Filters are an important part of your heating, ventilation and air conditioning system, but with so many choices, which one should you choose??

Opinions vary, depending and filters are all designed to meet a specific need. But the one thing all experts agree on is that a dirty HVAC filter hurts the unit’s energy efficiency! Not only will a dirty filter that restrics airflow cause the system to be overworked, reduce comfort levels, and cost more to operate, increase the pressures in the system, and lead to premature system failure.

To pick the right filter, you need to balance the amount of dirt the filter can remove while still allowing enough air to pass through your duct system. The minimum efficiency reporting value (MERV) rates their effectiveness on the size of dust/allergen partical they trap. The higher the rating, the more efficient they are at preventing dust from going through your system. However, with many systems in the Richmond area having return duct systems that are undersized it is important that you know exactly how much air is flowing through your duct system before considering using a high performance dust collection filter…otherwise you may risk shortening the life of your A/C system.

Feel free to call Comfort Keepers HVAC at 804-601-3035 and we will help you consider your options so you can pick what’s best for your home given your specific situation.

Fiberglass (the see through filters)

Fiberglass filters are the least expensive, and provide the most airflow, but also do little to improve the overall indoor air quality in your home. However, if changed monthly and not allowed to collect to much dust between changes, they do protect your HVAC unit from dust buildup. Most fiberglass filters usually have a MERV rating between 1 and 4. We will sometimes recommend these filters for HVAC systems that have significantly undersized duct systems in order to maintain the most airflow possible.

Polyester and Pleated Filters

Next on the cost scale are polyester and pleated filters. There are several different Merv Rated pleated filters, with most between an 8-13 MERV rating. These filters will typically remove up to 45 percent of the air pollutants in your home. Comfort Keepers HVAC stocks a Pleated Merv 8 filter for $6 each ($72 for a case of 12 each) should you need a source for a quality Merv 8 filter that doesn’t cause significant airflow restrictions. Once you get into the Merv 12+ range we definately recommend that homeowners have a professional to verify that their airflow is not being restricted by the use of the filter.

Washable Filters

We don’t recommend washable air filters. Most HVAC technicians agree that washable air filters are at the bottome of the list when it comes to filters…..They can be expensive and, have a low MERV rating (1-4) while requiring extensive maintenance that usually doesn’t get done.

Not only do they require lots of maintenance by homeowners, but they also are a breading ground for fungus and bacteria, which will migrate through your duct system and into your home.


High-efficiency HVAC filters can remove up to 85 percent of the air pollutants from a home, but they aren’t practical for most homes. They typically have a MERV rating of 14 to 16.

Often used by medical facilities and hospitals, they’re made from pleated filter paper or synthetic polyester fibers and they can trap very small particles of dust, pollen, mold and other irritants, but will significantly reduce airflow in most residential HVAC systems. Keep in mind that most filter companies are not interested in maintaining the required balance between airflow and fitler efficency….they just sell and market filters based on price and filter efficency alone.

To summarize, the best HVAC filter for your heating or air conditioning system might not be the one with the highest MERV rating, as you must balance filter efficency with aiflow. Use of an overly restrictive air filter (or having a dirty filter) can slow the rate of airflow, causing your unit to not operate properly, increase cost, and shorten it’s useful life. Regardless of the filter you are using, please make sure it is changed once you see a layer of dust on it! Some home may go 2-3 months between filter changes, but others only 4-6 weeks, as every home is unique.


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