Do You Need to Replace Your Furnace Filter?

HVAC Dirty Air Filter

During the winter, your air heating and cooling system relies on a very simple component to keep it in top condition: your furnace filter. Air filters are designed to trap and remove fine particulates from the air that circulates through your system. From dust and dander to pollen and pet hair, furnace filters work hard while your HVAC system runs to protect equipment and improve indoor air quality.

Wintertime is especially hard on air filters, since your system will be recirculating indoor air day and night. You may need to check and change your furnace filter more frequently during the winter months to keep your furnace functioning as efficiently as possible. Thomas & Galbraith Heating, Cooling & Plumbing shares how to check and change your furnace filter to keep your air clean and your home comfortable.

Why Replace Your Air Filter?

Furnaces and heat pumps use different types of furnace filters. Air filters can either be disposable or reusable, depending on the needs of your system and your personal preferences. Many ductless HVAC units rely on washable, reusable metal filters, and conventional, forced-air systems typically rely on disposable filters. Homeowners may purchase reusable filters for HVAC systems, but these filters should be checked regularly and cleaned or replaced when they become damaged or dirty.

Unfortunately, many homeowners aren’t sure why filters are necessary. While it is true that air filters trap and remove particulates from your indoor air, their primary role is protecting your furnace. Air handlers and furnaces have delicate components and sensors, and even a fine collection of dust and grime could render your system less efficient. If ignitors, sensors, or moving parts become dirty, your system may run longer than it should, overheat, or function less efficiently, which can increase energy costs.

Every filter is rated with a MERV, or minimum efficiency reporting value. This rating measures the filter’s ability to remove particulates, with higher MERV ratings indicating the ability to trap finer particulates at greater efficiencies. A filter’s MERV rating ranges from 1 to 16, though MERV 13 is typically the highest rating appropriate for use with residential HVAC systems since using too powerful of a filter could block airflow and strain your system. Using the appropriate air filter gives you the chance to enjoy optimal air quality without consuming excess energy.

What Can Happen When You Don’t Change a Furnace Filter?

While using too powerful of an air filter can limit airflow, leaving a dirty filter in place can have a similar effect. Here are a few problems that occur if you don’t replace your furnace filter.

  • Dirty indoor air. When air filters aren’t replaced, dust and dirt can blow back into the system, filling your home with high concentrations of airborne pollutants. Residents may struggle with aggravated allergies or trouble sleeping due to sneezing or coughing. Dirtier air can also mean a messier home, since dust can settle on solid surfaces, carpeting, or ceiling fan blades.
  • Higher energy bills. As air filters trap dirt and become dirty, they can allow grime to enter back into the system, where dust and dirt settle on components. Dirty ignition systems, air handlers, and heat exchangers work less efficiently and require more energy than if they were clean, increasing energy usage and utility costs. Anytime your energy bills increase without clear cause, check to see if you need to replace your furnace filters.
  • Uneven heating. If your home seems to heat unevenly and you have cold spots throughout, your HVAC system may have airflow problems due to a dirty furnace filter. Old, dirty filters can cause resistance in your system, creating cold spots, especially in areas far away from your furnace.
  • Increased risk of breakdown. Furnaces that continue to operate when filters are dirty are at a higher risk of premature breakdown, since dust and grime can coat delicate sensors and moving parts, and force certain elements inside the furnace to overheat. Heat exchangers are especially prone to damage and can crack due to high temperatures. If the heat exchanger cracks, it can allow dangerous carbon monoxide gas into your home.
  • Decreased system life. When furnaces become dirty and strained due to grimy air filters, this problem can take years off of their expected lifespan. Furnaces will need to be replaced sooner than you might expect, especially if you don’t schedule routine annual tune ups designed to counteract wear and tear.

When You Should Replace Furnace Filters

You may wonder how you will know it’s time to change your filter. The timeframe for changing air filters may vary significantly due to the type, thickness, and rating of the filter, as well as the size and condition of your household. Homes with multiple pets, many occupants, and residents who love to cook indoors may require more frequent air filter changes, while vacation homes or single-occupant households may be able to go a little longer between air filter replacements.

Filters typically include information on the packaging regarding how often they should be replaced, and timeframes typically vary from every month to every few months. Some high-efficiency filters need less frequent replacement. Here are a few guidelines for how frequently filters should be changed.

  • MERV 1-4 Filters: Once a month.
  • MERV 5-8 Filters: Every 3 months.
  • MERV 9-11 Filters: Every 6 months.
  • MERV 12-16 Filters: Every 9 months to 1 year.

Keep in mind that all filters, regardless of MERV rating, may need to be replaced more often during the winter months due to increased system usage. Check your air filters every few weeks to look for dirt and grime buildup. Vacuum off or clean reusable filters according to manufacturer’s directions or replace disposable air filters as soon as they look dirty.

How Should You Install a Furnace Filter?

Replacing furnace filters is very simple, as long as you follow a few guidelines. First and foremost, it is essential to purchase the same size of filter as the existing one in your system. Before you visit your hardware store to pick up a replacement, open the access door on your air handler or furnace to see your existing filter. Check the markings on the existing filter to see if measurements, MERV rating, and brand information is available. It’s a good idea to take a photo of the filter for easy reference at the store. After you find and purchase the appropriate air filter, replace it using these steps:

  1. Furnace filters are typically located on the return side of the air handler. Access the old air filter by opening the access door.
  2. Pull out the old air filter. If the air filter is wedged into the unit tightly, you can bend the cardboard sides to pop it out of place. Keep in mind that disposable air filters are not recyclable, although some brands may offer a mail-in option for disposal.
  3. The new filter may have paper or plastic packaging around the unit. Remove all packaging and place the filter into the compartment in the exact same orientation the old filter was placed. Refer to your earlier picture for reference. Make sure that the arrow on the sides of the filter is moving in the same direction air would be traveling through the filter. If the filter is placed in backwards, it could impede airflow.
  4. If the dirty filter is washable, start removing dust and debris by carefully vacuuming the entire filter. Next, rinse the filter with clean water. Soap or other detergents should never be used, since these cleaners can leave behind a residue that attracts grime in the future. Place the washed filter on a clean, dry towel, and let it dry completely before reinserting it.
  5. Close the filter compartment door and secure the latches that hold the door in place.

Make Maintaining Your Furnace A Priority This Season

Replacing your furnace filter is a fast, easy way to protect your heating system all winter long. Remember, anytime you have questions about protecting indoor air quality, feel free to reach out to the team at Thomas & Galbraith Heating, Cooling & Plumbing for help. In addition to helping you to find the appropriate filter for your system, our professionals can also replace yours during routine system maintenance. Give us a call today to get started on the path towards a healthier HVAC system.

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