We install AC units and furnaces for both comfort and health. Both of these, as well as your bank account, can be negatively affected if you make the wrong filter choice for your air conditioning unit or furnace. Here are some helpful tips to help you make the right choice when selecting a home, furnace, or HVAC filter.

Research by the EPA (Environmental Protection Agency) states that Americans spend up to 90% of their time indoors. Indoor air quality is affected by your home filter and should be a priority for your health.


Get the Correct Type of Filter

Filter type selection is the first important detail you need to consider. A home air filter is a physical filtration medium that will trap all sorts of airborne particles you don’t want in your home. 

There are many filter types and they use different materials or substrates to filter the air that flows through the filter. Similar to masks that could be made from paper or different fabrics.


Your choice of  filter types will include:


Fiberglass Filters

These will be your cheapest option. They also have the lowest efficiency in filtering out particles from the air. They usually filter less than 10% of particles. These filters are designed to protect your AC unit and not to improve air quality in your home. 


Pleated Filters

Manufactured from cotton or polyester and have pleated folds to increase the surface area. More pleats mean more surface area for filtration. These are recommended for home installations. They will improve air quality in your home by filtering particles like smoke, dust, and other pollutants. 


Washable Filters

These, as the name suggests are washable. They are expensive to initially buy. They can be cost-effective in the long run as they can be washed and replaced in the unit. You will be washing them regularly and they could become less efficient and clogged over time. You also need to make sure they are thoroughly cleaned as these filters trap all the particles you don’t want in your home. 


Electrostatic Filters

Electrostatic filters are statically charged filters that attract dust and articles due to the electrostatic charge. Similar to your hair in science class that stuck to the balloon that was statically charged. 


  • HEPA Filters
  • UV Filters


UV filters work in addition to a physical filtration system as they don’t filter any particles. They only kill living organisms like viruses and bacteria by exposing them to UV light.

You will also have to consider that not all filter types will work on your unit. As an example, a fiberglass filter will be easy to replace with a better-performing pleated filter as they both mechanically trap particles and come in the same size. It will most likely not be possible to replace your current fiberglass filter with a UV filter as these are specialized filters that use electricity to work. Your HVAC unit will have to be replaced or retrofitted to work with these types of filters specifically.


Know What Filter Rating you Need

Filters are classified according to MERV 1 to MERV 20. The lower numbers have less filtration efficiency and the higher numbers are more efficient. 


  • MERV1-6 is just protecting your HVAC unit from debris that could damage it. 
  • MERV 7-13 filters most particles like dust and smoke and is recommended for home use. These will trap particles as small as 1 micron. These filters trap 85 to 98% of airborne particles.
  • MERV 14-16 are high-efficiency filters recommended for industrial and commercial use like restaurants and hospitals. These filters will trap particles as small as 0.3 microns. These filters are also what you should look at if you have allergies or respiratory problems.
  • MERV 17-20 or HEPA filters are extremely efficient filters for specialized and commercial systems. These filters are 99.97% efficient and will trap particles even smaller than MERV 16 filters.


Remember that lower MERV numbers will mean that the airflow through the filter is higher. Higher airflow means lower utility bills and the AC unit is not working as hard. Higher MERV numbers mean that the filter will also restrict the airflow a lot more. 

Think about breathing through a cloth mask versus breathing through an N95 medical mask. Your AC unit needs to be designed specifically to work with filters in the MERV 14-20 range as they can be damaged if overworked due to reduced airflow. In a 2020 article by Stefanie Waldek in The Washington Post she also warns against going too far with MERV ratings when selecting a filter.

You will need to speak to an HVAC specialist if you have medical conditions or requirements for a filter in the range MERV 14-20 as most home units are not designed to use these.


Get the Size Correct

Make sure you measure the filter in your unit correctly. Length width and height will be needed. Measure in inches and round up to the nearest inch to get the nominal size. There is a handy guide to the correct sizing of filters on filterbuy.com so, after determining the nominal size it is easy to order the correct filter for your HVAC unit.

Replace Filters at the Correct Time

Some AC units will shut down when the airflow through the filter drops. This is an indication that your filter has become clogged with trapped particles. Other AC units will just lose efficiency, work harder, and may result in damage to the unit and high electricity bills. You might also find that your AC unit starts dripping water. When your AC is in cooling mode and the airflow is too low water will condense in the unit. Make sure to replace filters often enough before this happens. Follow the manufacturer’s advice or check filters regularly.

Buying a good new home filter can have implications for your health, the longevity of your HVAC system, and your utility bills. In most home use cases, the best option is going for a pleated filter with a MERV 7-13 rating and replacing the filter as often as needed.