The forced-air furnace or central air conditioner in your home plays a double role: not only does it keep your home at a comfortable temperature but, because it’s responsible for circulating air, its air filter is your first line of defense against airborne particulates. Air filters should be replaced every month or two for best performance, meaning that you’ll have a lot of opportunities to test out your options, but here are a few things to consider when you’re buying a new air filter.
Air filters work by passing air through a fine, fibrous mesh. This mesh, like a sieve, strains out particles such as dust, dander, mold spores and bacteria, allowing the now-filtered air to pass through.
Filters also vary in efficiency. They’re rated according to the Minimum Efficiency Reporting Values (MERV) system, a numeric rating of one to 16, with higher numbers representing more efficiency. High Efficiency Particulate Air (HEPA) filters can be thought of as filling in the MERV ratings from 17-20. An air filter with a MERV value of one will catch dust mites and pet fur, but it won’t impede the flow of things like bacteria. A MERV of 16 means that most of the bacteria circulating through will be filtered out, as well as anything smaller.
So does this mean you should go for the highest-efficiency filter available? Not necessarily. Home furnaces are rated to handle certain efficiencies, because the finer the mesh (and the higher the MERV), the more difficult it is to pass air through the filter. Installing air filters that provide too much obstruction can cause undue strain on your HVAC system’s blower fan, and even lead to system failure. The same can happen if a system is allowed to become clogged.
Central and standalone air cleaners are available, some with HEPA filtration, but not all homes require this standard of air care. Homes with the very young, elderly or immunocompromised residents may consider purchasing a HEPA air cleaner for health.
Our goal is to help educate our customers in Corpus Christi, Texas about energy and home comfort issues (specific to HVAC systems). For more information about air filters and other HVAC topics, download our free Home Comfort Resource guide.
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