A serious look at PC fans to power scrubbers.

[Agouti]

I know many people claim that a PC fan is not up to the task of creating enough pressure to effectively make a scrubber work, but I'm looking at this from a different perspective. I recently purchased a fat filter, and am looking to purchase a powerful PC fan to make it function. If this fails, I can always section off a portion of my already small grow setup. and use a blower, but I feel the noise would be too conspicuous.

So here are my thoughts on the matter: because I am using LED lights, cooling is a non-issue. This doesn't have to move enough air to keep it cool; the temperature is just fine. My main concern is smell. Using a passive intake, I wonder, can I generate enough static pressure with a PC fan to filter the smell.

I plan on pulling instead of pushing, in order to keep the facade that my growbox is in fact a normal full size pc tower. What I've noticed, is that not all PC fans are built the same. I feel many of the naysayers are familiar with a .10-.20 amp fans, but what about .5 amp, 1, 2, or even 3 amp fans? Fan technology has rapidly progressed in the past few years, much like LED technology (I can flood the hell out of my case with 2 100 watt fixtures for $300 total).

So my thoughts are, should I keep my CFM in the 75-150 cfm range? (I have a 150 cfm filter), or should I go balls to the wall knowing the static pressure won't be there, so might as well try for the 200-300 cfm range in a crazy 1-3 amp fan?

 

[reasonevangelist]

right there with ya!

Due to my water cooling endeavors, i had to learn a bit about fan pressure, and how some slower and lower CFM fans, are actually much better at producing/maintaining pressure. Some radiators do better with "high pressure" fans, while others are designed for "high flow," and make pressure a non-issue.

Anytime you obstruct or restrict airflow, you need pressure to compensate.

Instead of a DIY carbon-fill can, i was considering something like a multi-fan carbon-sheet stack. If you wanted to go the stack/multi-fan route, yate loons are cheap and typically pretty reliable, but probably not great pressure... which is why i'd want to use several of them. I just don't know enough about the specifics of various restriction mediums or aerodynamics to be able to calculate such things myself, so i'd have to just try it and see how it works.

I'd like to see a "cheapest way to neutralize odor issues" thread.

One problem with using a multi-fan/sheet stack, is that if you have to change either a sheet or a fan, you'd have to disassemble the contraption, which could be a time consuming hassle, and potentially more filter-down-time than would be acceptable.

 

[Spuzzum]

It all comes down to your grow area's cubic foot space... you say you're using LEDs, but not what you're using for space.. ie: a tent, a closet, or a cabinet, etc...

For instance.. I'm figuring a way to filter a DR60 v2.. 2x2x5'.. 20 cubic feet. I was considering a Can-Filter, with a 4" Stealth brand fan.. 175CFM. The fan's louder than a hurricane! Even with a dimmer, it's still going to be louder than I want. I used to grow in a cab, using ac axial fans to exhaust, and my own DIY filter, using a small rubbermade tub and a 2" thick carbon filter sheet I bought from an industrial supply warehouse. I can't find that shop anymore, and the only other shops are charging more than a can-filter would cost to begin with.

But looking at Can-Filter's site, they actually have 2 different models that have "computer fan" as one of the recommended fans to use with it. I was considering the Can-Filter 2600..

Specifications
Max Recirculating (Scrubbing) CFM: 90 cfm / 142 m³h
Max Exhaust CFM: 42 cfm / 71 m³h
@ 0.1 sec contact time
Prefilter: Yes
Mounting: Bayonet or Regular
Flange: 4"

Dimensions: (with pre-filter)
·Outside Diameter: 14cm / 5.5"
·Height: 45.3cm / 18"
·Total Weight: 4.5kg / 9lbs.
·Carbon Weight: 2.1kg / 4.63lbs
Pressure drop at max cfm: 42pa / .20"wg

Recommended Fans:

FAN Watts Consumed Filtered Air CFM

Can-Fan 4" 62 Watts 88 CFM
6" Axial (Computer Fan) N/A 79 CFM
4" Axial (Computer Fan) N/A 39 CFM


Can-Filter 9000

Specifications

Max Recirculating (Scrubbing) CFM: 120 cfm / 186 m³h
Max Exhaust CFM: 55 cfm / 93 m³h
@ 0.1 sec contact time
Prefilter: Yes
Mounting: Bayonet or Standard
Flange: 4"
Dimensions: (with pre-filter)
·Outside Diameter: 14cm / 5.5"
·Height: 60cm / 25"
·Total Weight: 5.5kg / 12lbs.
·Carbon Weight: 3kg / 6.6lbs.

