Heat exchangers fail for a number of reasons. Here’s a brief run down that will help you as a technician or a homeowner.
A furnace heat exchanger serves mainly two purposes.
1. Purpose number one is to keep exhaust fumes from entering your home via the air stream. Safety.
2. To absorb the energy from the burned fuel. Then it is moved from the metal heat exchanger to the building via a duct system. The blower moves air across the heat exchanger thus exchanging the heat from the furnace to the house. Efficiency and comfort.
Picture of a heat exchanger
Why do Heat Exchangers Fail?
1. Lack of airflow is the number reason. Result of a poorly sized duct system, oversized furnace, dirty filters, dirty coil or a dirty secondary coil.
2. Manufacturers poor design
3. Poor installation
4. Lack of regular routine maintenance
5. Oversized or over fired furnace
6. Age. Furnaces will wear out. That’s a fact.
Why all the buzz about failed heat exchangers?
Most companies will tell you that it’s because you can get sick or die from carbon monoxide poisoning. Though, this is possible it is less likely today as the newer furnaces are designed with more safety controls and most likely will shut down under a failure. However, heat exchangers fail in a number of ways thus the safety concern is no longer the only concern.
Here is a list of concerns regarding a failed heat exchanger.
1. Safety. Failed heat exchangers can cause an unsafe situation.
2. Comfort. A failed heat exchanger can cause the furnace to run a different cycle time. This can cause comfort issues.
3. Efficiency. With the unstable costs of energy a plugged or malfunctioning heat exchanger can gobble up your money. It’s no different than running the water if you pay a municipal sewer and water bill. You are purchasing a fuel to heat your home. If the heat exchanger is not absorbing the heat correctly this can cause an increase in your utility bill.
4. Other failures. If your secondary heat exchanger is plugged this will cause additional wear on your blower motor causing more electrical consumption and may cause a premature failure of the motor.
What are the most common heat exchanger failures?
1. Cracks, fractures, pitting, holes and ruptures
2. Hot spots, warping, bulges and heat stress
3. Plugging, corroded or sooted
4. Manufacturers defects or poor engineering
Picture of a cracked heat exchanger
Picture of a hole in a heat exchanger
Picture of a plugged secondary
Picture of a corroded secondary
What’s the best way to protect my furnace?
1. Have it serviced – PROPERLY!
2. Change or clean your filters
Picture of a badly plugged evaporator coil
Picture of a badly plugged air filter
Picture of a dirty secondary coil
Picture of a dirty blower wheel
Written by: Steve Holland of heatexchangersafety.com
Steve Holland is a 25 year industry veteran and owns several Heating and Air Conditioning Companies in Wisconsin. Mr. Holland’s Heating and Air. Bloedel’s Heating and Cooling. Holland Heating and Air Conditioning. Steve is a featured speaker at many tech schools in Wisconsin and is available for training, conversation and a host of other business growth and development topics.