November 2, 2022
Furnace maintenance in Las Vegas, NV

How Long Do Furnace Filters Last?

You know you need to replace your furnace filter to keep your HVAC system working properly. But how often does it need replacing, and is it the same for everyone? Discover what’s commonly recommended, what variables influence filter life, the signs your filter needs replacing, and how to make sure you get the right one.

Inaccurate Rule of Thumb

Many variables influence how long your filter will last. However, if you talk to enough people or dig enough online, you’ll find what some people consider the golden rule of thumb for all filters. This may range anywhere from 90 days to as long as a year, depending on who you read, with the most common being about every 3 months.

Unfortunately, rules of thumb are rarely the right answer, especially when it comes to HVAC topics. While changing your filter according to a rule of thumb is better than never changing it, it may end up costing you. You can drive up your heating and cooling costs if it’s not frequent enough. Conversely, you may end up spending more on filters than needed, especially if your system uses a wide filter and you change it too often. Let’s explore the variables that affect how long your filter will last, and how to determine when is the right time to replace it.

Filter Width Matters Too

The first thing to consider is the size of the filter, which determines the amount of filtering material it uses. There are three dimensions you must consider for your filter, including its height, width, and depth. It’s the depth that has the strongest influence on your filter’s life.

Generally speaking, 1 and 2-inch filters have an expected life of up to 90 days. 4-inch filters may last up to 6 months and 5-inch filters may last up to a year.

Keep in mind these estimates are at the top end of the service life. However, multiple variables may cut that service life as short as a month.

Consider Filter Construction

The construction of your filter is another key factor in determining its service life. The basic filters are flat fiberglass and have the shortest service life. Keep in mind, they are also the least efficient filtering materials, so more contaminants will slip through the filter and settle in your HVAC system.

Better filters are made of paper, cotton, or polyester and are pleated rather than flat. You’ve likely seen these filters, they have what look like peaks and valleys in the filtering material. The benefit of this particular design is that it significantly increases the filtering area, which improves filtering efficiency and extends service life.

Be careful that you stay within the efficiency rating your system is designed to use. If it’s too efficient, like a HEPA filter, it may restrict airflow through the system, costing more to run heating and cooling cycles.

How’s Your Indoor Air Quality?

Outside of your filter’s size and construction, air quality is the most influential variable for how long your furnace filter will last. When we think about air quality, this includes all the things floating around in the air that may clog up the filter.

One of the biggest things affecting your air quality is your cleaning routine, especially vacuuming and dusting. If you aren’t doing these two important chores, then your air picks up some of the dust and dirt particles as it circulates throughout your home, putting them back in the air. Additionally, if you have pets or smoke inside your home, those significantly impact your home’s air quality.

Best Filter Habits

Whether you realize it or not, you have some habits with your air filter that go beyond how often you change it. These specific habits, or lack thereof, can extend or cut how long your filter lasts.

First, how often do you check your filter? If you’re not looking at your filter more than when you’re experiencing signs of a clogged filter, you’re cutting its life. One of the better things you can do is check your filter every month, regardless of its size.

Next, when you’re checking your filter, gently vacuum the intake side, which is the side at the back end of the arrow. This removes the particles on the outer part of the filter, extending its life and giving an airflow boost between filter changes.

Signs You Need a New Filter

Aside from checking your filter every month, keep in mind the signs that may indicate you have a clogged filter. If you have any of these symptoms, check your air filter before scheduling an HVAC service call.

The first kind of symptom to watch for is physiological symptoms people in your home may experience. This could include increased allergies or asthma responses, headaches, fatigue, and increased sinus or upper respiratory infections.

Next, watch for HVAC performance issues. These include low or no airflow, uneven heating, increased dust around your home, a burning smell, and even a lack of heat.

Finally, watch cost increases when you’re running your system. The first place you’ll notice this is an increase in energy consumption, which could be both fuel and electricity. In addition to using more energy, clogged filters left long enough may cause additional repairs.

What Happens if You Neglect Your Filter?

Your HVAC system depends on sufficient airflow, regardless of whether you’re running heat or air conditioning. Letting your air filter clog can significantly increase operating costs by causing longer heating and cooling cycles.

Additionally, clogged air filters can lead to extreme temperatures within the system itself. These extreme temperatures trip safety sensors, causing the system to shut down prematurely. Once the unit returns to a normal temperature, it will attempt to start back up, only to quickly shut down again. This process is known as short cycling, and significantly increases energy consumption and wear on your system.

Additionally, extreme temperatures can damage your furnace and air conditioner. If the system overheats, it can cause significant damage to your heat exchanger. This becomes an emergency repair, being it can quickly lead to carbon monoxide poisoning. It can also cause damage to electrical components and the evaporator coil needed for your air conditioning.

Making Sure You Get the Right Filter

As much as keeping a clean filter in place is important, so is replacing it with the right-sized filter. You can always check the size filter that you’re taking out to see what you currently have in place. However, you may want to double-check that what you’ve been using is the right size.

If your filter seems especially loose or tight, you may want to check the measurements needed. The easiest way is to take internal measurements of the air filter intake. Be sure you measure all three dimensions, then compare that to the filter you took out.

Getting the right size filter is important to ensure air is flowing through the filter rather than around it. Double-check what MERV rating your system can handle so that you don’t get a filter your system isn’t strong enough to draw air through.

Polar Air & Heating, Inc. has been the go-to HVAC service provider for people around Las Vegas since 1998. Our award-winning team provides AC and heating installation, maintenance, and repair together with indoor air quality solutions. Call to schedule your furnace repair or maintenance appointment with one of our NATE-certified technicians today.

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