What is a Good Air Conditioning/Furnace Filter?

Your air conditioner as well as your furnace are one of the most expensive appliances in your home today. Purchasing a new one may set you back five or even ten-thousand dollars. It is obvious that with this kind of investment that you want to take the proper care of your system so that you can get the most bang for your buck and that your air conditioner and furnace will last as long as they can.

One the simplest and most effective ways to maintain your air conditioner and your furnace is by regularly replacing or cleaning your filter. It can be easy to forget to do this, but if you keep up on it every few months then you are not only guaranteeing cleaner air for you and your family but you are also creating a more efficient system. The more efficient the system the less it has to do work and the less chances there are of failures.

Now if you are like me, or like I used to be, then when it came time to replace your filter you would run down to either the local hardware store, or even a grocery store, and pick up any filter that met the size requirements you needed. While this way does get you a new filter in the size you need it does not factor in quality.

This is where you’ll need to make a decision. If you are worried about allergens, pet hair, or other particles flowing throughout your home then it may be worth your time to invest in a higher quality filter. This holds especially true if you have someone in your house that has breathing problems such as asthma or severe allergies. Investing in the right filter can improve things substantially for them.

Air Filter Quality

I want to take some time now and go over the various qualities of air conditioner/furnace filters that are out there. Once you understand how quality works you can then make an educated decision on what filter you want for your home.

To understand the varying qualities of air conditioner filters you first need to understand the ‘MERV’ scale. The MERV scale, also known as Minimum Efficiency Reporting Value, is based on the percentage of particles from 0.3 to 10 microns in size that are filtered out of your system. The higher the MERV number on your filter then the better your air quality will be. Along with the MERV rating there is another measurement known as MPR or Microparticle Performance Rating. This MPR scale measures very small particles between 0.3 and 1.0 microns. Just like with MERV, the higher the MPR number the smaller the items that are filtered.

There are a variety of MERV sized air filters. To give you an example of the range let’s take a look below:

  • MERV One Through Four Filters – These are your lower end models that you’ll find in most grocery stores. While they do provide you with a filter, it is only the bare minimum. They can trap pollen and mold spores, but not near as well as higher rated filters. They are rated to remove particles over ten microns in size.
  • MERV Five Through Eight Filters – This is the next step up and will allow you to see a noticeable difference from the previous rung. These filters will allow you to remove agitants up to three microns in size. This would cover your pollen and mold spores as well as certain types of bacteria.
  • MERV Nine Through Twelve Filters – Now we’re getting into the higher quality air filters. These filters are rated to remove particles as low as one micron in size.  This could include such things as human hair, dust, pollen, mold, and combustion particles from candles or indoor fireplaces.
  • MERV Thirteen Through Sixteen Filters – Ok, folks this is the highest of the high for residential air conditioning and heating. With this rating we can get as low as point three microns. This covers nearly everything that there is including cooking smoke, paint pigments, fungal spores, and so much more.
  • MERV Seventeen Through Twenty Filters – I mentioned that the above was the best it could get for home air conditioning. Well, that was correct. However, this MERV measurement of seventeen through twenty is the absolute best possible and is typically reserved for medical applications such as hospitals and doctor’s offices. These filters are known as HEPA filters and are rated to remove up to 99.97% of particles that are point three microns or larger. These cannot be used in a traditional home air conditioner though due to the increased strain the system would go through pushing air through the filter. In some cases HEPA filters can be used in the home but only after extensive modification to the HVAC system.

Now, after reading this you may wonder what the right filter is for you. In most cases I would recommend the MERV nine through twelve categories. This gives you a high quality filter and will provide you with clean air throughout your home. If you have a family member, or if you yourself, struggle with asthma or other allergies then you may consider the MERV thirteen through sixteen filters. In extreme cases a HEPA filter and system may be needed, but this can get quite expensive as you will have to get a non-traditional residential air conditioning system to support the HEPA filter.

If you find that you are a little overwhelmed with all of the choices out there then you can check out our ‘Best Air Conditioner Filter’ guide. This guide goes through our recommended air filters in an easy to read ‘Good, Better, and Best’ category.