A furnace is often a background player for your home, keeping you warm in the cold winter months. It regularly doesn’t get noticed until something goes wrong. 

One cause may be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s worthwhile to know the signs of a cracked heat exchanger and what you should do if you suspect that might be 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 flows through the ventilation. It generally accomplishes this through coils or tubes that heat up the air while serving as a barrier to keep gas produced in the combustion chamber, called flue gasses, from leaking out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Because of its key role, it’s no surprise that a broken heat exchanger can pose a risk. Cracks in the heat exchanger can allow dangerous gasses – such as carbon monoxide, which can be lethal – to be distributed across your home. 

For obvious reasons, don't ever use your furnace if you suspect there's a crack in the heat exchanger, as doing so could make the entire household sick. Contact an HVAC professional right away if you are worried your heating has a cracked heat exchanger that should be repaired. 

Four Symptoms of a Cracked Heat Exchanger: 

  • Furnace turns off: A cracked heat exchanger could cause your furnace to switch off. 
  • Unusual Smells: If the air escaping your furnace has a strong chemical odor, it might be evidence gas is leaking through cracks in your heat exchanger. These gasses, which may smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm goes off or you recognize poisoning symptoms: If a cracked heat exchanger is emitting carbon monoxide inside your home, your carbon monoxide alarm should go off or household members may start experiencing signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If the alarm goes off or you feel unwell, leave the home immediately and then call for help. 
  • Soot: If you spot black sooty collecting near the exterior of your furnace, it’s more evidence something might 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 professional with extensive experience in furnace installation Pflugerville as soon as possible so they can inspect 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. 

Fortunately, the good news is that heat exchangers are often protected by the warranty. It's a good idea to confirm the warranty paperwork on your furnace, since while the warranty might 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 easiest ways to prevent a problem in your furnace overall is via regular furnace maintenance. Furnaces provide the best possible return on investment when they run efficiently. Contacting a trained professional to inspect your furnace for broken-down parts, dirty filters and other potential problems can help you avoid getting a big bill later on.  

It’s also beneficial to inspect 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 pulling air through a clogged filter makes your entire furnace work more vigorously to complete its job. And the harder your furnace works, the more deterioration parts like the heat exchanger will sustain.