Do you remember the last time you thought about the furnace filter in your home? If it’s been a while, it’s probably time to consider replacing your air filter. After all, regular maintenance is essential for the longevity of your furnace.

And even more important is the health and safety of your family. Your furnace and air conditioner must work twice as hard to circulate air through your home when the air filter is full of dust, filth, and grime. Changing your furnace filter is a quick and easy method to keep your indoor air clean and save money on heating system maintenance.

This article will discuss the importance of your furnace filter, how to change a furnace filter, and how often to change a furnace filter.  So, let’s get started!

How to Change a Furnace Filter In a Nutshell

If you’re looking for the quick answer, here are the six steps to changing a furnace filter. We’ll go into more detail about the process later in this article.

  1. Determine your filter size.
  2. Find your filter slot.
  3. Turn off your HVAC system.
  4. Take out the old filter.
  5. Insert the new filter.
  6. Turn your HVAC system back on.

And there you have it! Now let’s get into the nitty-gritty of how to change a furnace filter.

The Importance of Furnace Filters

The furnace filter is one of the most crucial components of any HVAC system, with the most important parts being the heat exchanger and condenser coils. The filter’s job is to make sure harmful or irritating pollutants such as dust, pet hair, smog, and bacteria do not cycle through your home, and subsequently your lungs, every time your system turns on.

The filters are located within the HVAC unit itself and in the air return vents that are often strategically placed in a building’s walls and ceilings. These returns are how the air handler sucks in air to be recycled by the system. All heating and cooling systems should connect to at least one return to provide good air pressure and flow, but it is always beneficial to have more.

Why Should I Change my Filter Frequently?

More often than not, many people forget that they need to change furnace filters.  Clogged or overburdened filters can cause restricted and contaminated air to move through your system.

If the filters in your home become too dirty, they can cause damage to your system’s motor, resulting in hundreds to thousands of dollars in repair costs. Resulting high pressures can also cause damage to the metal and framing that support the ducts and vents.

These inefficiencies and mechanical failures can also make your system work harder or force it to run more prolonged heating and cooling cycles.  These Inefficiencies have other impacts as well, like an increase in your utility costs.  And quite honestly, no one wants to waste their hard-earned cash on something easily preventable.

Dirty Furnace Filter, How To Change A Furnace Filter

How Often Should I Change my Furnace Filter?

Typically, it is a good idea to check on the status of your filters at least once a month, especially if you are using a new brand or type of filter. Checking your filters at regular intervals will help you determine how often you should replace or clean them.

For example, if the filter has a layer of dust/debris, has trapped a lot of pet hair, or just looks gross in general, it may be a good time to replace it. Of course, how often you should replace your furnace filters is also based on the thickness and method of filtration.

Many factors affect the debris loads of furnace filters. As mentioned previously, if you have one or more pets in your home, pet hair and dander can quickly clog and prevent your filter from operating efficiently.

If you or someone in your family smokes this will also cause filter build up more quickly. The same goes for houses and buildings that are exposed to large volumes of wildfire smoke. It is also wise to observe the amount of dust that accumulates in your home.

If you notice that dust levels are higher than normal, or you find yourself breaking out the Swiffer more frequently, it may be time to change your filters.

If you leave your windows and doors open more often, more dust and debris will be looking to invade your private airspace. It’s always nice to invite the sweet Spring air in, or a refreshing summer breeze, but just be mindful of your furnace filters’ condition after a month or two.

It is also important to keep in mind how often your unit runs during its heating and cooling cycles. For example, if the fan runs for an extended period, the filter works just as hard to filter out the unwanted particles traveling through the air.

Which Filter is Right for me?

There are lots of different filters that you can buy on the market today. But, sometimes, it can be tough to determine which kind is the right fit for your specific needs.

The most common filter is the low efficiency, disposable fiberglass filter. While this is the most cost-effective solution, it is also the least protective, with MERV ratings of around 4 or lower.

