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Cooper Mechanical Blog

The Lowdown on Choosing the Right Air Filter

Posted by: Cooper MechanicalThursday, July 07, 2016

Dirty Air Filter
Photo credit: Flickr user Ivy Dawned

Why Are Air Filters Important?

If you ask the average homeowner how frequently he or she changes the air filters, they will probably default to the common best practice of every 2-3 months. The reality is that without a gentle reminder to change them, many won’t replace filters until they begin to see the negative effects of old filters: dust clinging to vents or becoming more noticeable around furniture and appliances. 

Dirty filters are are bad for a number of reasons. They can prevent healthy air flow and circulation in your home, which can reduce the quality of air (it is dirtier) and make your air conditioning or heating system work harder to properly cool or heat your home. Overworking your HVAC system because of clogged vents can make your power bills more expensive and lead to future system problems. Moreover, a filthy filter can also negatively affect those who are prone to respiratory conditions like asthma or allergies. The bottom line: replace your filters before you begin to see the signs that they are dirty.

What Air Filter Should I Buy?

When it comes to choosing a filter, one should pay attention to more than just the proper size and cost. For most residential and commercial HVAC systems, a mechanical filter is most common. Mechanical filters use synthetic fibers to trap small particles, dust, debris and dirt, preventing them from being released back into the air you breath in your home.

When comparing air filters, which can range from a generic fiberglass filter in a cardboard frame for $1 to a true HEPA filter in the $25-range, the important thing to look for is the MERV rating. MERV stands for Minimum Efficiency Reporting Value, and this number corresponds to the effectiveness of the filter in trapping particles. Generally, the higher the MERV number, the smaller the particle the filter will catch. Below are some common air filter types with corresponding MERV ratings:

Fiberglass Air Filters: These are the cheap $1-2 filters you’ve likely seen before. While their cost is attractive, their MERV rating in between 1-4, and they remove less than 10% of the air pollutants in your home. While cheap, these filters will need to be replaced more frequently, and are not advised if you are prone to respiratory issues or allergies.

Pleated Air Filters: These filters have pleats, corrugated-like grooves that make them more effective at trapping all the debris you don’t want floating in your air. With a MERV rating between 10-13, these filters can remove up to 45% of air pollutants, making them much more effective than your $1 fiberglass filter. Pleated filters are generally cost more (around $10), but are more effective. If you see different kinds of pleated filters, look for the MERV rating or number of pleats. The more pleats, the better the filter.

High Efficiency Air Filters: Not to be confused with HEPA filters, HE air filters have a MERV rating between 14-16 and remove up to 85% of pollutants from your air. This filter uses finer polyester fibers and pleats to remove smaller particles than the other filters. These may be ideal should you suffer from allergies or just want peace of mind that small bacteria are not making it through your filter.

HEPA Filters: We’ve discussed HEPA before, but this is the best type of home filter you will find. A HEPA filter has a 17-20 MERV rating and removes up to 98% of air pollutants. It's important to note that a HEPA filter will need to be part of a whole house air filtration system or in a stand-alone filtration system. This makes it one of the most costly but also the most effective option. A HEPA filtration system is ideal for people with severe allergies and respiratory issues. 

In conclusion, the higher the MERV rating, the more effective the filter. A higher MERV score also means that you will not need to change the filter as frequently, so consider some of the cost and time savings when deciding which filter is right for your home.

If you are in the Conway, Myrtle Beach or greater Grand Strand area and need assistance with your home or residential HVAC, electrical, or refrigeration systems, be sure to contact Cooper Mechanical Services.