A furnace is usually a background player for your home, helping keep you warm in 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 can be a safety risk, so it’s important to know the symptoms of a cracked heat exchanger and what you can do if you are worried that is the problem.  

What Is a Heat Exchanger in a Furnace? 

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

Is a Cracked Heat Exchanger Dangerous? 

Given its central role, it shouldn't come as a surprise that a cracked heat exchanger can pose a risk. A damaged heat exchanger can enable dangerous gasses – like carbon monoxide, which can be lethal – to circulate through your home. 

For that reason, do NOT use your heater if you think you're dealing with a cracked heat exchanger, as this could make the whole household sick. Contact an HVAC professional immediately if you think your heater has a cracked heat exchanger that should be repaired. 

Four Symptoms of a Cracked Heat Exchanger: 

  • Furnace switches off: Cracks in the heat exchanger could cause your furnace to switch off. 
  • Strange Smells: If the air escaping your furnace has a strong chemical smell, it could be a sign gas is slipping through cracks in your heat exchanger. These gasses, which will often smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm initiates or you recognize poisoning symptoms: If a cracked heat exchanger is releasing carbon monoxide into your home, your carbon monoxide alarm may go off or household members may experience signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If your 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 find black sooty accumulating around the exterior of your furnace, it’s another sign something might be seriously wrong.

What You Can Do if Your Furnace Heat Exchanger is Cracked 

If you worry your furnace has a cracked heat exchanger, hire a professional with extensive experience in furnace installation Pocatello as soon as possible so they can examine your system and, if needed, perform a furnace heat exchanger replacement. Costs should fluctuate depending on the situation, but estimates can roughly suggest $1,000 to $3,000. 

Estimates aside, the good news is that heat exchangers are regularly included in the warranty. You’ll want to confirm the warranty paperwork on your furnace, since while the warranty may not cover the entire cost of repairs, it could significantly reduce your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the easiest ways to minimize the risk of problems in your furnace overall is with routine furnace maintenance. Furnaces provide the best possible return on investment when they operate efficiently. Contacting a trained professional to examine your furnace for broken-down parts, dirty filters and other common problems can keep you from getting a big bill later on.  

It’s also beneficial to review your furnace filters every few months – it’s encouraged 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 drawing air through a clogged filter makes your entire furnace work more vigorously to accomplish its job. And the harder your furnace works, the more deterioration components like the heat exchanger will endure.