How Often Should You Change Furnace Filters

Furnace installation is a significant expense for most homeowners, so it’s important to do whatever you can to protect your investment. Along with routine tune-ups from a professional technician, changing the filter regularly is one of the most important things you can do to achieve optimum performance and ensure your furnace stays in good condition.

If your home has a furnace and you haven’t been paying attention to the filter, it’s time to add this important task to your home maintenance routine!

As a heating and cooling company that’s been in business for more than 50 years, we have worked on countless furnaces. When we get a call about a furnace not working properly, one of the first things we ask the caller is how long it’s been since they changed the filter. Some homeowners admit they’ve never changed the filter and didn’t know they were supposed to.

After experiencing this so often for so many years, we thought it would be helpful to provide some information and tips about furnace filters for our customers and other homeowners.

How a Furnace Works

Your furnace is part of your home’s HVAC (heating, ventilation, and air conditioning) system. We won’t get too into the technical details, but if your home has a traditional forced-air system – the most common heating and cooling system – it draws air in, warms or cools it, and pushes the air through ducts that carry it to various rooms throughout your home.

As the warmed or cooled air makes its way throughout your home, a fan pulls existing air out through a separate set of ducts and toward the heat exchange, where it is again heated or cooled. This cycle continues until your home reaches the temperature you set on a thermostat.

The Purpose of Furnace Filters

The main purpose of a furnace filter is to protect the blower fan from dust, hair, and other contaminants the return duct pulls in. But the added bonus is that by catching these particles, the filter improves the quality of air inside your home.

Without furnace filters, the IAQ (indoor air quality) of your home would be poor, and all of the dust, dirt, crud and other contaminants would pile up in your furnace and ductwork. All air that passes through a filter is treated and recycled, so it is healthy to breathe. When dirt, grime, and crud start to pile up in a furnace, and especially air ducts, mold starts to form.

Simply put, the filter is responsible for removing contaminants from the air, as well as maintaining the cleanliness of your HVAC system’s ductwork.

Signs Your Furnace Filter Needs to Be Changed

As dirt and other particles accumulate on a furnace filter, air can't pass through. If neglected, your HVAC system can overheat. A full filter also cannot not prevent dirt and other contaminants from circulating through your home, which means your family will breathe more dust and allergens daily until the filter is replaced.

Here are a few signs it’s time to change your filter:

• Your home seems more dusty than normal.
• You notice a strange smell or a burning smell near your furnace or HVAC system.
• The filter is visibly dirty.
• Your HVAC system is running more frequently than usual.

How Often to Change Furnace Filters

Two main factors determine how often you should change air filters: MERV rating and filter size.

MERV (Minimum Efficiency Reporting Value) ratings refer to the ability of a filter to trap particles. MERV ratings range from 1-20, with 20 being the highest value.

While you may think that getting the highest level of filters is the best option, think again. Residential HVAC systems have limits and requirements, so unless you work in a hospital, don’t go above 15.

For residential filters, 13 is the magic number.

Your furnace filters may need to be replaced every month, but sometimes it is only necessary to replace them a couple of times a year. To judge how often you have to replace your furnace filter most of the time, look at the filter size, also known as thickness.

As a rule of thumb, replace:

• One- to two-inch filters every one to three months
• Three- to four-inch filters every six to nine months
• Five- to six-inch filters every nine to twelve months

Some Homes Should Change Filters More Frequently

When to change your furnace filter is not a hard and fast rule. You should consider changing your filters more often than the guidelines provided above if any of the following apply!

You Have Pets

If you have furry animals at home, your filters can get clogged with hair much faster. The more animals living with you, the shorter your filter’s lifespan will be.

Your Home Has Many Occupants

Pets aren’t the only ones that impact the speed you need to replace furnace filters. The more people you have in your household, the more particulates come through to your filters.

You Like Opening the Windows

When windows are left open, more dust and debris get into your home and circulate in the air.

You Have Allergies

If you or anyone in your household has allergies, changing the furnace filter more often can help relieve symptoms.

You Smoke Inside

The more smokers living in a home, the shorter your filter’s lifespan will be.

You Use Your Furnace A Lot

During the winter and cold seasons, you will have your furnace on for longer to heat up your home. When this happens, more air is being circulated through your home, which means more particulates are reaching your furnace.

Humidity Is an Issue

Despite Minnesota being stereotyped as a cold, snowy place, it is actually fairly humid year-round, especially in summer. Greater amounts of airborne particles come through humid air.

Additionally, humidity deteriorates the effectiveness of your filters and allows bacteria, mold, and pathogens to fester around your filters.

Contact MN Professionals for Furnace Tuneups & Repair

If you’re still not sure how often to replace the furnace filter in your home, just keep an eye on it. If it’s visibly dirty, it’s time for a replacement.

We recommend setting a reminder on your smartphone or calendar a month before you expect your filter to be replaced.

If you want your HVAC system to achieve optimal performance, it’s important to hire a professional technician for routine maintenance checks. For those located in the greater Twin Cities metro area, contact General Heating & Air Conditioning!

Our experienced technicians can investigate key components of your furnace that may need to be replaced and look for things like leaks and faulty heat exchangers or ventilation systems. By optimizing the performance of each component of your furnace, we can provide solutions to improve its energy efficiency and longevity.

You’ll also get the chance to ask any questions you may have about the rest of your HVAC system. Call us today at 952-445-2820 to schedule a service!