Man removing a dirty furnace filter from a home HVAC unit

Furnace Filter Replacement - How Often Should It Be Done?

The filter in your HVAC system serves a few particularly essential functions. First, it helps keep your system operating efficiently throughout the year. Second, it helps your HVAC system maintain good indoor air quality by removing airbourne debris and dust particles, so you can continue to breathe clean air.  

However, during the colder months, when your AC is off, you may not give as much thought to replacing your furnace filter as you should. But replacing your furnace filter during the colder months of the year is just as important to system efficiency and indoor air quality as it is when your AC is running. In this article we’ll review when and how often you should replace your furnace filter.  

What Type of Filter Do You Have? 

Generally speaking, furnace filters usually come in a regular design (square and thinner) or a boxed design (square or rectangle and thicker). Furnace filter sizes are measured by thickness, height, and length. Since the thickness, height and length dimensions vary by filter type and unit model, check the owner’s manual for the recommended filter size for your unit.  

How often you replace your furnace filter depends on whether your furnace uses a regular or boxed filter. Since a regular filter is thinner, the furnace filter replacement time is usually shorter, about every two months (because the filter fills quicker). A thicker, boxed filter only needs to be changed about once a season (but should be checked periodically throughout the winter).  

What Type of Filter Should You Use 

Whether your HVAC system is designed for a regular filter or box filter, there are different types of air filters that you can choose from:  

Fiberglass HVAC Filters: These filters trap about 80% of the air particles that are 50 microns or larger and 25% of air particles that are 3-10 microns in size.  

Pleated HVAC Filters: A pleated filter will trap most airborne pollen, pet dander, and dust mites – as small as 5 microns. This type of filter is one of the most popular in North America.  

Electrostatic HVAC Filters: These filters trap particles 1 to 3 microns in size and typically come in a washable version. This can help reduce the cost of filter replacement.  

HEPA Filters: A HEPA filter is highly effective at removing air particles, trapping 95% or more of mold, fine dust, asbestos, bacteria, and viruses – as small as .3 microns. It is important to note, however, that these filters are also the most restrictive when it comes to airflow. No matter which furnace filter you choose, establishing a furnace filter replacement and maintenance schedule will help ensure your HVAC system continues to work efficiently throughout the year.  

What about Washable Furnace Filters? 

If you have trouble remembering when and how often you should change your filter, then a washable filter may be the way to go. There are several pros, and some cons to using a washable furnace filter. A washable filter will provide long–term savings, convenience, and limited waste. However, it takes a little more time and effort to maintain and clean a washable filter. Although you don’t have to worry about a filter replacement - you will have to clean it occasionally. In addition, washable furnace filters are usually not as efficient and are more susceptible to attracting mold and mildew (if not washed and dried correctly). Because of this, some homeowners prefer to forgo the washable option. 

Avoid Damaging Your System 

When it's time to replace your furnace filter, it is important to understand what filter your HVAC system is designed to use. Installing the wrong type of filter for your system could cause performance issues with your furnace. Your furnace may have to work harder to generate the same airflow. Plus, particles, dust and dander could build up, causing the furnace to be less efficient. This overload on your system can damage that results in hefty repairs (or the need for a replacement). A system that is not operating efficiently will also impact your energy bill too! Remember, you should never install a specialty filter without speaking with a heating and cooling professional first. Installing a specialty filter incorrectly could damage your system. 

Get Professional Furnace Filter Advice. 

One of the easiest ways to ensure your HVAC system is operating efficiently and maintaining good indoor air quality this season is to replace your furnace filter when needed. This will also help your system run smoothly and keep energy costs down.  

Although changing your furnace filter isn’t difficult you may not always remember to do it or have the time. This doesn’t mean you or your HVAC system has to suffer. The experts at Aire Serv can help. We can provide a wide range of services, including installation and maintenance, that will keep your system operating efficiently all year long. Schedule an appointment online or give us a call at (815) 552-2886 to get started.