Air conditioning filter Frequently Asked Questions

Air conditioning filter

Air conditioning filter Frequently Asked Questions

What does MERV stand for?

MERV stands for Minimum Efficiency Reporting Value.

What is a HEPA Filter?

 HEPA stands for High Efficiency Particulate Accumulator. A HEPA filter has to meet US Department Of Energy requirements that are more stringent than those for high MERV air conditioning filters.

An air filter with a MERV range of 17-20 is a true HEPA filter. HEPA filters remove more than 99.97% of airborne particles that are more than 0.3u in diameter.

 How can I accurately measure the air flow through my air system and know if it supports efficiency?

Hire an air condition contractor or a home inspector and have him or her review the air flow rate of your air conditioning system using specialized equipment. Ask about the viability of installing a system that supports a slower air flow. Remember that when it comes to filtering anything, especially air and water, the slower the better.

What is an air filter made of and what makes it durable?   

A media air conditioning filter is made of synthetic media fibers that bacteria and microorganisms cannot process as food. This means that the filter does not get eaten up and decay.

  How frequently does an filter need to be changed?

 An air conditioning filter usually needs to be changed two times per year. However, its effectiveness can vary. Efficiency can reduce when there is a lot of pet dander, leaky duct work in the attic, smoking in the home, or sanding projects going on. It can also be reduced with continuous  operation of the fan or using the filter longer than its lifespan. In these cases, the filter should be changed more frequently in order to regain efficiency.

 What is the most practical MERV rating for a residential air filter?

MERV ratings range from 1 – 20. Low ratings are not going to do the job properly, and high ratings are going to require modifications to the air system. The most practical rating for a residential air filter is, therefore, in the MERV 5-13 range.

  Why can’t I go with a slightly higher MERV rating?

 An air filter that has a MERV rating of 14 and higher is termed a HEPA filter. It restricts air so much that it interferes with the running of the air conditioner. This requires a bi-pass modification to the system into which part of the air can be diverted to be  separately filtered before being reintroduced back into the main air stream. This costs money and a HEPA filter is also more expensive.

 Will a MERV 5 – 13 rated air filter do as good a job as a HEPA filter?

 Do not underestimate the efficiency of a good sub-HEPA filter. What you have to keep in mind is that this type of media air filter is capable of trapping 75% of the particles in the air. However, that happens on every circulation of increasingly more filtered air through the system and the air filter. The result is as much as 99% effectiveness, which is on par with HEPA filters.

 Which air filter supports air conditioning efficiency?

 Air flows easier through a low MERV rated air filter and therefore runs at peak efficiency. However, this is not for long, because insufficiently filtered air soon begins to clog up the evaporator coil, which makes the system less efficient. Air that flows through a high MERV rated filter is cleanest but restricts air flow to such an extent that the system runs inefficiently. The happy medium is an air filter which is rated MERV 5 – 13.

 Which air filter is the quietest?

 Air filters that are too compact or do not fit properly are the ones that usually  make a  noise. Choosing an air filter that is rated MERV 5 – 13, and which is properly fitted, is your best option for a quiet air filtering experience.

 When will an air-conditioning filter get clogged up and stop working?

As the air conditioning filter gets more clogged up, the efficiency of capturing particles increases. This is because pore openings decrease due to the particle buildup, which allows the air conditioning filter to capture more particles. However, this only works up to a point, as the energy efficiency of the system will decrease.

 How do I determine if the filter is working?

The duct side of the air conditioning filter should be gray and ‘ashy’ after a few months. If it is not dirty and a filter with low MERV rating is used, upgrade the air conditioning filter with a higher MERV rating.

Home air filters

Continue reading my Air Conditioning Filter Reviews including Best features, How they work, What makes them green, plus Tips and tricks. Please visit my Green Store and support Switch it Green, Switch it Forward.

Please see our other review posts for this living green product: 

Best features home air filters

How Air conditioning filters work

What makes a home air filter green

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