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Home Maintenance: Clearing the Air, Literally

Air filters - wait - what?? I have to change those? When?


One of the often overlooked household tasks that's really pretty easy is changing the air filter (or filters) in your home. My last home had 2 enormous air filters in the attic. This new one has 3 separate thinner ones scattered throughout the house. Know which one you've got? Here's how to figure it out, and then we'll talk about how to change these, when to change them, and why you should. In your house, you'll see two different kinds of "vents" scattered around. The one you see most are the air vents that force air INTO your rooms. Usually in the ceilings in the warmer states, and sometimes in the floor for cooler states. Mine are all in the ceiling. They are a little bigger than a piece of paper, and the giveaway is that warm or cold air comes out of them when the a/c or heater is on. Those don't have filters.


Somewhere else - sometimes in a wall, sometimes in a ceiling, you'll see larger "vents" that suck air in from your rooms, feed it to the air conditioner or heater, which cool or heat it, and then force the same air back out through the vents in the ceiling or floor. Those are your "return air" vents. There's usually a way to open these, and you'll see a meshy / foamy / sometimes dusty thing in there that fills up the space. The air is pulled through this filter, which removes dust and particles, pet hair, some allergens, etc. Then it sends the clean air to be heated or cooled.

My 14-yo daughter reaching up to change the filter in the return air vent in our kitchen
Opening the ceiling return air vent in our kitchen

This first image is a picture of the return air vent in the ceiling of our kitchen. There are two little twisty things on the side that get loosened to open the grate. She used a screwdriver to loosen them, but sometimes that's unnecessary.


Once you open the grate, you'll see the air filter inside. These usually start out white (or blue in some cases) and when they've outlived their usefulness, they turn grey and yucky. See photo of clean and dirty next to each other.


This is the dirty air filter removed from the kitchen (gross!) next to the clean replacement we are about to install
Dirty air filter (gross!) next to a clean one ready to be installed

Once you look in there and see whether it needs to be replaced, you'll need to know what size to order. Pull the filter out just a little, and on the cardboard surround (don't remove this when you install!) you'll find the dimensions. You can get a new one at Home Depot, or on Amazon, or at any hardware store. You do have to get the right size, though, because if it doesn't fit right, it won't work right.


My son removing the grate from the upstairs return air vent in the wall

My daughter changed the return air vent in the kitchen, and my son did it for the third floor space, so it's not hard. She's 14 and he's 11, so I promise it doesn't require special skills. This will go on their schedule moving forward.


When you buy a new one to install, you need to put it in the right direction. There's an arrow on the side. It tells you what direction the air flow should be. It should point INTO the vent -- not out into the room or down from the ceiling, since the air comes in from the room and through this and into the a/c system.


So - that's done. How often do I do this? Theoretically, every 3 months, these should be changed. You might make it longer, but you should check these. You might need to replace more often, if you live somewhere with a dusty season or with a really heavy pollen season like Houston. The newest filters I bought, and I'll report back on these, are "smart" filters and they have a bluetooth thing on them that lets me know when they're due for replacement. I *think* it can even order new ones from Amazon for me? In the meantime, I'll put a reminder on my calendar to check them in about 90 days.


Why do this? Think of it as a mask (we're all familiar with masks by now, right?) that you're using day after day after day -- if it gets covered with dust and pollen and allergens, it'll become harder and harder to breathe (think of how much harder your air conditioning system will have to work to pull air into itself!) and less and less effective. The cleaner the filter, the better job it can do clearing the air.


I went to buy filters - and there are too many options! Some say MERV 11 and others say something about a performance rating with a number like 1900. The higher the number (on either scale) the smaller the particle it can filter, and the better job it does cleaning the air. Anything from MERV 8 to MERV 13 is available for home use. If you're pretty allergic, go with a higher number there. 3M came out with its own scale (that's the 1900 number scale) and again, the higher numbers correlate to better filtration. I am by no means an A/C expert, so I won't give specific advice here, but use your best judgment, and a new air filter with a lower number is probably better than a really dirty one with a high number.


Next post is on the thick whole house filters - I'll have to run to a friend's house to get a photo of those. And when I install the second floor filter later, I'll video the process and link it here.


This 3M Filtrete "Smart Air Filter" is the new filter variety I got. (I got it for 2 of my 3 filters, since they were sold out in one size.) That gold "button" in the middle supposedly talks to an app on my phone and tells me when I need to replace this. I'll report back. It was remarkably easy to set up, but if you get stuck, message me and I'll tell you what worked for me.


Adding this to the quarterly to do list for the house projects.





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