In addition, fiberglass filters can feature a flat-panel design or a pleated design to maximize surface area. There are other disposable filters on the market made using various plastics and synthetic materials that are safer and more efficient, but this also means that they cost more.

Washable/reusable filters are becoming increasingly more common due to their low environmental and financial impact. These filters can be either electrostatically charged or filter out particles using mechanical filtration.

Electrostatic filters contain charged ions that attract and trap smaller particles such as viruses, bacteria, and smoke. In comparison, mechanical filters excel at trapping larger dust particles, pet hair, and other debris. Some filters, such as our Filti Washable Filter, harness the power of both to provide cleaner air for your home.

One of the most important factors to consider when searching for a new filter is the MERV rating. MERV stands for Minimum Efficiency Reporting Value. The MERV rating defines how efficient the filter is for a specific particle size. The higher the rating, the more efficient the media is.

Merv Rating Scale, How To Change A Furnace Filter

For more specific information and guidance on the different HVAC filters, check out one of our other articles: Washable Air Filters Vs. Disposable Filters – Which is Right for You?

How to Change a Furnace Filter

In this section, we will go over how to change a furnace filter. But, don’t worry, changing your furnace filter is quick and easy! Follow the steps down below to change out your old filter safely.

Step 1: Determine which filter size your system requires.

First when you learn how to change a furnace filter, pay close attention to the dimensions that it specifies, especially the depth of the filter, as HVAC systems are very particular. If you try to use a 1” filter in a 2” slot or larger, you will experience compilations and potentially damage your system.

Also, do not try to layer multiple 1” filters in larger slots, such as 4”, as they are not designed for this use unless specified by the manufacturer. Some systems allow for pre-filters or multilayered ones to be installed, so it’s always good to double-check!

Step 2: Locate the filter slot.

Most filter slots are located either in the ductwork leading into your unit or in the blower compartment (can be found by lifting up on the furnace cover). If you can’t find the filter slot, consult the operation manual. If you do not have an operation manual, call your friendly HVAC provider or technician for assistance.

Step 3: Turn off your HVAC system before you go to replace the filter.

If the system is running or happens to turn on in the middle of the exchange, it could blow loose debris or filter fitting further down the line. There should be a switch on your thermostat that allows you to manually turn the system off until the new filter has been installed.

Step 4: Remove the old filter.

This step is as easy as it sounds. Your filter should slide right out. Sometimes, the filter will be plugged into the unit if it is an electrostatic filter. If this is the case, unplug the filter first and then slide it out.

Step 5: Insert the new filter.

The next step in how to change a furnace filter is just like the last step but in reverse! Make sure nothing is obstructing the filter slot or in the way of the filter once you slide it in. It should be clean and void of debris. There should be an arrow, usually located on the side of the filter, that indicates airflow direction.

Make sure this arrow is pointing towards your unit. Air flows from the condensers outside your house, through your ducts, and into the air handler through suction. It is vital to make sure the filter faces the right way to keep it from collapsing or deforming over time.

Most filters have a support structure made out of metal, plastic, or cardboard in the back to prevent this.

Step 6: Turn your system back on.

Finally, in our guide on how to change a furnace filter, don’t forget to put the switch on the thermostat back to the “on” position after you have installed your new filter.

How To Change A Furnace Filter

Congratulations! You have now successfully renewed your home’s ability to provide you with fresh and clean air.

Wrapping up How to Change a Furnace Filter

We hope you found our article on the importance of furnace filters and how to change a furnace filter helpful!  Here at Filti, we are passionate about helping people stay healthy and improving the air quality that they are breathing.

We design our products to help keep you and your family safe by filtering out the harmful particles in the air.  And, it is our mission to make quality air filtration products available to all consumers and frontline workers.

Thanks for checking out how to change a furnace filter. For more information about Filti, our washable air filters, disposable filters, mask products, and our mission, visit our website at or email us at We look forward to hearing from you!

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