The Art of the Filter Change

There was a time when changing A/C filters wasn’t considered rocket science, but over the past 15 years or so, I have come to realize there is so much more to it than previously thought. I know that the levels of sophistication for filters and filter change technology have existed for many years, and I’m realizing I was simply a late bloomer in “getting” this technology.

More and more, there are requirements for our departments to provide our campuses a safer and healthier living, working, and learning environment. Studies performed by ASHRAE (ASHRAE Journal, Oct. 2006) link student performance to IAQ conditions. It is up to us to ensure our customers’ physical needs are met as it relates to indoor air quality, as well as many other things. IAQ has become a focus point for our customers, and we must be sure we meet or exceed their expectations as well as those of organizations such as ASHRAE and even the EPA, both of whom provide design specifications and guidelines toward proper indoor air filtration. It is important to note that we should endeavor to meet or exceed these specifications and guidelines because we want to do the right thing by our institutions and our facilities’ occupants, not because someone is requiring us to do so.

Document the Equipment

We can start by ensuring that we know what equipment we have in the field. All these assets should be listed in our CMMS programs and each unit — be it air handler, fan coil, or PTAC (packaged terminal A/C) — should have its manufacturers’ recommended filter change information, i.e.: filter size and type, as well as recommended replacement frequency, entered into the system as an appropriate PM task. As PM tasks go, it is important to begin this process by ensuring that our A/C system coils are clean and free of obstruction due to dirt, dust, debris, pollen, mold/mildew, dander, and other allergens. This creates a more efficient process, as air moves more easily across the filters and the coils, thus allowing maximum airflow and using less energy due to the fan not needing to work as hard.

Filter Options
There are many filter options available. Filter efficiency is measured in MERV (Minimum Efficiency Reporting Value) ratings, from 1, which allows particles greater than 10 micrometers to pass, to 16, blocking particles as small as 0.03 micrometers. The options begin with roll media as well as framed fiberglass filters, which generally range from 1 to 6 in the MERV ratings. They continue with high-efficiency pleated filters with MERVs in the 6 to 12 range, and on through electrostatic and HEPA filters capturing down to 0.03 microns at a MERV 16 rating.

The available technology is vast and, like many things, in filters, you get what you pay for. A good high-efficiency pleated filter will allow more air to pass through it and will trap more dust and pollutants over a longer course of time. Take the time to carefully match the proper type and size of filter to the units they will serve and document this in your CMMS program, as well as any other inventory control system or program you may have.

As I refer to filter changes, I am thinking in general terms of air handlers and fan coil type units. There are a number of other filters on campus that require changing. There are filters in chemical fume hoods, as well as laminar flow hoods. When changing filters in these units, proper disposal procedures must come in to play. A waste determination will need to be performed prior to handling and disposing of these filters. If the waste determination notes the presence of enough trace chemical in the filter media, then it must be disposed of in accordance with the appropriate federal, state, and local laws governing hazardous waste disposal.

To Be Continued…

Stay tuned for the October issue, where we will continue this column. In that portion, I will get into the meat of the topic, looking at who should do the filter replacements, the technology behind filter changes, and how often they should be replaced.

About the Author

Michael G. Steger is director, Physical Plant, for Berkeley Preparatory School in Tampa, FL. He can be reached at

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