How to know if you’re getting the right air filter
The right air filter is all about the ratings. The Minimum Efficiency Reporting Value (MERV) is the scale for rating air filters. MERV is a porousness scale that goes from 1 to 16, with most home air filters ranging from 4 to 13 MERV. The higher the MERV, the more effective in removing contaminants from the air. In most homes, a MERV rating 8 is sufficient to reduce allergens at home without putting undue pressure on your filtration system. Here’s a breakdown of 4 common household air filters.
SPUN FIBERGLASS FILTERS (1-4 MERV)
Cheap and disposable, these filter out large particles to protect your system’s components and provide maximum air flow, but don’t filter out tiny contaminants. If you’re renting and don’t have allergy problems, this is the right air filter for you.
DISPOSABLE PLEATED PAPER OR POLYESTER FILTERS (5-8 MERV)
These are more expensive that spun fiberglass but they do a better job of filtering. These trap 80 to 95 percent of the particles 5 microns and larger. Pleated filters are made up of folded sheets of cotton or polyester-blend fabric. They fold like an accordion, fitting more fabric surface into a smaller area. Because of this, these filters are often high efficiency; to promote better air flow, look for one with lots of pleats. The more pleats it has, the more easily air can pass through this filter. So a pleated polyester filter with a MERV value of 6 to 8 may be the right air filter solution. It removes many pollutants from your home without taxing your HVAC system.
DISPOSABLE ELECTROSTATIC FILTERS
Electrostatic filters can have MERV values of 10 or greater. They’re very effective at decontaminating the air inside a home. They contain multiple layers of polyester-blend materials framed by a polyester mesh. These filters create their own static charge. As air passes through the positively-charged outer material, it transfers the charge to the particulate matter. Consequently, the charged particulate matter is attracted to the negatively-charged inner material, and sticks to it.
Electrostatic filters trap all kinds of particles, including mold and pollen. Smokers or people with allergies or asthma may find this to be the right air filter types. However, disposable electrostatic filters can be on the pricey side. They may overtax your HVAC system if it can’t handle the limited airflow.
WASHABLE ELECTROSTATIC FILTERS
These filters are framed in aluminum, cased in aluminum mesh, and made of washable material. Their average price is around $20, and you only have to replace them every 3-5 years. To maximize their effectiveness, you need to wash these filters every three months or so.
There is some debate as to whether washable filters actually live up to the hype. They can have MERV ratings of 10 or greater, but they aren’t always high efficiency, and it’s sometimes difficult to tell the difference. Often, mold and bacteria grow when they aren’t completely dry. They can also bend, warp, or break during washing. If you think washable filters may be the right air filter for you, be sure to check its MERV rating, clean it regularly and dry it thoroughly.
The Environmental Protection Agency suggests consumers contact an HVAC technician to determine the right air filter for their systems. Remember, an air filter serves two purposes: to clean your air, and to protect your HVAC system from damaging particles. Keep both in mind when you’re deciding which air filter to buy. If you have questions, feel free to contact us for answers.