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You are in Phoenix. We also have a Tucson site.

Top Signs of Cracks in Heat Exchanger


Did you know that a cracked heat exchanger in your furnace can be as dangerous as a gas leak? Yes, it's not just a minor inconvenience. It's a serious issue that can affect your home's safety and efficiency. In this article, we’ll dive into what causes cracks in heat exchanger systems, how to spot them, and what to do if you suspect a problem. You’ll learn about the warning signs, health risks, and maintenance tips. Keep reading to ensure your home stays warm and safe this winter.

Quick Facts

  • Heat exchangers keep your home warm by transferring heat from burning fuel to circulating air and they wear out after 10-20 years.

  • Watch out for signs of a cracked heat exchanger, such as unusual odors, soot accumulation, rattling sounds, and unexpectedly high gas bills; these are major warning indicators.

  • If you suspect a crack, get a professional inspection immediately. Cracks cannot be repaired and pose significant health risks, including carbon monoxide leaks.

What is a Heat Exchanger?

A heat exchanger is an essential component of your heating system. It consists of tubes and coils that warm the air before it’s circulated throughout your home. Situated between the combustion chamber and the blower in a gas furnace, it efficiently transfers heat from the burning fuel to the circulating air, ensuring your home stays cozy during the heating season. The furnace heat exchanger is crucial for effective heat transfer, optimizing the performance of your heating system.

The furnace's heat exchanger operates by blowing cooler air over its surface to heat it before it’s distributed throughout your home, which is crucial for your heating system. Constructed from metal and designed for heat transfer, the heat exchanger includes a primary section that utilizes the hottest flue gas and a secondary section that captures flue gas heat and produces water vapor. This configuration ensures your heating system remains efficient.

Common Causes of Cracks in Heat Exchangers

Cracked heat exchangers are usually caused by several factors:

  • Age

  • Neglecting essential maintenance

  • Overheating

  • Improperly sized furnace

  • Corrosion from moisture exposure

One of the primary reasons for cracked heat exchangers is age. Most heat exchangers show signs of wear and tear between 10 and 20 years, just from regular use. Neglecting essential maintenance tasks, such as cleaning and replacing a clogged furnace's heat exchanger, can significantly increase the risk of developing cracks in the heat exchanger.

Overheating is another significant cause of cracked heat exchangers. This can happen due to restricted airflow or malfunctioning thermostats causing excessive heat in the furnace. An improperly sized furnace, whether too big or too small, can also cause the heat exchanger to overheat and crack. Corrosion from moisture exposure also contributes to cracks and holes in the failed heat exchanger.

Dangers of a Cracked Heat Exchanger

A cracked heat exchanger poses serious health and safety risks to homeowners. One of the most significant dangers is the potential for carbon monoxide leaks. When a heat exchanger is cracked, it can allow harmful gases to escape into your home, creating a hazardous environment. The presence of a cracked heat exchanger poses not only a threat to your heating system’s efficiency but also to the well-being of everyone in your household.

Signs Your Heat Exchanger is Cracked and Carbon Monoxide Poisoning

Recognizing the early warning signs of a cracked furnace heat exchanger can save you from extensive damage and expensive repairs. From unusual odors to strange noises, here are the key indicators.

Let's break them down.

Strange Smells

One of the first signs of a bad furnace's heat exchanger is a strong smell coming from your furnace. This can be a formaldehyde smell which is not only unpleasant but also harmful to your health. These smells usually mean harmful gases including combustible gases are leaking into your home and need to be addressed immediately.

Addressing strange smells promptly is crucial for safety. These odors can indicate underlying issues with your heat exchanger that, if ignored, can escalate into significant problems. If you detect an unusual smell coming from your furnace, contact a professional to inspect it and ensure your system is operating safely.

Soot Buildup

Soot around your furnace burners is a telltale sign of incomplete combustion, often stemming from a damaged furnace heat exchanger. Inefficient combustion produces soot, which then accumulates around various furnace components. Incomplete combustion not only indicates a higher likelihood of heat exchanger cracks but also affects the overall efficiency of your furnace. Additionally, soot buildup poses a carbon monoxide hazard, making it crucial to monitor and address any accumulation promptly.

