5 Cracked Heat Exchanger Symptoms in Your Furnace

cracked heat exchangers

Jake Smith, Online Marketing Strategist
Technically Reviewed by Jake Smith, Online Marketing Strategist on Nov 09, 2023 | Written by Alpha Mechanical Editorial Contributors

Furnaces rely on a heat exchanger to supply warm air to your home. It is an essential part of the functioning of your heating system, and any complications with it or signs that your heat exchanger has gone bad will not only lead to a breakdown of your furnace but also present serious hazards to the health and safety of your home. A cracked heat exchanger in gas furnace if left unresolved can be detrimental. In this article we cover some determining signs of heat exchanger cracks and how to resolve the issues when they arise.

What is a Heat Exchanger in a Gas Furnace?

Inside of a furnace there is a sealed chamber where heat is created through combustion. This is the furnace heat exchanger and it commonly appears as a series of tubes located between the combustion chamber and the blower inside your gas furnace. The air that passes over the heat exchanger becomes warm while also isolating any toxic fumes from moving through the ductwork and into your lungs. It is a vital piece of the machinery that makes up your furnace as it is the driving force of your heat while simultaneously, through its air-tight seal protecting you from “flue gas”. This is what would make having a cracked heat exchanger in gas furnace an immediate issue.

If you have a higher efficiency furnace, there will be a primary and secondary heat exchanger. High-efficiency furnaces (90% or higher) contain a primary and secondary heat exchanger. The primary heat exchanger is located near the burner and produces the higher temperature of flue gas. The secondary heat exchanger is where the flue gas undergoes further heat exchange and water vapor forms. After having moved through the primary heat exchanger, the burning gas proceeds to the secondary heat exchanger. As water is changed from a vapor to a liquid, it releases more heat into the secondary heat exchanger. This is what makes the furnace even more efficient.

5 Cracked Heat Exchanger Symptoms

It is most likely that your furnace heat exchanger will continue to attempt operating at full capacity even with a crack leaving you with no early warning signs as Carbon Monoxide could be leaking into your home. This is why it is crucial that you have an annual HVAC inspection as well as keeping a strong eye out for the symptoms below as you are determining whether your heat exchanger is cracked. Below we address each symptom or sign of cracked heat exchanger with a few photos of cracked heat exchangers as examples.

Symptom #1 Furnace Flame Color Changes

You should be able to identify the color of the flame that is heating your air. Gas furnaces should always produce none other than a blue flame. Should you check and see that there is an orange or yellow tint to the flame, this could be a result of a failed heat exchanger or a sign that the heat exchanger is damaged and the gas mixture could be contaminated due to a crack in the heat exchanger.

Symptom #2 Soot Build-up

Soot builds up when there is a lack of proper combustion. Soot can accumulate in or around your furnace burners and can also appear when your furnace is failing to burn up the gas entirely as a result of a cracked heat exchanger or broken burner.

soot in heat exchanger

Symptom #3 Strong Odor in the House

When you have a faulty heat exchanger there may enter an unpleasant and strange smell similar to formaldehyde (or rotten eggs). These strong odors indicate a gas leak and you need to take this very seriously. More often than not, however, Carbon Monoxide (almost) never carries a scent. Carbon Monoxide is a highly flammable, odorless and colorless byproduct of using furnaces that burn fuel. Only a Carbon Monoxide detector will alert you by way of a loud siren/alarm to notify you that there has been this toxin detected in your home. If this device goes off, you must evacuate your home immediately and call the authorities.

Symptom #4 You hear loud sounds from your HVAC unit

If your heat exchanger is damaged, especially by a crack, when your thermostat begins a new heating cycle, you will likely hear a loud and alarming sound. Because your heat exchanger is made out of metal, the metal will expand/contract as it begins to heat up. If there is a crack in the metal somewhere, there will be a loud banging, popping or rattling sound as a result of this.

Symptom #5 Furnace Cracks and/or Corrosion

Where there is exterior corrosion, there is likely immense interior corrosion as well. If you visibly see any cracks or corrosion taking place around your furnace, not just the heat exchanger but also the diverter box or inducer motor, call a professional straight away. In order to identify a crack in the heat exchanger a visual inspection needs to be performed by a professional when you think that your heat exchanger has gone bad. Since the heat exchanger is situated in the middle of the furnace, inspecting the heat exchanger requires specific equipment and tools to inspect the metal casing of this piece. Using a mirror or video scope attached to a long pole, it has to be placed carefully inside the burners in order to properly see whether physical damage is present. In order to determine the causes of a cracked heat exchanger in your furnace, the age of your furnace must be considered as well.

cracked images of heat exchanger

Is a Cracked Heat Exchanger Really Dangerous?