Recommended Fans:

FAN Watts Consumed Filtered Air CFM

4" HO Can-Fan 76 Watts 114 CFM
Can-Fan 4" 63 Watts 94 CFM
6" Axial (Computer Fan) N/A 86 CFM
4" Axial (Computer Fan) N/A 47 CFM



You just need to be sure about the "contact time"... if the fan's too fast, the filter won't work as well. And obviously.. you'll want a fan stronger than what you're trying to exhaust.. the filter will reduce the cfm output.

As for a good fan... Noctua's are the quietest, and the strongest.. with the most static pressure. I'm looking at the NF-A15 PWM for my exhaust...

http://www.noctua.at/main.php?show=productview&products_id=54&lng=en

 

[Cannis]

I run 8" axial fans that are rated at just over 600cfm, I have both 120v and 240v, the 240v is half the amps of the 120v. I think they are 80 watts ea.
http://www.ebmpapst.us/en/products/axial_fans/axial_fans.php

 

[Spuzzum]

I run 8" axial fans that are rated at just over 600cfm, I have both 120v and 240v, the 240v is half the amps of the 120v. I think they are 80 watts ea.
http://www.ebmpapst.us/en/products/axial_fans/axial_fans.php

Mine were 6" axials.. can't remember the cfm or wattage.. I had them on dimmer switches anyways. I'm going with dc fans this time, so I can control the fan with a PWM signal from an Arduino I'm going to be using with my panel. That.. and the DC fans are cheaper than the AC fans.

 

[jijiandfarmgang]

axial fan cfm ratings get thrown out the window under pressure and aren't well suited for that

.....but since your using 200 watts led, how much scrubbing could you actually need?

I'm sure an axial would work fine in your case.

- Jiji

 

[Spuzzum]

axial fan cfm ratings get thrown out the window under pressure and aren't well suited for that

.....but since your using 200 watts led, how much scrubbing could you actually need?

I'm sure an axial would work fine in your case.

- Jiji

That's just it... it doesn't matter how much heat he's exhausting... it's the "scrubbing" of the odours. And as for the CFM getting "thrown out the window".. this is true, but that's with all fans. It's not so much the CFM, but rather the static pressure.. the actual force of the air. In a cab situation, axial fans are completely fine.. and have worked for years. I used to run a push-pull air-cooled hood in a cab, along with an axial fan exhausting through a home made filter using an industrial carbon sheet and a rubbermiad tub. Cut a hole in the lid, framed it with 2"x2", duct taped mesh on the backside, then inserted the filter and duct taped it sealed. The axial fan was mounted on the side of the tub, and exhausted out a 6" duct. I even had all the fans on dimmer switches to quieten them down. No heat problems whatsoever. And no odour problems either.
Axial fans won't work for a filter designed for a room, but even Can-Filter themselves "recommend" axial fans as "suitable" fans to use with at least 2 of their filters.. to a mximum 55cfm "exhaust", or 120cfm as just a "scubber".. ie: filters the room, but doesn't get exhausted. There's a difference.


Btw... Noctua make the best DC axial fans, but Orion make the best AC axial fans... prefered in the music industry for rack cabinets and shit.

 

[jijiandfarmgang]

And as for the CFM getting "thrown out the window".. this is true, but that's with all fans.

Well not exactly. To clarify what I meant, axial fans cfm drastically drops the higher the static pressure. Much more so than centrifugal fans.

- Jiji

....and thats just for the record. If your using a cab, personally not my thing, but yeah I would use axial.

 

[Spuzzum]

Well not exactly. To clarify what I meant, axial fans cfm drastically drops the higher the static pressure. Much more so than centrifugal fans.

