A furnace is usually a background player at home, ensuring you're warm during the cold winter months. It often doesn’t get noticed until something goes wrong. 

One cause could be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s important to learn the signs of a cracked heat exchanger and what to do if you believe that might be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger helps transition heat from the combustion chamber inside your furnace to the air that moves through the air ducts. It generally handles this using coils or tubes that warm the air while serving as a barrier to keep the gasses formed in the combustion chamber, called flue gasses, from getting out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Given its central role, it isn't surprising that a broken heat exchanger can be very dangerous. A damaged heat exchanger can enable dangerous gasses – like carbon monoxide, which can be lethal – to flow across your home. 

For that reason, never turn on your heater if you believe you're dealing with a cracked heat exchanger, as letting it run could make the whole household ill. Call an HVAC professional as soon as possible if you believe your heater has a cracked heat exchanger that needs to be repaired. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: Cracks in the heat exchanger may cause your furnace to turn off. 
  • Odd Smells: If the air leaving your furnace has a powerful chemical odor, it may be a sign gasses are seeping through cracks in your heat exchanger. These gasses, which may smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm goes off or you feel health problems: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm may go off or household members might start experiencing signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If the alarm goes off or you feel unwell, leave the home as soon as you can and then call for help. 
  • Soot: If you see black sooty accumulating on the exterior of your furnace, it’s an indication something may be seriously wrong.

What You Should Do if the Furnace Heat Exchanger is Cracked 

If you suspect your furnace has a cracked heat exchanger, contact a pro well versed in furnace installation Redmond right away so they can examine your system and, if needed, handle a furnace heat exchanger replacement. Costs will differ depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000. 

However, the good news is that heat exchangers are often protected by the warranty. You’ll want to confirm the warranty paperwork on your furnace, since while the warranty might not cover the entire cost of repairs, it can significantly reduce your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the easiest ways to avoid problems in your furnace overall is with regular furnace maintenance. Furnaces offer the most benefits when they operate efficiently. Contacting a certified professional to inspect your furnace for old parts, clogged 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 ideal 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 harder to do its job. And the harder your furnace has to work, the more wear and tear pieces like the heat exchanger will sustain.