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How Often Do My Furnace Filters Need Changing?

Despite nearly everyone knowing about furnace filters, they remain one of the most neglected furnace maintenance tasks. One of the problems is simply remembering how often they need changing, and the last time you did it. To help solve the conundrum, here is some information on how frequently you should change your furnace filter.

The Short Answer

The overly simplified, really short answer is every 90 days. However, the full answer is a little more complex as there are several factors that affect this frequency. The first factor is your furnace filter’s thickness. The 90-day recommendation is for 1- and 2-inch filters. If you have a thicker model, the filter life extends.

For 3- and 4-inch filters, plan for a replacement about every six to nine months. If you have the larger 5- or 6-inch filters, they will need replacing every nine to 12 months.

Why Changing Your Filter is Important

You may be questioning why it’s so important to change your filter, and why this gets so much attention in the HVAC industry. To understand this, you have to understand the basics of how your system works.

To heat your home, your system must be able to draw air in and then push it back out. Without this air circulating, your system will produce heat, but it’ll stay contained in the furnace and never heat your home.

Your filter is at the beginning of the process, filtering contaminants out of the air before they enter the furnace. This protects the internal components from collecting a large number of contaminants, which can damage the system and reduce its service life.

Considering Your Air Quality

Another critical consideration is your air quality, which is affected by how many contaminants are floating around in your air. The worse the air quality, the more quickly your air filters will clog and need changing.

Things that lower air quality are pets, improperly managed humidity, and the season. You may experience worse air quality in the winter when the air is naturally drier. While spring may have more contaminants outside, those particles have to make their way into your house. Winter, on the other hand, creates more contaminants inside if you don’t properly humidify your home.

That means that your filter is more likely to clog up sooner over the cooler months. Instead of assuming how often you need to change your filter, just check it monthly. This builds in a frequent routine, so it’s easier to remember. It also ensures that you replace your filter as soon as it’s dirty enough to cause an airflow restriction. While checking it, gently vacuum off the intake side of the filter to help extend its life and improve efficiency between changes.

Properly Sizing Your Furnace Filter

It’s important to get the right size filter to fit your furnace. There are three dimensions you need to fit properly.

First, you want to match the length and width of the filter. If the filter is too big, it simply won’t fit. If it’s too small, it’ll allow unfiltered air to flow past it.

Then there’s the filter’s thickness, which indicates the amount of filtering material. Despite what may seem like room to fit a thicker filter in your furnace, it’s important to use the manufacturer’s recommendation. Using a filter that’s thicker than recommended may restrict the amount of air flowing through your system, causing too much strain and reduced efficiency.

Signs You Have a Clogged Filter

If you forget to change your furnace filter, your system may give you some signs that it’s clogged and needs replacing. First, you may notice your system is not pushing out as much air as normal. You may also notice your home doesn’t feel as warm as it should for the temperature setting.

Additionally, your furnace may run longer cycles than normal, which should be about 10 to 15 minutes. This happens when your system can’t produce or circulate enough heat. You may also notice more dust around your home than normal.

People around Franklin rely on Dugan Air Heating Cooling for reliable heating and air conditioning service. Our team specializes in the installation, maintenance, and repair of a large range of heating and air conditioning systems. We also provide indoor air quality services. Call to schedule a maintenance or repair appointment with one of our NATE-certified technicians to keep your furnace running strong all winter.



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