Most homeowners understand what air filters are and what their purpose is for indoor air quality, but when it comes to deciding which air filter you and your home needs, the options can be dizzying. Which is the best quality? Does price mater? What size do you need? Air filters don’t need to be as mystifying as rocket science, so we’ve laid out some important details to simplify the air filter decision process.

How do I know if I need a new air filter?
There’s a simple test that you can do right outside your home to determine how efficient your current filter is and see if you need to buy a new one or not. You can either complete this test outdoors or with something below your filter so you won’t have a mess afterward: Hold the filter horizontally and pour standard table salt through the filter. If some or all the salt falls through the filter, then you can bet that the filter will let salt-sized dust through, as well. The more salt that falls through your filter, the sooner you should upgrade your filter to something more efficient.

How do I choose a filter with the best material and rating for my HVAC system?
All air filters are rated in efficiency based on the MERV rating, which stands for Minimum Efficiency Reporting Value. MERV ratings range from 1–16 and the number rating tells homeowners how well the filter is designed to trap dust and dirt under the least efficient conditions. Here are some of the typical materials of air filters, their MERV ratings and how they correspond to efficiencies (these are only a guide and any further questions can be answered by our Climate Zone professionals to help you determine the best air filter for your home):

Fiberglass, Disposable Panel, Washable Metal/Synthetic, Self-Charging (Passive)
MERV 1–4: 60–80% average filtration efficiency

Pleated, Media Panel, Cube
MERV 5–8: 80–95% average filtration efficiency

Extended Pleated
MERV 9–12: >95% average filtration efficiency

Electronic
MERV 13–16: >98% average filtration efficiency

While a higher MERV rating may seem like it provides the best filtration efficiency, it’s important to be careful with high MERV ratings. The higher the MERV ratings, the more expensive it usually is to operate your HVAC system and the harder your system will have to work because there is not as much air that can flow through. Think about it this way; the most efficient “filter” would actually be a piece of plywood that would just trap ALL contaminants (and all the air) from entering your home. That’s maximum air filtration, but would also be the least comfortable way to go.

We usually recommend a MERV 6–8, but there may be reasons this isn’t the best type of filter for your home. For instance, if a member of your family suffers from allergies or respiratory problems, you may want to consider a higher MERV rated air filter or a whole-home air filtration system. Our Climate Zone experts in Haverhill are happy to talk through this filtration efficiency business with you to make sure that your home is comfortable, energy efficient, clean and not costing you a fortune to heat and cool.

What filter size should I get?
We’ve saved the easiest for last—the best way to determine which size filter you need is to simply look at the label of your existing filter or measure it you can’t find the labeled size. The standard home air filter is 1” thick.

Air filters are supposed to protect our homes and loved ones from harmful pollutants, dust and dirt, so it’s important that we understand all the facts about getting the best air filter for our personal needs. We hope this information has simplified the air filter phenomenon. But, if you have any further questions, feel free to contact the professionals at Andrew DiPietro’s Climate Zone in Haverhill at (978) 872-1190.