How to choose a furnace filter
Wondering why furnace filter prices have such a wide range? Will you get the product which worth money you spent? The answer is that you're getting a filter that requires less changing and captures more, and smaller, particles. The cheap woven fiberglass filters do one thing—screen out dirt and debris that could damage your furnace blower motor, though they do devastate some pollen and mold spores. In case you swap them out every month and air quality isn't an issue, these will do the job.
But if you're the kind of person who forgets to change the oil in your car, buy a low-priced pleated filter. It requires changing only every three months. If you stretched out the accordion-like material in these filters, you'd find two, three or four times the amount of surface area. This means they can catch smaller particles for longer periods of time without obstructing the airflow of your furnace.
If you smoke or have allergies or asthma, or if you have pets, look into the more expensive, high-efficiency electrostatic filters—ones that both filter and magnetically pull contaminants. Some are effective for up to a year. They can filter out bacteria, dander, odors and smoke particles. However health experts warn that you may be wasting your money on these filters if you don’t take the following steps:
- Use them in conjunction with a high-efficiency vacuum cleaner
- install a dedicated air purifier
- wash or vacuum the filter monthly
- take other steps to clean up your air and house as well
Don’t forget that filters work harder in summer! So changing filters isn't only a heating season chore. Many blower motors work at a higher speed in air conditioning mode than in heating mode, meaning you should change filters frequently in the summer. A clogged filter can make both your furnace and your air conditioner work harder and less effortlessly.
Pay attention to the Efficiency Rating
Many filters carry a MERV (minimum efficiency reporting value) rating, which indicates their effectiveness. The higher the MERV rating, the more effective. Most spun filters have a MERV rating of 4. Standard pleated filters average MERV 6. Electrostatic pleated versions start at MERV 8, with the highest quality ones hitting MERV 12.