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Northeast HVAC News Guest Column
Top 5 Reasons Commercial
HVAC Coils Prematurely Fail.
By Dan Jacobs
Capital
Coil & Air has come across virtually every scenario over the
years in which a commercial HVAC coil had to be prematurely
replaced, and we have since created an easy guide targeting the
main reasons HVAC Coils prematurely fail.
Coil Plugging: If you are not changing filters and/or
your commercial
HVAC coils are not properly cleaned in a timely manner, your
coil will actually begin to act as a filter. When dirt builds up
on the coil, that 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 coastal 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 your
budget, and its application will only add about a week to the
overall 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 that corrosive agents are in the steam,
and it’s eating away at the copper tubes.
Story continues below ↓
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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 that 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.
ALSO be very careful when considering “freeze-proof” coils!
If you remove 5-6 inches from the fin length to make the
“freeze-proof” application fit, your coil’s performance will suffer
considerably.
System Design: You would be amazed to learn how many HVAC
coils were never designed properly for their systems. If there is a
design problem, replacing the coil will only waste time and money;
while you have done nothing other than duplicate the previous
problem. A little known fact in the replacement market is that a
high percentage of all our projects are because the coils were built
incorrectly or were never designed correctly in the first place. In
some cases, owners attempt to improve the coil’s performance by
adding additional rows. Most however do this without taking into
account the air pressure drop or fluid pressure drop that comes with
it.
When dealing with an HVAC coil manufacturer, try to 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
can help you diagnose whatever problem that you are experiencing
correctly the first time.
Capital Coil & Air is
the leading manufacturer of commercial OEM HVAC replacement and
custom design/build booster coils, fan coils, condenser coils, and
DX Coils. We have over a decade of experience in the industry to
assist you and consult with you in your coil selection process. The
last name Jacobs has been an industry standard-bearer for more than
half of a century, and will continue to lead the way in the HVAC
manufacturing business for decades to come. For more information
visit
https://www.capitalcoil.com/
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