An example of a heat exchanger

An example of a heat exchanger

In the cold winter months of Chicago furnaces may run for 4- 6 months before they can even think about being shut off.  This can pose serious issues when a crack is found in a furnace heat exchanger.  This was exactly the case at the Mundelein home inspection.  Manufacturers generally recommend replacement of furnaces between the ages of 15- 25 years.  The condition of a furnace in 20-25 years depends on the care that was taken on the furnace as it aged.  If general maintenance is not performed on a regular basis (every year) then the furnace may not last 25 years.  The Rheem furnace found at the Mundelein home inspection was 26 years old and looked like it went through a war.  I’ve seen furnaces that were 5 years old that looked this way generally due to poor conditioning.  The housing on this particular furnace was in poor shape.  Rust on the furnace frame was evident throughout.  This was just the beginning.  When I opened the burner box I found that the burners, heat exchanger faceplate and the heat exchanger were all severely rusted.    This immediately made me nervous because if there is a crack in the heat exchanger there can be potential issues with carbon monoxide in the home.  Carbon monoxide in a home can cause issues that can cause dizziness, vomiting and even death.  The face plate was thoroughly inspected and no visible cracks were noted.  Cracks in a face plate on a heat exchanger can allow issues with carbon monoxide to enter the homes living area.  The furnace from the Mundelein home inspection looked to be safe to the eye.

Heat exchangers cannot be seen completely to the naked eye and require the use of a borescope. The furnace at the Mundelein home inspection would require a borescope to review the heat exchanger.  Unfortunately, out of the 5 heat exchangers there were 2 cracks found deep in the in the 2 center heat exchangers.  The cracks could not be seen from the exterior of the furnace and were only visible with a borescope.  The cracks seemed to be caused from high humidity in the basement that caused the rust to develop on the seams of the heat exchanger.  A carbon monoxide test was performed and there was no evidence of carbon monoxide issues in the home during the home inspection.  The concern is that the cracks can become larger allowing carbon monoxide in the home at a later time.  Anytime a crack is found in a heat exchanger it is recommended that a licensed heating contractor to be acquired to determine if the furnace is salvageable.  My personal opinion is the furnace is a huge safety issue and should be replaced immediately.  My clients from the Mundelein home inspection felt the same way but wanted to know why the heat exchanger rusted so badly.  There are many reasons for a heat exchanger to rust that you can look for and prevent in your home.

  • High humidity ~ Humidity in basements in known to be higher than any other area in the home because the basement is below the grade or earth.  The fact that the basement is below the earth raises the humidity and will require adding a dehumidifier in the basement to reduce the humidity to prevent rusting of the heat exchanger and the burner on the water heater.  The humidity was extremely high in the basement of the Mundelein home inspection and would recommend that a dehumidifier was added to the utility room to assist is removal of the humidity.
  • Leaking condensate lines from air conditioning a coils ~ Leaking or overfilled a coil pans or waste lines allow water to drip on the burners that may add the moisture to the heat exchanger causing premature rusting that can lead to cracks in the heat exchanger.  Any leaking piping above the burners of a furnace should be repaired immediately to assure damage does not occur to the furnace components.
  • Unlined furnace or water heater flues ~ unlined furnace and water heater flues can cause condensation roll back that may find its way back to the heat exchanger that can cause cracks in the heat exchanger.  This is a common issue that we see in over 75% of the homes we inspect.  This was the one of the reason the heat exchanger cracked on the furnace of the Mundelein home inspection.
  • Humidifiers set to high ~Humidifiers in most homes we inspect are set to high and are known to cause issues with high humidity in not only basements but the entire home.  Again, this was the one of the causes of the rusted heat exchanger on the furnace at the Mundelein home inspection.

As you can see there are things you can do as a homeowner to prevent damage to your furnace to assure a longer safer lifespan for your furnace.  Performing the check list above may prevent a damaged furnace and potentially issues with carbon monoxide in your home.

If you have any questions about furnaces you can contact us at The Thermal Home Inspector or 312-961-4228.

Thank you for stopping by and stay safe.

Jim Kolke

Pinnacle Property Inspection Services, Inc.