They’re so unglamorous that they’re often forgotten, but furnace filters can affect your quality of life. It’s likely many of us simply accept they deserve infrequent attention. Others may completely forget about them assuming that they continue to do their job.
Just as the air filter in your car keeps the intake air clean until grime clogs it and it needs replacing, your furnace filter brings air into your home that affects air quality and it also needs regular replacing. Clogged filters decrease furnace efficiency and increase the dirt and allergens circulating in your home. Clark Public Utilities energy counselors suggest customers check their furnace filters monthly, especially during heating season when the systems are in use more often, to make sure they’re still in good working order.
“How often homeowners must change their filters depends on the type they use,” said Jake Gross, customer comfort specialist for Washougal-based Dan’s Top Notch Heating and Cooling. “Not changing furnace filters often enough can contribute to health issues, especially for people sensitive to dust.”
Four classes
Gross says that although there are numerous choices available, disposable filters generally fall into four classes for removing airborne particles ranging from the most porous and least effective to the least porous and most effective. Manufacturers rate filters according to a standard called MERV (Minimum Efficiency Reporting Value) and higher-rated filters catch smaller particles.
You can buy inexpensive filters rated 10 MERV or less for less than $10 each. The least costly and least effective are one-inch thick mesh fiberglass filters. They also need replacement about every two to three months. Similar one-inch pleated filters use a paper-like synthetic fabric to catch dust particles. These are a step up from the fiberglass filters and are slightly better at filtering out smaller particles. However, you’ll pay a bit more than for the fiberglass and also need to replace them every two or three months.
Homeowners wanting more effective filtration and better air quality should look for filters with ratings at 10 MERV or above, Gross suggested. These are available in two types also — folded pleat with a synthetic paper-like fabric and carbon-coated mesh fabric. The pleated units run about 10 MERV and the carbon-coated 15-20. For all filters, custom-sized ones can cost nearly two or three times more.
Some furnaces require permanent filters. If you have a permanent furnace filter, it’s important always to follow the directions for its cleaning schedule.
While furnace filters have benefits, when not used properly or installed correctly, they can hinder the passage of air or let excessive dust and other allergens flow into your home. When installing a filter, note the direction of the arrows on the old filter and insert the new one facing the same way.
For a healthier home, furnace filters are effective for improving air quality by reducing the spread of allergens. “We often hear that our customers feel better after we’ve installed a system with high-efficiency filters,” said Gross.
For those sensitive to dust and contaminants in the air, or anyone suffering from asthma or respiratory problems, Gross suggests at least a 16 MERV. Four-inch filters are better, although more costly, and only need to be changed out twice a year. At a higher rating, they also filter out nearly microscopic particles, including bug parts, smoke and many bacteria.
“If a furnace uses four-inch filters, homeowners shouldn’t stack one-inch filters together, because it increases back pressure on the fan,” Gross warns. “Instead, they should buy a four-inch filter, because it’s designed with more surface area for capturing contaminants.”
Energy Adviser is written by Clark Public Utilities. Send questions to ecod@clarkpud.com or to Energy Adviser, c/o Clark Public Utilities, P.O. Box 8900, Vancouver, WA 98668.
