DIY Air filter boxes / fan enclosures (pics)

funkywizard

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Jan 15, 2017
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Please forgive the "1.0 prototype" made out of cardboard. Wanted a quick proof of concept -- it's being replaced with the 2.0.

Anyway, bringing in outside air for cooling miners is "effective", but tons of filth gets all over everything pretty quick. So, putting together some fans + filters to keep the worst of it from coming indoors.

The "2.0" version is about half done. Need to drill holes in the plexiglass for the fans.

Enjoy! Comments welcome.

20180312_023214.jpg 20180312_023123.jpg 20180312_023103.jpg
 
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funkywizard

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not sure how well this stuff works, plus its a bit expensive. but it might be a solution to investigate.
https://smile.amazon.com/PollenTec-...20857911&sr=8-1&keywords=screen+filter+window
Interesting.

For what it's worth, went with the green filters primarily to minimize pressure loss / airflow resistance. Didn't see any specs for the one you listed. I can consider other filters, depending on the specs.

The relevant specs are:

% filtration efficiency at different particle sizes
pressure drop at varying cfm of airflow
maximum rated airflow

The "cheap green filters" are pretty decent on the last two items, and not very good on the first item, especially for small particles, but should be adequate for the majority of larger particles. Will see how it goes when it's up and running.

The bedroom I'm mining in is --filthy-- from the outdoor air. Every surface gets covered in dirt within a couple days of cleaning them off.

I've actually got some industrial grade clean room hepa filters I can use, but I don't want to immediately clog them up with large particles that a cheap filter like these can handle. Once I have basic filtering in place, will clean up the room and all the servers, so I can see if it makes a big difference in how quickly the room gets dirty again.
 
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azev

Active Member
Jan 18, 2013
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do you plan on putting this on the window to filter air from outside ?
 

Godfr33

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Jan 20, 2018
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Yes indeed.

Just be careful cutting those filters! the fiberglass is really nasty on those..

I have a system adapted from the California Medicinal narcotic plant guys! I figured that they have battled harder than us in the KWh use, heat and filtration department.
So I went to my local (in SoCal) hydroponic store and asked a bunch of questions.

As far as your fans are concerned, I figure they are PWM but what is your projected kWh total vs. CFM

Also what size are the fans, type of static pressure do you think they produce?
 

funkywizard

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Just be careful cutting those filters! the fiberglass is really nasty on those..

I have a system adapted from the California Medicinal narcotic plant guys! I figured that they have battled harder than us in the KWh use, heat and filtration department.
So I went to my local (in SoCal) hydroponic store and asked a bunch of questions.

As far as your fans are concerned, I figure they are PWM but what is your projected kWh total vs. CFM

Also what size are the fans, type of static pressure do you think they produce?
Yeah fiberglass isn't loads of fun. Hopefully will work ok, but either way better than the nothing I've been using a couple months now.

The fans I've got I'll have to check when I get home but I believe each one is rated for around 200cfm, something like 2" static pressure, 20w - 30w each at full speed (lower figure is with little or no pressure, higher figure is with higher pressure).

I picked these out with the idea of using them with clean room filters that have a non-trivial amount of pressure loss. Kind of overkill for using in a wide open window. There is a really reasonable curve between CFM vs pressure, so they provide useful airflow and performance per watt with a decent range of possible pressure losses. Checked a few dozen spec pdf's on delta's website before settling on these.

Right now just running them all max speed and they SCREAM. You can hear it from across the street. It's only tolerable in my apartment because I installed a bunch of soundproofing in the "mining bedroom".

They are PWM, so ideally I want to put these on a thermostat-managed-controller. Any ideas for that?
 

funkywizard

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Attached is the PDF specs. Was able to find these on ebay shipped from China. Took forever to arrive, but were cheap and most were in good condition.

Looks like max pressure is 1.17" (zero airflow), max airflow 210cfm (zero pressure).

At ~0.3" pressure, ~180cfm
At ~0.4" pressure, ~160cfm
At ~0.5" pressure, ~150cfm
At ~0.6" pressure, ~120cfm
At ~0.8" pressure, ~80cfm.

So pretty good cfm rates between 0.3" and 0.6" pressure losses.