Natural gas such as Carbon Monoxide, is poisonous and can be fatal. The most difficult part about having heat exchanger problems is that you never know when the natural gas such as Carbon Monoxide will leak as a result of the crack in the heat exchanger and this is like a silent death trap. Carbon Monoxide is a natural gas that is highly toxic. CO poisoning appears as health issues such as unexplained headaches, dizziness, nausea, breathlessness, strange collapses, unconsciousness, tiredness and problems with your eyesight. When these symptoms appear in yourself or your family members, it is crucial to reach out for heating and furnace replacement in Sacramento. Not only does it become necessary to replace the heat exchanger but it is essential to replace the furnace once CO has leaked into your home in any amount.

Alpha Mechanical is Your Go-to Solution for 

HVAC services in Fair Oaks

How Much Does It Cost To Repair or Replace Cracked Heat Exchanger?

Weighing out your options when it comes to an appliance as pricey as an HVAC unit for your home is very wise, however, in some instances repair is not always an option and replacement is no longer a choice when it comes to the safety of you and your family. Unfortunately, there is no patch work or way to seal cracks in a heat exchanger primarily because heat exchangers are not immune to normal wear and tear and sealing a crack will not solve the issue of the over piece when it continues to expand and contract, it would be liable to create more cracks. Replacing the part can cost several thousand dollars and is only recommended if your HVAC system is newer with an existing warranty on the exchanger.

This is one of the tricker pieces of your furnace because of its location in your furnace. The heat exchanger is positioned in such a way that in order to replace it, the entire furnace must be taken apart to do so. This means high labor costs even if the product is under your warranty. Additionally, most often a five star HVAC contractor in Sacramento is unable to or would not advise that anyone replace their heat exchanger unless it is under warranty and under 10 years old. If your furnace is older than 10 years, you will need to replace the entire furnace.

If you discover that your heat exchanger is no longer under warranty and your furnace is aging, consider switching to a more energy-efficient HVAC system and receive a SMUD HVAC rebate. The state of California is offering business owners and homeowners incentives towards the purchase of replacement HVAC units that are high efficiency variable speed units.

Alpha Mechanical is your

commercial HVAC contractor in Sacramento!

Final Thoughts

When you have discovered that you need to repair a cracked heat exchanger, you are left with only two routes of mending the situation: replace the exchanger or replace the furnace. It is possible that once a technician begins the process of dismantling your furnace in order to reach and replace your heat exchanger, other parts and controls in the furnace may also need replacement as well.

Most HVAC companies will not repair this product without warranty coverage as a result. Whether you need to call a professional in your service area for help with your heat exchanger or not, scheduling an annual inspection of your HVAC company can save you thousands of dollars each year when those extreme weather seasons come.

During these yearly examinations, the HVAC professional will inspect for cracks in your system while also preventing traditional damages that lead to a cracked exchanger such as clogged filters and blowers. If you are tired of the furnace and gas prices, it may be time to switch for heat pump installation in Sacramento as well. Either way, an annual check up with a qualified HVAC company, will provide you with

What does an HVAC tune-up consist of?

Frequently Asked Questions

Why is the heat exchanger important in the furnace?

It protects the user from harmful flue gasses and direct flames. Transfers heat from one heat source to another efficiently by heating the metal and carrying the heat via forced air through air ducts into the conditioned space.

When is a deceptive tactic used by an HVAC contractor to upsell a new HVAC system?

If a contractor states that a heat exchanger is cracked and is dangerous to use, they do not provide evidence of the failure. A contractor needs to provide pictures and/or carbon monoxide readings of the flue gasses.

What is a common myth about heat exchanger lifespan?

Technicians will say that 10 year old heat exchangers are at the end of their life. They will show signs of wear and tear such as rust or stains on the heat exchanger to provide evidence of its deterioration. However, most manufacturers provide a 20 year-to-lifetime warranty on their heat exchangers.

Common Cooling
and Heating Issues!
See If We Service
Your Neighborhood!
We Protect Your Investment.
100% Piece of Mind Coverage.
Use Our Exclusive Online Discounts!

Learning Resources

Take the Next Step

Contact Us Today

    we strive to put all our energy so that you save yours!

    we strive to put all our energy so that you save yours!

    Mon to Fri: 8am to 5pm
    Sat & Sun: Closed
    Call or Text
    (916) 848-5980
    10418 Fair Oaks Blvd
    Fair Oaks, CA 95628
    Mon to Fri: 8am to 5pm
    Sat & Sun: Closed
    Call or Text
    (916) 848-5980
    10418 Fair Oaks Blvd
    Fair Oaks, CA 95628
    Email Us
    Email Us
    Google Review Link
    Copyright © 2024 Alpha Mechanical Systems, Inc. All Rights Reserved.  |  Privacy Policy  |  Terms & Conditions  |  Contact Us
    Call Now Button