For some who may not be familiar with what a heat exchanger is, let’s start here. The heat exchanger is simply, the parts inside a gas furnace that heat the air. The difficult part is that it’s not readily accessible or visible without disassembling the furnace. It’s metal and made up of tubes or coils that are looped repeatedly inside the furnace. It’s a combination metal chamber and passageway that starts at the burner assembly and ends approximately where the chimney vent connects to the furnace. Air is heated as it is blown across the hot metal surface of the heat exchanger. The heated air is then distributed through the house. It is VERY important the coils of the heat exchanger remain fully sealed. The combustible air from the furnace needs to be kept completely separate from the air we breathe, we’ll visit more about that in a bit.
#1: WHY IS THE HEAT EXCHANGER SO IMPORTANT?
We’ve discussed in some of our other blogs about maintaining a healthy home and the benefits it provides you and your loved ones. This is a biggie and it’s worth re-visiting. If your heat exchanger is cracked, it can be incredibly dangerous for those inside the home. The dangerous gasses contained within the heat exchanger can be released into to the air we breathe which can cause serious illness and sometimes death. The most dangerous gas released is Carbon Monoxide. It’s odorless but deadly when exposure is high. Other common pollutants that can enter your home’s air through a crack in your heat exchanger include:
- Carbon dioxide
- Nitrogen oxides
To lean more about Carbon Monoxide, visit the CDC website .
#2: HOW OLD IS IT?
Prediction: your heat exchanger will crack or fail. That’s the very simple reality of it. Don’t blame the furnace company, blame metal fatigue. With that in mind, a key piece of info is your furnace’s age. Metal expands when it’s heated, that’s just physics. When it cools, it contracts. Here in Nebraska and Iowa, we have an ‘above average’ on extreme temperatures during summers and winters. Because of our climate, we run both our heaters and air conditioners quite a bit. (sometimes in the same day) This means the metal that seals the gasses inside the heat exchanger moves around alot. Similar to a paperclip that’s bent back and forth, over and over again. The metal weakens and eventually breaks…Physics. Heat exchangers are built to last 10 to 20 years, but that’s only an estimate depending on usage. Not having proper maintenance performed by a licensed professional will also take years off the life of a heat exchanger so be diligent. Knowing the age of your furnace will help gauge it’s useful life remaining. (Keep in mind, heat exchangers cannot be repaired. They must be replaced, and it can be a costly event!)
#3: COMMON SIGNS OF A CRACK
We’re getting there, keep reading! The last part you, the homeowner can do to uncover signs and red flags of a cracked heat exchanger is look for the most common indictaions:
- Flame appearance: You know the flame in your furnace? It should be blue if you have a regularly-functioning gas furnace. If the heat exchanger is cracked (or if the burner is dirty), you’ll see a moving yellow flame. That’s a sign to call an HVAC pro.
- Soot build up: Referenced above, soot can leak out of a cracked heat exchanger. If you remove the furnace face and see a black carbon buildup on the surfaces, this is another sign of a possible crack in your heat exchanger.
- Unusual smells: Cracked heat exchangers generally produce a strong and unpleasant smell, kind of like formaldehyde. It may give you headaches and other physical symptoms. Call your licensed HVAC pro.
Since heat exchangers are not readily accessible, (without disassembling the unit) diagnosing cracks requires specific testing methods that are typically outside the scope of a traditional home inspection AND standard service appointment. Be specific in requesting it to be checked especially if your furnace is older than 12 years and remember….make sure it is done by a licensed HVAC professional. Note: High efficiency furnaces have a different criteria when it comes to investigating.
Hopefully we’ve shed some light on signs of a cracked heat exchanger and what you, the responsible home owner can do to keep your furnace and heat exchanger running safe it’s best.
If you are having a home inspection with AmeriSpec, we offer a more exhaustive furnace inspection though one of our preferred partners, which includes testing the heat exchanger. Call for pricing, it’s a fraction of what you’ll find from any HVAC company.
Reducing the risk and adding more value to your home inspection. That’s the AmeriSpec difference.
- On November 21, 2017
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