Which Furnace Filter Do I Buy?

Your choice in furnace filters can not only save you $$, but can improve the air quality in your home. There are several options when it comes to furnace filters. Your choice should be made based on how much you want to spend, what you're trying to filter out, and how diligent you are about changing your furnace filter.

Most filters will carry a MERV (minimum efficiency reporting value) rating, which indicates their effectiveness. MERV ratings range from 1 to 16. The higher the MERV rating, the more effective the filter.

MERV Rating

MERV Rating - Minimum Efficiency Reporting Value

All furnace filters have a MERV rating. These ratings are assigned to filters base on how effective the filter is on capturing particles of a sepcific size.

MERV ratings range from 1 to 16, with 1 being the least effecitive.

Below are five common filter options, available in sizes and prices.

Disposable Fiberglass Filters

This is the most common type of furnace filter. Crated from 1" thick spun fiberglass, it stops particles like dust, lint and litter from gathering inside your furnace. It is a good filter type for people with no signs of allergies or asthma. This filter has a MERV rating of 2 - 3.

Disposable Pleated Filter

These filters are made from polyester and cotton paper, this filter removes small particles like spores and mites. This filter is relatively inexpensive; however, it needs to be changed at least once per month to avoid clogging. Not changing the filter frequently enough could create an air flow struggle which will make your system more expensive to operate. This type of filter has a MERV rating of 5 - 6.

Permanent Electrostatic Filter

This type of filter uses self-charging electrostatic cotton or paper fibers and can attract extremely small particles. A safe static charge is produced by forcing air across the filter. In turn, this static charge attracts and traps particles in the filter. Permanent electrostatic filters have a removable, machine-washable filter that can last six to eight years. Electrostatic filters are more efficient then pleated, but can be fairly expensive. These filters have a MERV rating of 8 - 9.

Disposable Electrostatic Filters

These filters are similar to permanent electrostatic filters, also using self-charging cotton or paper fibers to attract small particles. However, these filters are not washable and must be replaced at least once per year. These filters are great for homes with children, pets and/or smokers. These filters are fairly expensive and have a MERV rating of 10 - 12.

High-Efficiency Pleated Filters

These filters screen out the smallest particles. They are made from deep 3" - 5" pleated synthetic cotton attached to a very stiff metal grid to stop leaks or fluttering, but can only be installed in a special housing due to their size. These filters are a good option for people with respiratory problems as they have a MERV rating of 14-16.
So, when choosing your furnace filter, keep in mind your needs as well as price and what the filter has to offer.