Flame Color Changes

The color of the flame in your gas furnace is an indicator of its health. A healthy furnace produces a blue flame which means proper combustion and efficient system. If you see the flames turning yellow or orange, it means there’s an issue with your furnace's heat exchanger and combustion quality.

A yellow flame signifies heat exchanger damage. It's crucial to address these changes to maintain your system's efficiency and safety.

Rattling Noises

Unusual sounds like rattling, popping, or banging can also be signs of a cracked furnace's heat exchanger. These noises are usually caused by metal expansion and contraction within the heat exchanger which means damage and needs a pro to inspect.

High Gas Bills

If you’ve noticed a sudden increase in your natural gas bills, it could be because of a faulty furnace's heat exchanger in your gas furnaces making your furnace work harder to maintain the desired temperature. This inefficiency means higher energy consumption and costs. Checking gas bills helps you catch inefficiencies early. A damaged heat exchanger decreases heating efficiency, so it's crucial to monitor any sudden spikes in energy costs.

Carbon Monoxide Leaks

Carbon monoxide is a colorless, odorless, and tasteless gas that can be deadly in high concentrations. When a heat exchanger is cracked, it can allow carbon monoxide to escape into the home’s air ducts, posing a significant risk to occupants. Carbon monoxide poisoning can cause headaches, dizziness, nausea, breathlessness, and even death. It is essential to have a carbon monoxide detector installed in the home to alert occupants of potential leaks.

How Regular Maintenance Can Prevent Cracks

Regular maintenance is crucial for preventing cracks in your furnace's heat exchanger. Yearly furnace inspections are recommended to catch and address any issues before they lead to more severe problems. Poor maintenance accelerates the deterioration of heat exchangers, increasing the likelihood of cracks.

Annual servicing by a qualified professional can prevent cracked heat exchangers. Servicing includes cleaning out dirt and dust buildup and ensuring all components are working properly, which helps avoid stress cracks and maintains your system’s efficiency.

What to Do If Your Heat Exchanger Is Cracked

If you suspect that your heat exchanger is cracked, it is crucial to take immediate action to ensure your safety and the safety of your home. Here are the steps you should follow:

  1. Turn off the furnace: Immediately switch off the furnace to prevent further damage and potential carbon monoxide leaks. This step is crucial to stop the flow of harmful gases into your home.

  2. Evacuate the home: If you suspect a carbon monoxide leak, evacuate the home and call 911 or your local emergency number. It’s better to be safe and ensure that everyone is out of harm’s way.

  3. Contact a professional: Reach out to a licensed HVAC technician to inspect and diagnose the issue. They will be able to determine the extent of the damage and recommend the necessary repairs or replacement. A professional assessment is essential to ensure that the problem is correctly identified and addressed.

  4. Replace the heat exchanger or furnace: Depending on the severity of the damage, it may be necessary to replace the heat exchanger or the entire furnace. A professional technician will be able to advise on the best course of action. Replacing a faulty heat exchanger can restore your heating system’s efficiency and safety.

  5. Schedule regular maintenance: To prevent future heat exchanger cracks, schedule regular maintenance with a licensed HVAC technician. They will be able to inspect the furnace and heat exchanger, clean and replace filters, and perform any necessary repairs to ensure the system is running safely and efficiently. Regular maintenance is key to extending the life of your heating system and preventing costly repairs.

Remember, a cracked heat exchanger is a serious issue that requires immediate attention. Don’t risk your safety and the safety of your loved ones – take action today to ensure your home is safe and warm. By following these steps, you can address the problem promptly and maintain a safe and efficient heating system.

Schedule an Inspection with Parker & Sons

Parker & Sons utilizes high-quality components to give your furnace the attention it deserves. Book an inspection with us to catch any problems early and maintain a warm and secure home all season long. Because, let's face it, everyone prefers a furnace that behaves! 

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