Close up shot of copper plain tubes of a condenser coil

All About Furnace Heat Exchangers

Furnace heat exchangers are the portion of the furnace which is tasked with keeping the combustion process and breathing air separate. This is crucial since it prevents poisoning by carbon monoxide.  It starts near the furnace burn assembly and will go to an area where a chimney vent will connect to the furnace. The passageway, when combined with the metal chamber, will enable heated air to be safely distributed throughout the building, and heat exchanges can be also found in everything from pools to refrigerators and vehicles.

How Furnace Heat Exchangers Operate

At the most basic level, the heat exchanger will function by transferring or exchanging heat that is generated inside a combustion chamber. It will be sent to the unit’s exterior where it can then be blown inside the ductwork and into the building. This is accomplished in three phases, which are:

  • Once a request for heat has been made by the furnace, the combustion procedure will begin. The heated gases will enter the heat exchanger’s chamber and will heat the metallic walls.
  • Returned air ducts will draw the cold air from inside the building and then blow it onto the heat exchanger’s exterior. This cold air will then become warm due to contact with the exchanger’s heated walls after which it will be returned via the ducts into the different rooms of the property, and the breathable air and combustion gases are always kept separate.
  • The gases which are generated during combustion will be subsequently blown out of the heated exchanger and into external vents leading outside the property. However, higher efficiency condenser furnaces function a bit differently, since their gases move through the secondary heat exchanger which enables the drawing of extra heat for home-usage.

Advantages of Using Furnace Heat Exchanges

The primary advantage of using heat exchange furnaces is that they help in ensuring occupants remain safe from any combustion byproducts. Otherwise, the hazardous glue gases could mix with breathing air, which could result in the poisoning and death of every human and animal in the building. This is why it is essential to install carbon monoxide based detectors in any property that uses fuel-burning machines, and in some jurisdictions, it is mandated by law.

Heat Exchanger Challenges

While the heat exchange mechanism is highly effective, it does have its challenges. For instance, all these machines are vulnerable to a phenomenon called metal fatigue which can result in their eventual failure. This happens because the metallic walls are continually being heated and then cooled which causes a cycle of expansion and contraction. However, since the majority of heat exchangers last from ten to twenty years, you won’t have to replace them often, but there are a number of things you’ll want to avoid to prevent premature failure:

  • Inadequate installation
  • Insufficient maintenance
  • Low-quality equipment design

You’ll want to hire an HVAC professional who is qualified to perform an examination of the heat exchanger to detect any holes or cracks. They can do this with an infrared-style video inspection tool, and if cracks or holes are discovered, they should be replaced.

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