- Jiji

....and thats just for the record. If your using a cab, personally not my thing, but yeah I would use axial.

I guess I learned something.. I actually thought it would increase. I just compared a few Noctuas, and sure enough.. they dropped. But either way... they still do the job for what he needs. A cab may not be your thing, but a DR90, a 3x3x6 tent, is all a lot of people really need. That's 54cfm.. Can-Filter 9000. They recommend 2 different axial fans..

6" Axial (Computer Fan) N/A 86 CFM
4" Axial (Computer Fan) N/A 47 CFM

My "cab" by the way... was an 18 plant SoG, in a 3-stage 6 plant rotation once a month... under a 250hps, I was puilling out 6 18"-22" plants, averaging 20g's per plant, every 3-4 weeks. That's a qp per month, out of a "cab", with a growth chamber area of 36" x 18", and 24" from the top of the hydro tub to the bottom of the glass of the hood. It's all one person really needs... unless you're growing for ca$h.

I have my licence.. but I'm only allowed 10 plants. That includes clones, vegging, and flowering. A 2 plant rotation every 3 or 4 weeks is all I'm going to need. I can do that in 2 DR60's.. 4 plants in 1, 4 babies, and 2 clones in the other. Puting them side-by-side, I'm also housing my hydro reservoir in the 2nd tent. I plan on modifying a bit. Slightly.

Living in a bachelor suite, you have to do what you have to do. Not eveyone's in a house... with an extra room or basement.

 

[jijiandfarmgang]

That's a pretty respectable yield considering circumstances.

It's all one person really needs... unless you're growing for ca$h.
.

Don't forget there are many of us growing for multiple medical patients as well.

- Jiji

 

[Spuzzum]

That's a pretty respectable yield considering circumstances.



Don't forget there are many of us growing for multiple medical patients as well.

- Jiji

You're obviously the better man then... lol.

 

[bushrider]

Check out the blower thats sold by Steves Leds. Its basically a computer style centrifugal fan. You would have to custom make a mount to attach to the Phat filter but that should be pretty easy. You may need more than 1x blower for the CFM required ....

http://shop.stevesleds.com/Pressurizing-Cooling-Fan-with-Power-Regulator-Pressurizing-Cooling-Fan-w-plug.htm

This fan actually makes less noise than the powerful Nocuta's. Its an OEM part from a Sony TV, so its meant to be practically silent. Compared to a Noctua with similar power consumption the CFM is about 1/3rd but the static pressure much higher. I have been considering building a scrubber using these fans.

I'm planning to build a drying box with a carbon filtered exhaust using one of these fans.
It will be used for several days of darkness before harvest and then for drying. If that works out then a scrubber using 3 or 4 of these fans.

 

[Mellowman2112]

I know many people claim that a PC fan is not up to the task of creating enough pressure to effectively make a scrubber work, but I'm looking at this from a different perspective. I recently purchased a fat filter, and am looking to purchase a powerful PC fan to make it function. If this fails, I can always section off a portion of my already small grow setup. and use a blower, but I feel the noise would be too conspicuous.

So here are my thoughts on the matter: because I am using LED lights, cooling is a non-issue. This doesn't have to move enough air to keep it cool; the temperature is just fine. My main concern is smell. Using a passive intake, I wonder, can I generate enough static pressure with a PC fan to filter the smell.

I plan on pulling instead of pushing, in order to keep the facade that my growbox is in fact a normal full size pc tower. What I've noticed, is that not all PC fans are built the same. I feel many of the naysayers are familiar with a .10-.20 amp fans, but what about .5 amp, 1, 2, or even 3 amp fans? Fan technology has rapidly progressed in the past few years, much like LED technology (I can flood the hell out of my case with 2 100 watt fixtures for $300 total).

So my thoughts are, should I keep my CFM in the 75-150 cfm range? (I have a 150 cfm filter), or should I go balls to the wall knowing the static pressure won't be there, so might as well try for the 200-300 cfm range in a crazy 1-3 amp fan?

Were you able to make the pc fan work with a little can filter? I'm interested to know as I am designing a tv stand/grow box. Would love to be able to use a pc fan. .