how often to change furnace filter

How Often to Change A Furnace Filter for Best Air Quality

Ian Mutuli
Updated on
Ian Mutuli

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.
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There is no right or wrong tie to change your furnace filter. However, as a general rule of thumb, you need to change your air filter at least once every three months or 90 days for pleated air filters. Furnace air filters should be changed as often as necessary.

How will you know that your HVAC system needs to change? What determines when the furnace filter needs a change? To get answers to your questions, please keep reading.

What Does a Furnace Filter Do?

Isn't it true that your furnace filter catches airborne particles and cleans your air? But, while it does that, it is not its primary function - contrary to popular belief.

A furnace filter's primary goal is to trap airborne particles, not improve air quality, but keep them out of your heating and cooling system. However, because the filter removes impurities for the benefit of the system, air quality benefits as well.

What Affects the Frequency of Changing Furnace Filters?

Your HVAC air filter may need replacement more often than mine and than someone else's. This frequency varies depending on different factors, which we shall discuss below.

a). The Rate at Which You Use Your HVAC System

A single filter can last you from a season to a year if you live in a moderate area and use your heater or air conditioner for a few hours every day. However, change your filter every few weeks if your HVAC system is operating on a near-constant basis (especially if you're using a cheaper fiberglass filter).

b). Outdoor and Indoor Air Quality

The air quality inside and outside your home impacts the frequency with which your filter needs to be replaced. For example, if you have pets or poor air quality, you will need to replace your air filter frequently.

c). Size of Your Home

In smaller homes, furnace filters and air conditioners must pump less air to achieve the exact temperature change, necessitating fewer filter changes. However, because these appliances often have smaller filters, they may need to be replaced equally frequently as filters in a bigger home.

How Often Should You Change Your Furnace Filter?

Changing dirty furnace filters is a duty that varies in regularity from house to house. The frequency with which this task must be completed is mainly determined by the type of furnace filter in use. If you look down the filter replacement aisle at your local hardware shop, you'll see that there are a lot of possibilities — a variety of filter types to effect altering frequency.

Changing furnace filters should be done once a month to once a year, depending on the type of filter. There is a vast range of how often filters should be updated, just as there is a wide range of types of filters. Fortunately, changing furnace filters isn't a guessing game. When you buy a new filter, the manufacturer includes product information that includes the recommended replacement frequency.

Size counts when it comes to determining how frequently you should change your furnace filters. Because thicker filters have more media to absorb pollutants, a 5-inch filter needs to be changed less frequently than a 1-inch filter. Filter efficiency has an impact and is expressed as MERV, an abbreviation for Minimum Efficiency Reporting Value.

In general, this is how frequently furnace filters should be changed:

  • Filters with a diameter of 1 to 2 inches should be replaced every 1 to 3 months.
  • Filters with a diameter of 3 to 4 inches need replacement every 6 to 9 months.
  • Filters with a diameter of 5 to 6 inches need replacement every 9 to 12 months.

What are the Effects of a Dirty Furnace Filter?

The air filter will eventually filter all of the air that passes through your HVAC system to heat or cool your home. This is why it's critical to keep your air filters clean and replace them regularly. Filters that are dirty or clogged can cause:

  • Cause problems in HVAC systems and equipment damage.
  • Reduce the airflow in the HVAC system, making the fans work harder and wear them out faster.
  • NOT removing particles and toxins as well as they should, resulting in their reintroduction into your interior air (or the air you and your family breathe).
  • Contaminants will build up in your ductwork as a result of this.
  • Increase your home's energy consumption and monthly power bill payments by making the HVAC equipment work harder.

At least once a month, the status of ac filters and furnace filters should be checked. If they're filthy, replace them with a new, clean air filter. If you hold the air filter up to a light source while removing it from the air handler, you'll be able to see if it's dusty or clogged; if you can't see the light through the filter, it's time to replace it.

How Will You Know When You Need to Change Your Furnace Filter?

The following are some of the signs that your air filter needs a replacement.

  • On your intake vents, dust and debris have accumulated.
  • Dust and debris accumulate around your output vents, frequently on the ceiling and adjacent walls
  • Dust is gathering on fan blades, curtain rods, and the tops of cupboards, signaling too much dust in the air.
  • Loss of cooling power in your air conditioner
  • When your air conditioner starts up, you'll hear a lot of strain.
  • For your AC system to cool to the proper temperature, you'll need to operate it for more extended periods.

Factors to Consider When Changing a Dirty Filter

A dirty filter will not effectively filter every particle present in the air. Therefore, you may need to change your furnace filter every few months. However, before you do so, you will need to consider a few factors that will help you know how often you need a filter change. Some of the things you should keep in mind to help you make this decision include the following.

a). Pets

If you own furry pets in your home, your furnace filter's life will be cut short. You should change your filter once every two months for a one or two-inch filter, four months for a four-inch filter, and six months for a five-inch filter if you have one animal at home.

The more animals you own, the sooner your air filter will need a replacement. If you have many animals, you should change one or two-inch filters once a month, four-inch filters once every two months, and a five-inch filter once every 90 days.

If your pet sheds a lot of furs, it's a good idea to take them outside regularly for a thorough brushing to limit the quantity of hair and dander that enters your home and lower indoor air quality.

b). Smokers

If you have smokers in your home, your filter will be affected as well. The more smokers within the house, the shorter your HVAC air filter life is, especially if they smoke indoors. You can get away with changing a one or two-inch filter every two months, a four-inch filter every four months, and a five-inch filter every six months if you just have one smoker in the house.

If you have numerous smokers in the house, reduce the frequency to once a month for one to two-inch filters, twice a month for four-inch filters, and three times a month for five-inch filters.

c). Frequent Open Doors and Windows

When you often leave your doors and windows open, dust and toxins from the outside air enter your home, adding to the filth on your air filters. One and two-inch filters should be updated monthly, four-inch filters every two months, and five-inch filters every three months if your windows and doors are frequently left open.

d). Allergies

If anyone within your home suffers from any allergies, changing the air filter more frequently will help. A higher-quality filter will be more expensive, but it will reduce allergens more effectively.

It's a good indicator of how often your furnace filters need to be replaced if you're aware of the factors that influence indoor air quality. Changing your furnace's filters regularly can help ensure that your furnace performs smoothly and efficiently and that the air you and your family breathe is as clean as possible.

e). Dust

Another factor that might affect the life of your furnace filter is excessive dust. If your home is dusty, you should replace one and two-inch filters once a month, four-inch filters every two months, and five-inch filters every three months.

f). Heater Fan

The frequency with which your heater fan runs will determine how frequently you should replace your filter. If your heater fan is on all the time, you'll need to change your filter every month; if it's on occasion, it'll be every two months; if it's never on, it'll be every three months.

Frequently Asked Questions (FAQs)

1. What happens if you don't change your furnace filter?

The furnace will overheat every time it starts up again if it doesn't have a new air filter. Short cycling is the term for this. Due to a reduction in airflow, dirty furnace filters make your furnace work harder than it should. The more you use your furnace, the faster its parts will wear down and need to be replaced.

2. Is no air filter better than a dirty one?

It's worse to run your air conditioner without a filter than it is to operate it with a dirty one. So instead, go to the store as soon as possible to acquire a replacement or contact an HVAC professional. Your air conditioner is at risk of severe and costly problems if you don't use a filter.

How often you change your furnace filter determines the air quality you breathe and the energy you consume, so consider changing them more often.

Ian Mutuli

About the author

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.
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