9 Investigates

Should you buy that more expensive air filter?

CHARLOTTE — It's time to replace that dirty air conditioning filter and you go to the store. So many choices! Should you get the cheapest or go for the deluxe model that can cost four times as much? We wanted to find out, so we went to the experts at Central Piedmont Community College who teach students all they need to know about air conditioning.

HVAC instructors Roger McDow and Roger Spittle told us if the furnace is the beating heart of your home, the air filters are like the lungs. They clean the air circulated through your home - protecting you and your system from dust and debris.

The filter could be in a large intake vent on your wall or ceiling or right on the furnace blower itself. Finding them is especially a problem with renters who might not even know they exist.

McDow and Spittle say keeping an eye on them and replacing them regularly is important because old, overly-dirty filters restrict air flow and make your furnace work harder and longer. That could lead to costly utility bills and furnace repairs.

McDow says if the "filter is dirty, the compressor will have to work harder. So, it will pull more current and you will pay for it on your utility bill".

Filters typically have what's called a MERV rating from 1 to 20. The higher the number, the more small particles and debris are captured. Depending on the size and rating, we found prices from a few bucks up to 40 dollars. But Spittle says don't overspend. He recommends a middle-of-the-road MERV 8 which could cost less than 10.

"A good choice. You get much more than this you're gonna start to have a lot of restriction and your gonna drop a lot of pressure," Spittle said.

People with compromised respiratory systems, or the elderly who spend all day indoors, may want more filtration. You can buy UV lights that kill viruses and bacteria, or electrostatic units. But they can cost hundreds. So, your best, cheapest bet is a MERV 8 filter changed at the proper interval. About every 3 months, or monthly if you have pets.

If you've changed all your air filters and the air still seems musty or dusty, you could have a crack or break in your air return duct. It could be sucking air from the attic or even a damp crawl space back into your home. You can tape those up yourself or have a professional do it.

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