Defective Heat Exchangers

Heat exchangers are the heart of any forced air furnace. Their purpose is to provide heat from the combustion process to the air being moved by the furnace’s blower, and eventually deliver that heated air to the home or business. Occasionally, heat exchangers fail and the equipment needs to be replaced. This article will cover some key topics of heat exchangers: Why do they the fail? Are defective heat exchangers dangerous? What options do I have when a defective heat exchanger is the diagnosis?

Why Do Heat Exchangers Fail?

Generally forced air furnaces are designed to last an average of 18 years. Many manufacturers provide a 20 year or lifetime warranty on the heat exchanger. No manufacturer designs a furnace to fail. So, the million-dollar question is — why do they fail?

Before we dive into this question, lets describe heat exchange failure of a forced. Heat exchangers can fail in two distinct ways. Either they become brittle and break physically, creating a path for combustion gases to get into the people space, or they become fouled or plugged and cannot successfully transmit exhaust gases to the outdoors. Heat exchanger failures typically come from 3 key areas: incorrect installation, neglect in maintenance, or reaction with chemicals.

Installation Errors

Installation errors come from the manner on which the furnace was installed and commissioned (configured). Manufactures provide a furnace, but they do not provide the necessary material to make the furnace operate properly. The required connections are usually used governed by some type of code or standard. Sometimes, the manufacturer’s literature gives guidance on how the furnace should be set up.

Incorrect venting of the exhaust gases is the number one cause of heat exchanger failures. Either the installing contractor used the incorrect materials, or the piping may be sized incorrectly. When the exhaust piping is not correct, the flow rate of the exhaust gases is altered; this causes severe damage to the furnace’s heat exchanger. Air flow for the furnace is also another key contributor to the failure of furnace heat exchangers. When airflow is poor, the furnace’s heat exchanger overheats; this causes the metal in the heat exchanger to expand and contract outside of its limits. A lack of maintenance can mimic the same situation. Dirty filters can also cause the furnace’s heat exchanger to overheat and fail. Lastly, as with cars, sometimes there are manufacturer’s defects with some of the forced air furnace products. The Carrier Corporation has a current recall on a certain generation of furnaces that were manufactured with a compromised heat exchanger. There have also been reports from manufacturers that certain laundry and other chemicals that are stored near the furnace may interact with the furnace’s heat exchanger and accelerate failure. The Carrier, Bryant, and Payne corporations have a current recall on a certain generation that has a manufacturer’s defect. Contact us for more information to process these warranty claims.

Why is a Defective Heat Exchanger Dangerous?

Maybe this has happened to you? An HVACR service technician indicated that the furnace’s heat exchanger has failed, and that the equipment most be removed from service. The context of this situation cannot go understated. When heat exchangers fail, quite often there is carbon monoxide generation. Carbon Monoxide is an odorless, tasteless, colorless, poisonous gas. If your furnace is producing excessive levels of carbon monoxide, the technician is acting morally to protect you from the malfunctioning appliance. Not only does this put you and your family at risk, it poses a serious legal liability concern. In most cases, the technician will make you aware of the issue in writing and remove the equipment from service.

In recent years, there has been increasing news of contractors who scam customers into this situation. They may present to the customer that the heat exchanger has failed which scares the customer into making a costly furnace purchase. Other technicians may simply lack the training or skills to correctly diagnose a defective heat exchanger. Here are some following tips if you ever run into this situation:

• Always get a 2nd opinion. This ensures that you are getting another set of eyes on your equipment.
• Ask the technician how they found the problem. Problems can only be determined through advanced testing, or by disassembling the furnace and performing a thorough inspection. The technician should be able to explain how they found their diagnosis.
• Advanced testing includes:
  • Combustion Analysis
  • Salt test
  • Lighting
  • Dyes
  • Pressure

Heat Exchanger Failure Options

If your system has failed, here are some options that you may have to get you back up and going. For highest efficiency furnaces, the heat exchanger can be replaced. It is slightly less expensive than a brand-new system. Bear in mind that if the problems that caused the furnace to fail were not corrected, then the new heat exchange is set up for failure. Total system replacement is another option. It is a more expensive route, but with a total system replacement you benefit from a new warranty and at this point the contractor has the opportunity to remedy some system issues that contributed to the first failed heat exchanger.

Air Doctors Heating and Cooling, LLC are a fully licensed and insured heating and air conditioning company that serves most Southeast Michigan municipalities. Our staff is fully certified and pre-screened to provide our customers with a safe and satisfying experience. With over 100 years of combined industry experience, we take pride in solving all of your comfort needs. We are a family-based business that has been providing quality service to our neighbors for over 40 years. Contact us today to get started.