Furnace Air Filters

Understanding Your Furnace Air Filter

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When you have a central furnace and air conditioning system, air quality often becomes an issue. These types of systems use duct work to transport air throughout your home. As one vent delivers the heated or cooled air to the room, another vent is drawing air into the duct work to be sent back to the furnace or air conditioner. The air in your home will cycle through the system at least 45 times or as much as 140 times a day, depending on how much you run your HVAC systems. Dust, dander, pollen, mold spores, and many other microscopic particles are being cycled along with the hot or cold air. This constant recycling of polluted air is often what leads to poor indoor air quality.

Your furnace and air conditioner should have an air filter as your homes first line of defense against these nasty particles. But, finding the right air filter for your home can become very frustrating once you find out how many choices you have. The four main types of air filters that are on the market for residential HVAC systems include:

  1. Media air filters
  2. Pleated air filters
  3. Electrostatic air filters
  4. HEPA air filters

But what makes one filter better than another? When you are filter shopping there are a few things you should be looking for:

  1. Efficiency when removing particles from the air- The higher the efficiency rating the better your air quality will be.
  2. Air flow restriction caused by the filter- The restriction of air flow causes the furnace and air conditioner to work less efficiently, and it can even choke the system causing a breakdown.
  3. Lifespan of the filter- The longer the lifespan, the less you have to change the filter.

Media air filters-

This type of filter uses pre-cut pads that fit into aluminum filter frames. The frame should last the life of the furnace and the pad can be easily removed and replaced whenever it gets dirty. Media filters are efficient because they can hold a very large amount of particles before they need to be changed. As the air passes through the filter, the particles that are not caught in the first layer of media have a good chance of being picked up by the proceeding layers of media. These filters can last around 3 months, but should be checked every 30 days just in case you have a particularly dusty month and need to replace it sooner. This type of filter should not restrict air flow in the system if it is replaced regularly.

Pleated air filters-

This type of filter is probably what you have in your furnace right now because it is one of the most popular filters in the residential market. Pleated air filters only have one layer of material, but it is pleated in order to increase its holding capacity. This type of filter is relatively efficient at removing particles from the air, but the efficiency really depends on the quality of the filter. Since there is only one layer of material, any particle that gets through is able to continue to circulate through the home. Some pleated filters are made out of materials that can capture a larger amount of particles. But the more efficient the filter is, the more it restricts air flow. Another problem with these filters is that they do not have a very long lifespan. Pleated filters should be changed monthly, or they will become clogged and restrict airflow into the furnace and air conditioner.

Electrostatic air filters-

This type of filter uses static electricity to remove dust and particles from the air. There are two types. The first is a non-electric electrostatic air filter. This filter is reusable over and over. All you have to do is wash it every two to three months. The other type is an electric electrostatic air filter. This type of filter plugs into a 110volt outlet, and you replace the pad inside it every one to two months. Both types of electrostatic filters are very efficient. The electric version is more efficient than the non- electric version however it does cost a great deal more. Both types can be found with efficiencies over 90% particle removal down to 1 micron. The truly great thing about this type of filter is that you do not have to sacrifice efficiency in order to maintain air flow. This type of filter will allow your HVAC systems to run as efficiently as possible.

HEPA air filters-

High Efficiency Particulate Air filters are the most efficient air filters when it comes to removing particles from the air and improving indoor air quality.  They are 99.97% efficient at removing all particles down to 3 microns. This grade of efficiency is used in hospitals to help create a sterile environment. They have the design of a pleated filter, but there are more pleats in a HEPA filter which allow you to change it less often. The HEPA filter is also made out of a different material than the pleated filters, and it is this material that allows these filters to capture so many particles. There is a downside though. These filters do restrict air flow more than electrostatic or media filters.

How do I know what works best for me?

In order to determine which filter is best for you, you need to look at the needs of your family. If you have family members who suffer from allergies or asthma, you may want to consider a more efficient filter. If your home already has an air cleaner installed, you may be OK just purchasing a pleated or media filter because your indoor air quality is already under control.

If you live in a home with chronic odor problems like those caused by pets, smoke, cooking, and garbage, you may want to pair your air filter with an activated carbon filter. This type of filter does not remove particles efficiently like the other air filters. When paired with a media filter or electrostatic air filter, you can remove both smells and harmful particles. It is not recommended that these filters be paired with pleated or HEPA filters because they will only further restrict the air flow into your systems.

Hopefully from this information you will able to find a filter that works best for your home and being to improve your indoor air quality.


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