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MERV Ratings – Choosing the Right Air Filter

merv ratings - air filters
Reading Time: 3 minutes

I know the first thing you want to know is what’s a MERV rating? MERV stands for Minimum Efficiency Reporting Value and it is the system used to measure how efficient air filters operate. You will find MERV ratings ranging from 1 through 20 and the higher the number the better performance that particular air filtration device will deliver. ASHRAE (American Society of Heating, Refrigerating and Air Conditioning Engineers) came up with the MERV system in 1987 to help eliminate confusion when it comes to air filters. On a side note, has anyone other than me noticed that there are a ton of acronyms in the HVAC (Heating, Ventilation and Air Conditioning) trade?

First a couple of thoughts on filters… Most generic, over-the-counter filters are just that, they are not air cleaners. The actual main purpose of the filter on your air conditioner is to help keep the equipment clean vs. actually cleaning the air. Considering 1/32” of dust on an air conditioners blower wheel can reduce its efficiency by thirty percent, keeping the air conditioner in your home as clean as possible is of paramount importance.

The next thing to take a look at is what size particle the filter is achieving the MERV rating at. The general industry standard is one micron. Let’s put that in perspective for a second as a typical human hair is right around 30 microns in diameter, so we are dealing with some pretty small stuff here. The typical MERV 8 or 9 filter is better than 75% effective at removing particulates one micron and larger and will do a good job keeping the air conditioner as dirt free as possible. If you have furry friends as part of your family you may want to look to increase the MERV rating to around 13 to achieve the desired level of clean.

When you start talking about MERV ratings of 16 and higher, now you are actually shifting into a realm of cleaning the air vs. just filtering. We feature the IQAir Perfect 16 filter when you are looking for the best possible air quality in your home or office. The 16 of course stands for its MERV rating and it has been shown to be 99.9% effective at removing particulates as small as .003 microns. At that size we are talking about things like viruses, bacteria and smoke. The one drawback to the IQ system is its size, the box is a little larger than two by three feet and clocks in at about two feet tall so you need to have some room in the attic or on air conditioner to make it fit.

Don’t forget, if you are looking to improve air quality in the home make sure that the duct system is well sealed, otherwise as I have told you in the past, you will be bypassing the filter with contaminated air from the attic.

The last thing to check on, and this will require the help of yours truly or another air conditioner professional with a manometer, the static pressure that the filter is creating within the duct system. If the filter is too dense and is raising the static pressure on the unit you could suffer from higher utility bills or premature equipment failure. If you want to know a little more about static pressures, check out my article on that here.

I’m being told there is an AC system in Boca that needs my attention, so until next week, did you hear about the guy that swallowed the bottle of food coloring? He told his doctor he felt like he dyed a little on the inside.

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