Here's How Often You Need to Change Furnace Filters During Winter

The Short Answer Is: Homeowners should change the furnace filter every one to three months during the winter, depending on factors like filter type and household conditions. Regular filter changes are crucial because a dirty or clogged filter can restrict airflow, reduce heating efficiency, and even lead to system breakdowns. Choosing the right filter for your system is important to ensure proper filtration without causing undue strain on the furnace, as using the wrong filter can impact indoor air quality and overall system performance.

Your furnace performs several critical roles within your home, including warming and filtering your supply of indoor air. As your air heating and cooling system runs throughout the year, your system moves airflow through furnace filters, which are designed to trap fine particulates. These filters remove dust and dirt that could accumulate inside your furnace and clean pet dander, pollen, dust, and other matter from your home to improve air quality.

Replacing your furnace filter regularly is a good idea because it keeps your HVAC system and your indoor air safe and healthy. During the winter, you may need to change your furnace filter more frequently since many families spend more time at home and the system is used heavily. Use this guide to help you to find out what you need to replace your filter and how often to take care of this important maintenance task.

Why Should You Switch out Your Furnace Filter?

Changing out your furnace filter is an essential component of HVAC maintenance that your heating and cooling system requires multiple times per year. Depending on your system, you may have a disposable or reusable furnace filter. Reusable furnace filters are common in ductless HVAC systems and may consist of a thin, metal, perforated sheet that you remove, rinse off, dry, and replace. Most conventional forced air heat pump and furnace systems use disposable filters.

Regardless of which filters your system relies on, it is important for homeowners to understand why filters are important and how they work to remove dust, dirt, and fine particulates from your indoor air.

While your furnace, heat pump, or air conditioner may seem very sturdy, your system relies on delicate internal sensors and components that may not function appropriately when they become dirty or damaged. For this reason, air filter replacement improves efficiency and system performance, lowering your winter energy costs and extending the life of your heater.

The role of an HVAC filter is to remove particulates as airflow moves through the unit. While the main role of air filters is to protect the delicate internal workings of your furnace, homeowners also enjoy better indoor air quality as a result of excellent air filtration. Every filter has a MERV rating, or Minimum Efficiency Reporting Value, which measures a filter’s ability to screen particulates. Higher MERV ratings indicate a finer filter capable of trapping more dust and debris, while lower ratings indicate more porous filters that don’t screen as many.

However, when any air filter becomes dirty, its ability to promote adequate airflow throughout your furnace becomes hampered. Replacing your air filter promotes proper air filtration while also balancing pressures within your system and reducing static buildup.

What Can Happen if You Don’t Replace Filters?

Oftentimes, homeowners get busy and forget to replace air filters. While this may not seem like a critical issue, it can cause big problems for your heating and cooling system. Always keep extra furnace filters on hand and be ready to switch them out as soon as they appear dirty. Here are a few issues caused by failure to replace air filters:

  • Increased energy use. When air filters become clogged and dirty, air that passes through the system can push grime further into the furnace, where dirt and dust can accumulate onto components within the furnace. When furnace components are dirty, they aren’t as capable of transmitting heat, forcing the furnace to run longer to generate the warmth your home needs. As a result, energy bills may increase.

  • Spotty heating. Dirty filters can block airflow significantly enough to prevent warmed air from moving into the rooms of your home. Dust and grime can even coat the insides of ducts, creating full blockages. Either problem can cause cold spots throughout your home since air pressure may not flow evenly throughout your home. Locations furthest away from your furnace are the most likely to be cold and uncomfortable if air filters or ducts become dirty since the air will have to travel farther. When airflow is restricted, the heating system uses more energy in its attempts to move warm air into your living areas.

  • Higher risks of emergency breakdowns. When dirt accumulates within your furnace, it can stress critical components. As a system with a dirty air filter and blocked airflow attempts to heat your home, it may overheat, shut down the system, or even crack the heat exchanger and damage other delicate components. Each of these issues is serious, and emergency professional HVAC repair may be necessary to restore heat.

  • Shortened furnace lifespan. If you want to get the most life possible out of your furnace, replacing the air filter is critical. Operating HVAC systems with dirty filters can cause problems that need repairs or even shorten the life of your furnace. However, routine filter replacements and professional tune-ups help counteract wear and tear so your system lasts as long as possible.

  • Reduced air quality. Dirty air filters lose their ability to filter contaminants, allowing particulates to cycle back throughout your home. Many homeowners notice higher levels of dust or more problems with allergies when air filters aren’t replaced appropriately.

When to Replace Your Furnace Filters

There are many factors that play into how often your air filter will need to be replaced, including filter variety, thickness, size, MERV rating, and even the number of people in your household. If you have indoor pets or family members with allergies, you may need more frequent air filter changes. Smokers or homeowners who are undergoing home renovations may also need to switch out their air filter more often.

Filter manufacturers offer basic recommendations for the lifespans of different varieties of furnace filters. Keep in mind that depending on which type of filter you use, you may need to replace your filter as often as every few weeks or as infrequently as every six months to a year. Become familiar with your furnace filters to learn what the manufacturer recommends, but keep this guide on hand as a general rule of thumb.

  • Merv 1–4 Filters: Replace Once a Month
  • Merv 5–8 Filters: Replace Every Three Months
  • Merv 9–11 Filters: Replace Every Six Months
  • Merv 12–16 Filters: Replace Every Nine Months to One Year

Wintertime is especially hard on furnaces and their filters since most people run heating more often. Higher levels of system usage can fill up filters faster, so check your filter every few weeks and switch it out as soon as it becomes dirty.

How Should You Replace Your Furnace Filter?

Switching out your furnace filter is fast, easy, and a job that any homeowner can tackle on their own. Changing filters is as simple as accessing the old filter and replacing it with a new variety, but there are a few critical things to know to take care of the job correctly.

It’s important to replace your old filter with one that is the exact same size, so write down the size indicated on your existing filter and bring that information with you to the hardware store when you pick up a replacement. Before you choose a filter, check the markings on your old filter and the instructions within your furnace’s owner’s manual to ensure you have the right model for your system. Many residential systems won’t operate appropriately if a filter with an exceptionally high MERV rating is used since these can block airflow – MERV 13 is typically the highest rating appropriate for residential heaters. The replacement filter should fit perfectly within the cabinet and allow air to pass through easily.

Step-by-Step Instructions to Replace an Air Filter

  1. Find the air filter compartment on your furnace. Most systems have this compartment on their return side, where air enters the unit for heating. There may be a compartment door to open that conceals the filter.
  2. Take a picture of the placement of the existing air filter for future reference. Remove the filter and dispose of it. If your filter is reusable, clean it according to manufacturer’s instructions. Most reusable filters require vacuuming and then rinsing to loosen and remove debris. Never use soap, as this can leave behind a residue that attracts new dirt. Let the filter dry before reinserting. Some manufacturers offer a mail-in recycling option for disposable filters, so look for mailing instructions if that is the case.
  3. Remove plastic coverings from the new filter, and pop it into the filter compartment. Make sure the arrows on the sides of the unit move in the same direction airflow travels as it moves through the system. Refer to your previous photo to ensure the new filter is in the same orientation as the old model.
  4. Close the filter access panel.

Maintain Your Furnace This Winter

Filter replacement is important for the health of your furnace, so take the task seriously. Keep extra filters on hand so you can always switch yours out if you need to, and set a reminder in your phone or on a personal calendar to check your system every few weeks or at least once a month. Remember, you can always contact us here at Jarboe’s Heating, Cooling & Plumbing if you have the need for Louisville furnace repair help or annual furnace tune up service, or questions about your system. We are always here to help!

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