Top 5 Reasons HVAC Coils Prematurely Fail

by Matt Jacobs, December 4, 2017

  • Water Coil CorrosionCoil Plugging: If you are not changing filters and/or your HVAC coils are not cleaned properly in a timely manner, your coil will actually begin to act as a filter. When dirt builds up on the coil, the blockage prevents heat transfer and can cause an approximate 20% to 40% drop in performance. Dirt adds to the coil resistance and can be a primary cause for your coil to fail prematurely.
  • Vibration: When your HVAC coils are installed near a moving piece of equipment, vibration can occur and cause leaks. You can tell if vibration is the main cause if leaks are near the tube sheet and look like they are slicing through the tube. If/when that happens the coils should be isolated from the rest of the system to prevent vibration from causing damage. One way to combat this is by oversizing the tubesheet holes, but many manufacturers will not do this. Condenser Coils are usually the most common victims of vibration.
  • Corrosive Environment: This applies to both the air in the environment and inside the tubes. For instance, if there is a corrosive element in the air, it will eat away at the copper tubes, whether you have 0.020” wall or 0.049” wall. This is very common in areas where there may be salt in the air. To keep the costs down from going to a stainless steel or cupro-nickel coil, we usually suggest coating the HVAC coils. Coatings are almost always within the budget and only add about a week to the lead time. Steam condensate and untreated water can cause corrosion within the tubes of HVAC coils as well. If you have a steam coil that has failed before the one year warranty, there’s a great chance corrosive agents are in the steam and it’s eating away at the copper tubes.
  • Freeze-Ups: Most people think that when HVAC coils freeze, the water or condensate laying in the coil freezes into ice and it expands causing the tubes to bulge and eventually spring leaks. What really happens is the coil will freeze in multiple areas simultaneously and it’s the pressure between these areas that cause the tubes to swell and eventually burst. These are very easy to spot as the leaks will run the length of the tube rather than around the tube.  And be very careful when considering “freeze proof” coils.  If you remove 5-6 inches from the fin length to make it fit, the coil performance will suffer considerably. 
  • System Design: You would be amazed how many HVAC coils were never properly designed for their systems. If there was a problem with design, replacing the coil will only duplicate the problem. A high percentage of all our projects were because the HVAC coils were built incorrectly or was never designed right in the first place. Sometimes, owners want to improve performance by adding a couple rows, but don’t take into consideration the air pressure drop or fluid pressure drop that comes with it.

When dealing with a HVAC coil manufacturer, partner up with one who will walk you through the engineering and explain it along the way. Capital Coil & Air has well over a decade of experience and has seen every issue to make sure your everything from the quote to the installation go smoothly. Give us a call on your next project!


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