace heat exchanger replacement. Costs will vary depending on the situation, but estimates often hover around $1,000 to $3,000. 

Estimates aside, the good news is that heat exchangers are generally protected by the warranty. You should review the warranty paperwork on your furnace, because 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 most convenient ways to prevent a problem in your furnace overall is via routine furnace maintenance. Furnaces provide the best possible return on investment when they run efficiently. Calling a skilled professional to examine your furnace for worn-out parts, dirty filters and other likely problems can help you avoid getting a big bill later on.  

It’s also helpful 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 drawing air through a clogged filter makes the entire furnace work more vigorously to accomplish its job. And the harder your furnace has to work, the more strain parts like the heat exchanger will endure.