When looking for ways to keep your home’s HVAC system running smoothly, maintaining your furnace, AC or heat pump’s air filter should be at the top of your list. In addition to saving on energy, selecting the right filter for your home can prevent premature breakdowns of equipment and improve indoor air quality.

What is MERV 

Many homeowners do not realize that HVAC filters come in many different types and efficiency levels. MERV, or Minimum Efficiency Reporting Value, ratings provide insight into the effectiveness of an air filter. Using a scale of 1-16, with higher numbers representing the ability to screen out smaller particles, MERV ratings allow consumers to quickly identify the screening ability of a filter. MERV air filter ratings were designed by the American Society of Heating, Refrigerating and Air Conditioning Engineers to provide a standardized system for comparing filters.

It’s important to realize that just because a filter is rated high on the MERV scale, that it’s the best filter for your home. This is not always – or even usually – the case. Filters with MERV ratings higher than 12 tend to impede system airflow, requiring a contractor to retrofit your equipment to accommodate this denser, and usually larger, filter. The higher-rated filters can put undue pressure on your forced-air system, leading to premature breakdowns and reduced efficiency.

The air inside homes typically contains a wide range of contaminants, though an air filter with a MERV rating from 7-12 should be able to remove most of them. A filter within these parameters would be sufficient to filter out:

  • Pollen
  • Dust mites
  • Pet dander
  • Spores
  • Bacteria
  • Textile and carpet fibers
  • Cooking oil
  • Burning wood
  • Auto emissions
  • Insecticides
  • Tobacco smoke
  • Smog

The level of filtration above this range is typically only needed in sterile settings such as hospitals and laboratories.

The efficiency of a filter also has a direct effect on how often the filter needs to be changed. Filters with high Minimum Efficiency Reporting Values trap more particles while filtering air, and therefore, get clogged sooner. A clogged filter can have a detrimental effect on your HVAC system as well as decrease the air quality in your home.

Types of Filters

Understanding the difference between filters can make choosing a filter with the right MERV rating for your home  much easier:

  • Disposable fiberglass – These filters typically have MERV ratings of 1-4. They have the capability to prevent large particles from getting into your system. While disposable fiberglass filters are inexpensive, costing a couple of dollars at most, they won’t do much to improve indoor air quality.
  • Disposable pleated -– These popular filters are typically made from cotton or polyester and with the greater surface area as a result of  folds in the filter material, can remove smaller particles from the air. With MERV ratings of 6-8, they do a good job of removing most of the unwanted particles, including allergens, from your home’s air.
  • Disposable electrostatic – These filters trap small particles on cotton or paper that has an electrostatic charge. They have MERV ratings of around 10. These filters are available in most standard sizes, but specialty sizes can be expensive. Due to the cleaning ability of these filters, they are good for homes with small children or pets.
  • Permanent electrostatic – With a MERV rating of 8, the permanent electrostatic filter is similar to the disposable version. These filters have a washable filter, which allows it to have a useful life between six and eight years.
  • High-efficiency pleated – The most expensive filter option, these filters have ratings of 14-16. They are relatively expensive, but have the ability to screen out even the smallest particulates. Hospitals and other institutions typically use this type of filter. They are much thicker than standard filters and require serious system modifications to work in a typical residential HVAC setup.

For additional information on MERV ratings and selecting the right furnace filter for your home, contact Pioneer Comfort Systems today.