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Ceiling Air Purifier

jefftk.com

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Re: Ceiling Air Purifier

#51

Post by lkbm »

0daystock wrote: post #23

That looks extremely cheap and ugly, I would be embarrassed to have company over. I'll stick to my True HEPA Coways, which you can get for roughly the same price as this DIY contraption.

High ceilings will help. Next step would be to add paint the joints and latticework (or run some colorful tape), and maybe add some LEDs.

Black light tape along the latticework, black light at the top of the room. Other lighting is all dim lighting in the lower half (warm lamps).

I dunno. It'll be hard to make this not look weird unless you do something crazy, like a drop ceiling so the fan and filters are inset. If the aesthetics are important, I'd put it on the home office (out of view from Zoom) rather than the living room.

Re: Ceiling Air Purifier

#52

Post by blagie »

I think people are missing the point. YES this is bad engineering for a finished product:

- The fan is not designed for high static pressure. It won't do well pulling air through filters.

- It's ugly. It will get uglier as filters get dirty.

- It's expensive to replace filters.

- Etc.

But it's not a finished, industrial project. It's a prototype. Those sorts of issues are universal for prototypes. They're easy to address:

- Switch to a rotor design with higher static pressure

- Provide prefilters. Ideally, there's a nice cover, followed by a washable pre-filter, followed by a carbon filter, followed by the fancy high-filtration filter.

With an appropriate frame, it could be beautiful -- nicer than a normal fan. The filters could actually reduce noise. The frame could guide air (much as in a Vornado), increasing airflow.

Good job OP. It's a clever idea and a good design. It's a proof-of-concept implementation, but that's the point of a proof-of-concept.

(Unless you like the DIY aesthetic, which some do)

Re: Ceiling Air Purifier

#53

Post by titanomachy »

formerkrogemp wrote: post #45
jefftk wrote: post #37

Earlier quoted context omitted.

If you're doing one filter per box fan, I'd go with a MERV-14: https://www.jefftk.com/p/merv-filters-for-covid

This is very similar to what hobbyist mushroom growers use in our setups to inoculate substrate in a 'sterile' environment. Other methods include using sterile, hot oven air, buying very expensive equipment, and making a still air box at home with a plastic tote box. Good times.

In college we used to work under a bunsen flame, is that not enough space?

Re: Ceiling Air Purifier

#54

Post by LinuxBender »

lkbm wrote: post #51
0daystock wrote: post #23

That looks extremely cheap and ugly, I would be embarrassed to have company over. I'll stick to my True HEPA Coways, which you can get for roughly the same price as this DIY contraption.

High ceilings will help. Next step would be to add paint the joints and latticework (or run some colorful tape), and maybe add some LEDs. Black light tape along the latticework, black light at the top of the room. Other lighting is all dim lighting in the lower half (warm lamps). I dunno. It'll be hard to make this not look weird unless you do something crazy, like a drop ceiling so the fan and filters are inset. If…

I going for aesthetics I might just put them in the ceiling and have what appears to be low profile vents that one might not even notice. That would keep most of the noise in the ceiling. One could build an enclosure that the HEPA filter unit sits in and routes the intake/output to different ceiling vents.

With a little extra effort the filter could be swapped out by removing/lowering the vent intake.

Re: Ceiling Air Purifier

#55

Post by kolencherry »

sha256sum wrote: post #6

Great idea. What's worked for me is simply taking a 20"x20"x1" filter and sliding it into the back cover of a standard $25 Lasko box fan. Cheap, easy option for air filtration in the home.

Yes! This is the basis for the Corsi-Rosenthal Box [1]. Five 20"x20"x1" filters and a box fan, with duct tape to seal the edges. Not the prettiest, but it's effective.

[1] https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box

Re: Ceiling Air Purifier

#56

Post by malfist »

foobarian wrote: post #38
malfist wrote: post #35

Earlier quoted context omitted.

I've always heard this, but I don't know that that's true. The thing that dies first on an HVAC system isn't the motor, it lasts a long damn time, it's the capacitor, or contactor or some other fault not really related to the motor work load. Plus, your "motor" isn't an engine, it's not variable speed, it only has one "hardness" that it works at. It might push less air with the thicker filter, but it's not going to r…

>Plus, your "motor" isn't an engine, it's not variable speed, it only has one "hardness" that it works at. This is incorrect - electric motors draw more current when under load. I would suggest researching this or playing with some toy electric motors run from a battery through a current meter.

I have a degree in electrical engineering, thank you for telling me to do my research, I spent four years doing that.

Sure, some motors have characteristics that can be tweaked to run at different work loads either with PWM, or allowing them to pull more amps to drive higher loads. Hell, you can even overvolt them and make them actually work harder.

That's not how HVACs work though. Have you ever opened one up and did a repair? The circuitry is dead simple, there's no current limiting setup or PWM to control how much the motor is pulling or spinning, there's no CFM measuring device to give the motor more volts or a higher amp limit.

The motor is simply pushing air. Air isn't something like a solid load where a motor might lift something or move a lever or gear, it's fluid. The motor is going to run at max and be done.

Re: Ceiling Air Purifier

#57

Post by maxk42 »

Is nobody going to mention what a pain in the ass it would be to change all those filters regularly? I love in a somewhat dry and dusty area and need to change my filters (near the ground) every two to three months. I'd hate to have to climb up a ladder to change eight to nine filters that often.

Re: Ceiling Air Purifier

#58

Post by jefftk »

flybrand wrote: post #48
sdflhasjd wrote: post #20

Earlier quoted context omitted.

It's not clear how this performs over having no fans and filters at all.

Agreed - and another wish list item would be a basic room air purifier “RAP” off the shelf, sitting in the corner. OP will also want to track performance over time. How long does it take the filters to load.

The first chart in the post compares performance against a RAP (Coway AP-1512HH Mighty, the Wirecutter's top pick): https://www.jefftk.com/mighty-vs-ceiling-decay-big.png

Re: Ceiling Air Purifier

#59

Post by jefftk »

jstream67 wrote: post #11

Neat idea however air filter changes would be extremely expensive as its about 5x the air filters of a conventional purifier - which already seem to cost around 50-100 dollars to replace.

The filters are MERV-14, not HEPA, so they're much cheaper ("materials for one fan are nine MERV-14 filters for $110"). See https://www.jefftk.com/p/merv-filters-for-covid for why MERV-14.
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