I keep seeing articles about these and I have to ask: are people actually building them? Sure they work but they’re so ugly. Is it really worth saving $40 for your bedroom to look like a garage?
That wasn't my experience. The day the smoke moved in, I ran to the home store to grab a couple extra furnace filters, and there was a steady stream of people grabbing them, and heading to the box fan section. The secret seems to be out.
What's better? My bedroom having some home built filtration art in it, or the inside of my lungs looking like they've sucked down a lot of forest fire?
If you care that deeply about what your room looks like, great. There are plenty of good looking air filters you can pay lots of money for. I'll spend far less to have a far better filter out of the deal.
I've done box fan filters before, and they certainly help if they're what you can afford or can find in stores, but after enough years of dealing with wildfire smoke this year I invested in commercial units and I am significantly happier.
After doing a fair amount of research, I ended up with a series of Coway units. They're more expensive than box fan filters, but they're smaller and significantly quieter, especially with a sensor-driven auto mode that adjusts fan speed based on detected pollution levels. This means I'm far more willing to leave them on all the time and get the benefits 24/7. The fact that they're multi-stage is a big plus too, particularly with cat hair around. It means that I have to clean the outer charcoal filters more often but the inner HEPA filters only 1-2 times a year. As an added bonus, power consumption is significantly lower than my box fans.
If you let the heavily polluted air in (a few hundred µg/m³), then close the window and set the purifier to maximum power, it cleans the room in ~20-25 minutes.
They also have a carbon layer that's supposed to help with odours and that pollution that can't meaningfully be caught by a simple HEPA filter, although I don't know how effective it is.
In one month of north-west smoke, they got nasty as hell, which is that much less crud aggravating my lungs.
Overall, its not the prettiest and I'd prefer a HEPA filtered energy recovery ventilation but I'm not going to install that in my rental for a couple weeks a year. Usually in Oakland climate the windows are open.
They are louder, use more energy, are less efficient, uglier & cost more money than several store bought alternatives which often include several carbon & hepa filter replacements which is the main expense in building these fans.
They work well in the garage though, and if you don't plan on changing the filters frequently they are the cheapest build option.
Even then, I just keep a big stack of furnace filters handy and swap them regularly. When we got hit with the wildfire smoke last year I put in a new filter every day. More practical than putting box fans around the house.
However, The box fan setup uses a much larger filter and pushes way more air. I only take it out if the outdoor quality is abnormally poor.
Yes it’s ugly and noisy but it’s for emergencies.
Also, you’re saving way more than $40. Wirecutter’s recommended one costs $200.
What is more important to you: superficial nonsense such as looks or your health?
Go ahead and spend the money so your crush pad can retain its splended wonder while the rest of us breath happily along with some extra dough in our pockets.
The custom purifiers always have proprietary filters. That’s where they make their money. It isn’t $40 difference, it’s $40 per year. Often more. And once they stop selling that model, they’ll discontinue the filters and so you’re buying another one. And another. And another. Each with its own problems that you have to live with or shop around for, which means more purifiers purchased while sorting it out.
Then YOU go ahead and do that. My point of arguing your elitist criticism is that some people either don't have or need that extra $40.
It was a stop gap until I could actually get my hands on a large commercial air purifier, those were unavailable at the time.