At lower pressure losses, there are more efficient fans in terms of cfm per watt (or run these slower than the max of 6000rpm)

At higher pressure losses, you'll want a fan that has a higher maximum pressure.
 

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marcoi

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Apr 6, 2013
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I'm assuming you have two windows on two separate walls? So you can get the air to come in and out?
You may be able to get two window fans and get them into push /pull configuration with air filter in front of the pull.

You can also get a crazy window fan like this to get pressure up.
https://www.walmart.com/ip/Air-King...se-120V-3-Speed-Window-Fan-Gray-9166/32328595

most likely over kill though.

Thats what I would do to keep the air flowing and noise levels down. I would just get a filter big enough for your intake fan and seal the rest of the window off with one of those winter kits
https://www.walmart.com/ip/Duck-MAX-Heavy-Duty-Shrink-Film-Window-Kit-Indoor-3-Pack/21950036
 

funkywizard

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Here's a shot of the specs on the filters:

615 CFM / 0.02" resistance
920 CFM / 0.04" reisstance
1230 CFM / 0.08" resistance
1535 CFM / 0.13" resistance
2085 CFM (max rated airflow) / 0.26" resistance.

So at anything 75% or lower than the max rated airflow, the deltas I'm using will more or less operate at their maximum rated airflow. Let's say 200cfm each if I have fewer than 8 deltas per filter.

I'm planning for 6 deltas per filter, 2 filters, so roughly 2400cfm and 0.08" resistance. Given the low pressure losses, expecting these to be closer to 20w each rather than 30w. I'll go killawatt my "1.0" setup and report back.

SkypePhoto_20180312_101534.jpg
 

funkywizard

mmm.... bandwidth.
Jan 15, 2017
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63
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I'm assuming you have two windows on two separate walls? So you can get the air to come in and out?
You may be able to get two window fans and get them into push /pull configuration with air filter in front of the pull.

You can also get a crazy window fan like this to get pressure up.
https://www.walmart.com/ip/Air-King...se-120V-3-Speed-Window-Fan-Gray-9166/32328595

most likely over kill though.

Thats what I would do to keep the air flowing and noise levels down. I would just get a filter big enough for your intake fan and seal the rest of the window off with one of those winter kits
https://www.walmart.com/ip/Duck-MAX-Heavy-Duty-Shrink-Film-Window-Kit-Indoor-3-Pack/21950036
2 standard box fans weren't doing the job, so I upgraded the exhaust a while back to 6 deltas and one boxfan, and then a boxfan on the intake pointed up to get some cool air towards the higher servers. Worked pretty good but want to filter dust. Also, starting to get warmer outside so I need something heavier duty.

My "1.0" setup actually made things worse for cooling (replaced the intake boxfan with 6 deltas and a single filter -- probably because I'm no longer shooting the air in a useful direction, and the window isnt as wide open with the new setup. Will hopefully address that with "2.0"
 
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funkywizard

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Jan 15, 2017
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Photos:

Intake "filter 1.0"

Outflow is similar to my original setup, but I kludged on another 3 fans until I can get another rackmount fan kit and fix the intake.SkypePhoto_20180312_102718.jpg SkypePhoto_20180312_102714.jpg
 

funkywizard

mmm.... bandwidth.
Jan 15, 2017
825
376
63
USA
ioflood.com
I'm assuming you have two windows on two separate walls? So you can get the air to come in and out?
You may be able to get two window fans and get them into push /pull configuration with air filter in front of the pull.

You can also get a crazy window fan like this to get pressure up.
https://www.walmart.com/ip/Air-King...se-120V-3-Speed-Window-Fan-Gray-9166/32328595

most likely over kill though.

Thats what I would do to keep the air flowing and noise levels down. I would just get a filter big enough for your intake fan and seal the rest of the window off with one of those winter kits
https://www.walmart.com/ip/Duck-MAX-Heavy-Duty-Shrink-Film-Window-Kit-Indoor-3-Pack/21950036
Latest pics show "hot aisle cold aisle" -- two windows on the same wall with the rack of hardware in between them.
 

Godfr33

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Jan 20, 2018
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I'm using a 6' Hyperfan through a charcoal scrubber

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