5 Cracked Heat Exchanger Symptoms in Your 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.

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.

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.

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.