AC Filter MERV RatingsJuly 07, 2020
MERV ratings are assigned to air filters based on the size of particles they allow through them. At Dallas Air Duct Cleaning we recommend air filters that have a MERV rating between 8 and 13 for most homes with central air conditioning.
MERV rating or the Minimum Efficiency Reporting Value, is a system used to evaluate the efficiency of an air filter based on how effective it is at catching particles of varying sizes. Along with MERV rating comes pressure drop, this is the downside to high MERV filters. Pressure drop is the resistance of air going into your air system. Your air filter is a barrier between your home’s cooling system and the vents in your home, meaning that it could potentially slow the ability of air to get pulled into your system.
Choosing the right filter with the proper MERV rating is important to keep your home and air cooling system functioning efficiently. However, as filters catch the undesirable particles, they become clogged and in turn have a higher pressure drop. It is important to replace your filters regularly so to not negatively affect your home’s cooling system. Here’s a breakdown of the MERV ratings to help you make a good decision for your home.
MERV 1 - 4 : minimal pressure drop, capture about 20% of large particles...they are like using a dirty sock for a filter.
MERV 5 - 7 : some pressure drop, but minimal, capture between 20% - 69% of large particles...not awesome, but not a dirty sock. Maybe a clean sock as a filter
MERV 8 - 13 : some pressure drop, captures 85% of large particles and 50% of small particles. Meaning it can filter out small particles like unwanted germs and all the dander and bacteria found in your air while still having a lower pressure drop making them ideal for most homes.
MERV 15 - 17 : quite a bit of pressure drop, captures more than 90% of large particles and between 70% - 90% of small particles. These can be helpful for people who are immunocompromised but due to their pressure drop, they can negatively affect your AC’s efficiency.
MERV 18 - 20 : highly effective at filtering out small particles, increased pressure drop. Usually found in commercial systems that are not as easily affected by pressure drop but that are in sensitive areas such as surgical rooms in hospitals and nuclear power plants.