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  • Writer's pictureRebecca Weaver

HVAC Filters

Updated: Nov 30, 2023

What's A Filter?

If you have heating and cooling equipment in your home, regardless of what kind, it will have some sort of filter. This filter can be made of a variety of materials, and will usually looks like this:

These filters are made of metal mesh for easy cleaning and reuse. Just hose them down, dry them off, and you're all set until next time!
Reusable, Washable Metal Filter
HVAC filters can also have pleated, compressed material. This is a very common syle, but you do have to throw it away and replace it with a clean one when it's time to change them out.
Disposable, Pleated Air Filter
This HVAC filter is the most popular, and in our opinion, the best bang for your buck! The cheapest of the options, this is going to allow your unit to breathe without letting a bunch of dust and dirt through.
Disposable, Carbon Fiber Air Filter

How Often Should I Change My Filter?

Filters, with the exception of electric ones, will need to be cleaned or changed multiple times each year. The frequency depends on the size of your home, household, and animals, along with some seasonal factors, like dust and moisture. It's a good practice to monitor your filter, checking it each month. If it has a dusty film on it, it will need changed soon. If it has a blanket of dirt covering the side, it is well beyond needing changed. We typically recommend changing it between 3 and 6 months, and writing the date on your new ones to keep track of how old they are.

Why Do I Need A Filter?

Most people know to change their filters, but not many people understand why it's so important. HVAC systems draw in air from the home through a duct return. A filter is a thin barrier that prevents dirt and dust from entering the unit, keeping the fan, motor, and coil clean and able to work efficiently. If no filter is used, these components will get filthy, and dirt will be allowed to pass through the unit. Over time, this will cause parts to corrode or gum up, and could cause the unit to burn through parts and need replaced sooner than normal. The filter's job is to protect the internal parts of the unit and prevent this kind of damage. It allows air to pass through while catching all the pollutants, dust, and grime before it enters the unit.

How Do I Change My Filter?

Changing your filter is super easy once you know how to do it correctly. Follow these steps to know what to look for when changing your filter, what's normal, and when to worry!

1. Locate your filter

Filters will be in the return air ducts going to your unit. If you do not know which side your return air duct is, check the ducts attached to your unit. If you find either a slot 1 to 4 inches wide, or something that looks like this, you've found your filter box!

If there is no filter in your filter box, and you do not know how long your unit has gone without one, it would be best to have the unit cleaned out and checked for any issues. Filters can get pulled into the fan once they get too dirty because the air can no longer pass through, so if you suspect it may be super dirty or a filter may be stuck inside the unit, call an HVAC company. They will check all the components to ensure they are working properly, and clean up any excessive dirt and dust that entered the unit when the filter was not there.

Filters can also be in return vents (as pictured). Look for a vent higher up on your wall or on your ceiling that looks larger than the rest of your vents. This is your return vent, and some systems are set up with filters at the vent rather than closer to the unit in the ductwork.

If you cannot find your filter, and do not believe you have one, it would be best to have one installed. Filters will keep the inside of the unit clean, and prevent damage caused by dirt. Without a filter, you run the risk of ruining the unit and having to replace it much sooner than expected.

2. Purchasing A New Filter

Make sure you know the size of your filter so you know what size you need to purchase. The size should be on the side of the filter you currently have in place. If not, measure the dimensions of your ductwork. Typical sizes will be 16x20 or 16x25, but they could be slightly different depending on your situation. Most hardware stores, like Lowe's or Home Depot will have filters available for you in store, but if you prefer online options, Filterbuy is an excellent choice that's easy to use.

We recommend the TruBlu brand. They're inexpensive and they work great! Honestly, the cheaper the better when it comes to filters (you don't hear that very often, but in this case, it's true). Big name brands might tell you expensive filters help with allergies, but they won't do much more than a cheap one. Remember earlier, when we mentioned a filter is designed to let air pass through freely while trapping all the dirt and dust and crap in your air? Well, generally speaking, the more expensive the filter, the thicker it tends to be. So while your filter may be fantastic at collecting what it's supposed to, it also causes air movement to slow way down. There are much better ways to purify the air in your home than with a filter that decreases the efficiency of your furnace or air conditioner.

If allergies or germs are a concern for you, try an Air Purifier. They're great for keeping your air clean, especially during pollen season! This link will take you to our trusted brand, Aerus, to learn more about their Air Scrubbers:

3. Remove The Old Filter

Removing the old filter may be really easy, or you might need to use something to help you. Either way, it's alright. Remove the entire filter from the unit and check it to make sure there are no tears. Observe the amount of dirt on the filter as well, holding it up to the light to see if any light passes through. If you do not see any light, it's a good thing you're changing it! Filters that are left to get too dirty will suffocate the unit of air and cause the unit to freeze up! The coil will become a block of ice!

If you notice any pieces missing, listen to the unit when the fan is running. If there are any abnormal sounds coming from the unit, get it serviced in the near future. The pieces may have gotten stuck and could be limiting the efficiency of your unit.

If you have a reusable filter, wash it off with a hose and make sure it is completely cleaned off.

If you have an electric filter, make sure it is working correctly. There is usually a light that will flash or light up green when the filter is working correctly.

4. Place The New Filter

If you have a reusable filter, return it to its slot so that it fits the width of the duct.

If you are using a non-reusable filter, write the date on the top side of your new filter. This will help you keep track of when you last changed it and when your unit is due for another clean one. When you place it in the slot, make sure it is facing the right direction. If there are arrows, these indicate what direction the air should travel through it. As we mentioned earlier, your filter is on the return air side, so air will pass from the ductwork to the unit. Place the filter so the arrows are facing toward the unit.

Once this is done, make sure the entire width of the duct is covered. If there are any gaps on the sides, you have either placed it incorrectly or need a different size filter (refer to step 2 above).

5. Make Sure It Is Correct

Listen for any rattling or shaking noises from the filter. If you hear such noises, try adjusting it to mitigate these noises.

No noises or frequent movement? You're all set and can carry on with your day!


You now know how to correctly change your filter, what to look for, and when it's serious enough to call the professionals. We hope you found this helpful, and look forward to your feedback!


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1 Comment

Unknown member
Apr 10

As someone who suffers from allergies, maintaining clean HVAC filters is essential for me. Thankfully, HVAC Contractor Riviera Beach company offers reliable filter services that have made a significant difference in the air quality of my home.

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