Tag: fouled hvac coils

Technical Corner: Tips for Cleaning Dirty Air Conditioner Coils

It is difficult to clean HVAC coils effectively due in part to coil design.  For multiple row coils, the copper tubing is staggered, and this prevents a stream of water from entering into the coils too deeply.  Usually the water velocity penetrates only the first few inches of a coil to loosen deposits.

Fouled coils lead to increased pressure drop across the coils. When pressure drop increases, more fan horsepower is required. This in turn draws more power, resulting in greater current consumption.

Pressure drop measurements across the coil when it is new are a valuable base line for performance.  Differential pressure that increases by more than one and a half to two times for sure indicates problems with coil cleanliness.

Cleaning coils also plays an important part in air quality.

Here are some rules to follow in cleaning coils:

1)Hot water always works better than cold water when it comes to cleaning.

2)Foaming cleaners, such as our product Instant Powder Keg, are generally better than non-foaming cleaners to remove biofilm and other deposits.

3)Certain areas of the coil may have more deposition than other areas.  A gentle flush of water through the coil may identify areas that are particularly fouled.

4)Cleaning from the bottom of the coil to the top is recommended. Multiple cleanings of the coil may be necessary due to heavy deposition.

5)After completion of cleaning, again run the hose through the coil to see if water now flows freely through areas previously found to be restricted.

6)Coil cleaners may be either acid, neutral, or alkaline in nature.  Many manufacturers call neutral pH or alkaline pH cleaners “non-acid” cleaners. Both acid and alkaline cleaners will attack coil fins, causing pitting and other corrosion. To reduce this problem, coils must be copiously rinsed with water to neutralize any chemical residual left on them.

7)Sanitize the coils using an iodine-based anti-microbial.

8)Apply a molecular coating to the coils, such as our product First Strike Micro Coat, to reduce future build up.

Properly cleaning coils as part of a preventative HVAC maintenance program can save a building owner thousands of dollars.

Lynn Burkhart is the founder and president of Controlled Release Technologies, Inc. located in Shelby, North Carolina. More information about the company, and its products, can be found at http://www.cleanac.com and by calling (800) 766-9057.

Technical Corner:How Professionals Work Smarter Not Harder on HVAC …. Part 2

Proper maintenance of HVAC air handlers helps the CFO or finance head, as well as occupants.   Saving money every month by getting the same amount of cooling for less money makes sense.  Certainly, if another provider of electricity came by the office and offered a 10% discount on electricity purchased by them, any owner would jump on the opportunity.

The reason why maintaining coils properly isn’t done is only because management does not realize the extent of funds they are currently wasting by cutting back on man-power for coil cleaning.  If it appears that it is too time-consuming, then other more technological methods developed over the past decade need to be looked at.

In our previous blog, we talked about how biofilms form on surfaces. Biofilms are interesting, mostly because they seldom are noticed and the average person is just unaware of them.

Indeed, they form on almost all surfaces and are not unique to HVAC interiors.

HVAC interiors offer something that most surfaces don’t see however, and that is a temperature controlled environment with moisture, darkness, and a constant supply of nutrients  from small particles in the air being pushed across the coils in amounts of millions of cubic feet each day.

We explained how technical studies by ASHRAE show coils within one year of cleaning are responsible for up to 20% or more increased energy costs than newly cleaned coils.  Since the HVAC energy use accounts for over 50% of a typical buildings electrical expenditures,  having clean coils would make for a much better bottom line in terms of energy usage.

But coil cleaning to remove the physical buildup of dirt and other contaminants may not make sense if manpower is on short supply, and it isn’t worth it, even with spending more energy dollars, to clean the coils often.   But there is a solution.

As most of you know, Controlled Release Technologies spends tens of thousands each year on research and development.  Since our founding in 1986 we have brought out more than a dozen innovative products that the marketplace had no access to prior to our development.  A major accomplishment was our development of First Strike MicroCoat ®.

First Strike MicroCoat ® keeps coils continuously clean for a year or more at a time without maintenance intervention or cleaning.   It was, and is today, a major breakthrough in technology.  We developed this product to handle concerns by many of our customers over odor control, and especially wasted energy they saw by using dirty insulated coils.

Another of your advantages with tis product is  it is water-based and  free of noxious petroleum products.   This makes it more environmentally se to use while at the same time being significantly more cost effective by removing extra labor for cleaning while decreasing your monthly energy bill.

Please do not hesitate to leave your comments or testimonials below.

Lynn Burkhart is the founder and president of Controlled Release Technologies, Inc. located in Shelby, North Carolina. More information about the company, and its products, can be found at http://www.cleanac.com and by calling (800) 766-9057.

Technical Corner: How Professionals Work Smarter Not Harder on HVAC …. Part I

Maintaining HVAC air handlers to obtain low cost of operations can be quite time consuming and use up available man-hours.  Management allocation of labor has always been minimal over the past few decades, but now restraints on hiring have been even more noticeable.  The result?

Many departments have cut back on necessary coil cleaning, keeping water collection pans free of bacteria and other microbials, and in some cases choosing to put off changing air filters.   While on the surface these things seem okay to cut back on, the actual fact is they cause more problems than they solve.  Of course the cutbacks seem to provide the owner with more cash flow.  But this is surely not the case.

Cutting back on maintenance items as above costs management more money rather than less.


A recent ASHRAE Journal reported a study that was completed in New York on HVAC units that had been cleaned a year previous.  What they found was to some surprising; others in the HVAC field might have considered the ASHRAE findings intuitive or expected.

Several air handlers had their coils cleaned after a one-year period.  The study found that the clean coils exhibited an energy savings of up to 20% or more than those coils that had been cleaned only one year before.   For several air handlers, this amounts to wasted financial expenditures of tens of thousands per year.   Balance that against keeping the coils clean throughout the year and one can see that saving a few man-hours does not really compare to this kind of wasted money.

The main culprit is biofilms.   Biofilms are very thin layers, in most instances, of bacteria and other microbes.  They tend to be sticky.   They grow on any surface, and growth is enhanced by the presence of high moisture and nutrients.

Because they are sticky, when any dirt or organic matter bypasses the filter or comes through the filter, the matter impacts upon the biofilms and may stick to the film.   Since the overwhelming amount of surface area is the cooling and heating coils, particles that impact and stick on the biofilms on these surfaces insulates the coils even further.   It is known that biofilms alone provide the same insulating affect as 5 times that amount of scale.

This is why coils that are apparently “clean” are financial detriments.  Knowing this, is it really smart to cut back on spending an hour or so cleaning coils?

But that is really only the start of the issues.   We all know bacteria and fungus create VOC’s or odors.  In many cases, these can be quite obnoxious.   Most managers might believe that since the air handlers are out of sight of tenants, no one really cares if they are in fairly good health.   We know of one air handler right now in the North East whose tenants in the building (lawyers by the way) have been complaining of odors for quite a few months.

Not withstanding all of the above, there lies another problem, and that is equipment sustainability.  How does having a clean HVAC unit related to the expected lifespan of the unit?  Most air handlers may cost anywhere from $25,000 to well over $100,000 to replace.   In the vast majority of cases, the owner does not hear this news until the unit is within a few weeks or months of replacement.   This can come about by the management not periodically inspecting the units for corrosion and fouled coils.

In the next blog, handling the above in a realistic way that makes sense will be reviewed. Please feel free to comment, we love to hear from our readers.

Lynn Burkhart is the founder and president of Controlled Release Technologies, Inc. located in Shelby, North Carolina. More information about the company, and its products, can be found at http://www.cleanac.com and by calling (800) 766-9057.