Why your home's air conditioning filter matters more than you think

Every few months, most people complete a checklist of home maintenance projects, from changing the oil to prolong the life of cars, to clearing out gutters to prevent water damage and leaks, to putting fresh batteries in smoke alarms and carbon monoxide detectors.

But many checklists may be missing one of the most important maintenance tasks — one that keeps your home safer and your bills lower.

As long as your air conditioning unit is keeping your home cool, you may think it's in perfect working condition. If you're not replacing your AC filter regularly, however, it could lead to significant issues down the road, including aggravating seasonal allergies and increasing the cost of your electricity bill.

"Replacing air filters is one of the easiest things that a homeowner can do to prolong the life of their air conditioning system, increase the quality of air that they're breathing and decrease their utility usage as well," said Nick Scarnecchia, president of 6 & Fix, Inc., an HVAC repair and installation company in Raleigh. "A dirty air filter is not only going to ineffectively filter the air passing through, which is going to increase allergies and dirt in the house, but it also increases the cost of operating your air conditioning system. If you're reducing the air flow going in, then you're reducing the air flow going out, which means the system has to run longer in order to work properly."

In addition to running up costs on your energy bill, a dirty filter also forces your AC system to work harder, meaning a shorter lifespan and the higher possibility of costly repairs. Not only that, but by decreasing the quality of air in your home and introducing more dirt and allergens, it can also worsen allergies and respiratory issues.

In one particular case, Scarnecchia recalls a 6 & Fix customer who's summertime allergies were so severe, she was visiting the doctor on a monthly basis. After upgrading her air filters to a higher-end option, she was able to reduce her medical visits by 75 percent.

"She had been using poor ductwork and had poor air filtration for a while. The ductwork was leaking and some air was getting sucked in from the crawl space. Because the air wasn't being filtered correctly and the filter wasn't properly protecting the system, she had a lot of dirt built up through the ductwork," Scarnecchia said. "When you have dirt building up, it starts to grow microorganisms that pass allergens and those types of things throughout the house. We were able to clean her ductwork, seal it up and then install better filtration with better filters. Now, she's been able to reduce the frequency of visits to the doctor's office for allergies and chronic illnesses."

For those looking to replace their AC filters, Scarnecchia recommends at least a pleated MERV 8 air filter, an effective, all-around usage air filter that will not cause harm to most air conditioning systems and can serve as a starting baseline of air filtration for removing dirt and pollens in the air.

MERV refers to the thickness value of the filter and how many passing particulates it can catch as they move through. The higher the MERV number, the thicker the filter, and the thicker the filter, the more it catches. Filters range all the way up to MERV 13, but thicker filters don't typically work with older duct systems.

Aside from these warning signs, air filters typically last for one to three months, depending on usage. But the lifespan varies for every household.

"The thicker the air filter, the more frequently you need to change it. One of the most common myths of filters is a lifespan of a filter. Many might be advertised as 90-day filters, or something along those lines, but the thing about it is the filter does not deteriorate. A filter is only good until it's dirty," Scarnecchia said. "Different usage or a higher frequency volume of usage could cause the filter to get dirtier more quickly — like if you have kids and dogs and you're constantly going in and out of the house as opposed to one or two people at home at a time and no pets."

As a general rule, Scarnecchia recommends that filters are checked once a month and replaced at least every two months. Most air filters can be cleaned monthly by vacuuming off dust then rinsing under water, making sure to completely dry the filter before putting it back in place.

Especially now, as summertime rolls around and allergy season hits a peak, it's crucial to make sure the air in your home is as clean as possible. Checking on the status of your AC filter can help keep your home safe.