I live in an area with not so great air quality and no AC. We have little air filters inside the rooms, but at night we have to let the cool (and dirty) air inside to cool down the house.
I’d like a solution to blow air in while also filtering it - but aside from one Amazon listing and makeshift solutions with zip ties, I haven’t seen great options.
Any recommendations you have?
If you’re relying on the breezes to let air in, then a furnace filter that is the same size or a little bigger than the opening of the window should work. You’ll get a little less air, but a HEPA filter will let only clean air in if it’s wedged into the window opening or taped to the outside.
If you’re doing a box fan with furnace filters, do at least 3 filters and some cardboard to make a cube, put the cube outside and the fan in the window opening, and block any gaps around the fan.
It’s a basic box fan with a HEPA furnace filter attached, but it’s all you need.
So, filter the air after it comes in, not in the process of blowing in the window?
Set it up at your window and do both.
Yes, you want to filter on the output side. Putting the filter on the input will put extra strain on the fan motor.
Why will it? Surely it should make no difference?
Filters do slow down air flow.
filters on the output side should still strain the fan motor, no?
No, static pressure against a pump (which technically a fan is) is much less stressful against the motor than limiting the supply is. It’s easier for the fan to push against resistance than it is to pull air through resistance.
And those furnace filters can be found in ALLLL sorts of sizes, you don’t just gotta go with a square one.
If it’s just one room, use a tower air purifier. Mine is set up in my workshop at a window. I cut a piece of fiberboard to adapt the purifier to the window frame, but cardboard works.
I like this method better than the box fan/filter combo because it provides greater air flow and removes pretty much everything with the HEPA and carbon filters. It’s saving my sanity right now with all the pine tree pollen and smoke from debris pile burning.
For a whole home, place a window fan in one room pointing out. Then put air filters in the windows of other rooms. This has the benefit of keeping the noisy fan in an unoccupied room while you’re trying to sleep. Alternatively, if you have an attic, you can get a fan that fits the attic access. This works better because you’ll be cooling your attic as well. You can also consider a dedicated attic fan which can knock 10 degrees off the inside temperature on a hot day.
I like the portable AC units, you get AC AND filtering.
Just make sure you get a dual hose version. One hose is air intake, other hose is air exhaust.
$500, 14,000BTU
Edit Apparently automod hates the links Amazon generates in their apps. Had to get un-banned.
Let’s see if it likes the normal Amazon link better:
Portable AC units suck. Window AC units are far more efficient
Oh, agreed, but some places limit the use of window ACs.
Fair point!
I have a dual-hose portable AC, because my landlord sucks and won’t install something sensible like a mini-split. My biggest complaint is that the only mode that sucks in outside air relies running the inefficient and expensive AC. I’m in SoCal, so no cheap electricity for me. If I had the option I’d 100% rather install solar, but as a renter that is definitely not an option.
That said if I was purchasing one, I’d buy the one recommended by TheWirecutter. It uses a dual hose-in-hose design and is more power efficient than most models.
A version of that is on sale in the US from Sam’s Club for $375.
Honestly, I’d just throw a decent furnace filter on the intake side of a box fan. Its cheap, effective , and you can easily replace the filter once it gets too grimy.
Maybe you could make a Corsi–Rosenthal Box. They’re pretty easy and cheap. It’s basically just a fan, a filter(s), and some tape.
Though it would be significantly less effective when bringing in outside air than just filtering inside air.
I’ve just bought some HEPA filters and ziptied them to one of those square fans. Works like a charm.
