The ultimate beginner's guide to PC FANS

[ukpitbull]

hey strange, i havent used them noctas mate , this is first time going micro , my cab siize will be no bigger than 2x2x2.5ft height with 150-200watts of cfl max.

Think that i will be going with a 120mm scythe ultra kaze 2000 or3000
and one of the delta bad boys that someone pointed out early on in the thread , just volt them down init???
Been thinking more clearly about this box in the past few days

 

[ScrubNinja]

Yo Strangely, yeah, I realised I would have to rig up pedal powered fans if I had no electricity! Let's not even discuss the lights.

Norrath, tidy! I like it. Good idea with the thermostat. How many watts?

Pitbull, be aware that different fans handle under (and over) volting differently. When you find the fan you want on Delta's site, open the pdf file for that range, and look at the one you want, and look at the "operating voltage range". The lower the lower number is, the more you can under volt it, I *think*. So if you have a fan with very high dB rating, and it doesn't handle a low voltage, then it's probably not gonna be great for super stealth.

I just looked up my 80mm Delta which is damn loud at 52.5dB and that operates from 7 to 13.8v. I've never actually hooked it up to an adjustable supply where I can choose the exact voltage, but I know that it can be lowered very stealthy with the fan controller, and still spins up at startup etc.

@ anyone reading this: This is the whole essence of speed control really. Why waste hours researching and wading through my guff, and then praying desperately that I wasn't stoned when we talked (I was!) and didn't read some important number etc, and then hope that you nailed your performance:stealth ratio perfectly (and what happens when summer comes?), when you can just buy a kickass fan and cover the whole range from total stealth to high wattage super extreeeeme grow? I do not get it. If anyone can answer this, please go ahead, thank you.

 

[maryjohn]

Scrub I just tried my delta fan to see how low it can go.

the answer is around 5 volts. about 4.9 volts it starts acting funny and by 4.5 it stops.

at 5 volts, it is quiet (not silent), quite strong, and draws .6 amps.

I tried a cold start at 5 volts, no problem. can't go any lower with the fan already spinning than you can when it's off.

 

[ScrubNinja]

Awesome man, we even got a draw rating! I think I'm going to get the model under yours, the PFB1212GHE. 2.7 amps so it will go in my cupboard next run and be controlled nicely by the 3 amp adjustable supply, with overhead. The only thing bugging me is the air fins. I wish there was a model without.

 

[maryjohn]

fiy if you want ones that can be undervolted more, the afb series are supposed to be better.

 

[disfunktional]

hey Scrub would you recommend a thermaltake fan, with a temp sensor, on a 150w HPS? il be a lil tight with the verticle room in my cab and thought that keeping the light cool might help.

 

[ScrubNinja]

Cheers mj! Will look into that.

Disfunk, it depends bro, on the whole situation, just refresh me on what your plan is cos there's so many threads I read and not sure of your overall system! If it's something simple like to vent a cool tube duct with no carbon filter, certainly, I'd say that's a great application for it. Just gotta keep in mind, the thermostat is a one-size-fits-all deal so from memory I think it needs 55* C to hit full speed, and I suspect even a well cooled hps bulb would easily hit that.

If it doesn't reach 55c, it's no big deal but it means it may speed up and slow down, and won't be running at full speed. A little experimentation will be called for - I only set it up in a proof-of-concept way is what I'm saying. (but yes it will work)

 

[disfunktional]

the set up wont be running through a cool tube i was thinking of just blowing on or across the bulb. the dimensions will be 17-5/8"x15"x29-1/2" with a 150 cfm fan exhausting the cab. the scrubber will be located above the light. i wasnt sure if the 150cfm flowing to the top of the cab and past the light would be enough to keep the light cool.

 

[ScrubNinja]

Yeah I'm not certain but from what I've read, always a good idea to put a fan on the bulb in a setup like that. Anyways, yes, it'd be perfect for that. Simply attach the sensor the top of the bulb where it won't block light, and in my ambient temps at least, the fan will run slowly and silently at lights out. When the lights come on, it goes higher. Auto stealth

What is the coolest ambient temp you'd be likely to have?

 

[disfunktional]

im not sure about the coolest ambient temps just yet. i guess i should start getting around to checking that. unfortunately i will have to be keeping this in the garage so im worried about the temp swing. il have to brain storm and figure out how to tackle that problem.

 

[disfunktional]

what would be the ideal cfm blowing on the bulb? 30cfm?

 

[ScrubNinja]

what would be the ideal cfm blowing on the bulb? 30cfm?

Hey bro I've only seen 600s and up with hps, so not dead certain, but just on my instincts, I'd want at least 100 cfm. you could probably go much less but it's seriously hot here, so I always overdo it, and a fan in that position is naturally muffled by the cab. The SFII is perfect for that use, just turn it down if it's too loud/not needed. Specs are all over the shop, but these are from my box and seem about right:

* Low - High speed
* 0.08 - 0.48 Amps
* 35.2 - 120.68 CFM
* 0.94 - 7.78 mm-h2o
* 22.5 - 46.4 dBA

If possible, try to suck your intakes from the very bottom, so it gets cool air from the cold cement/floor. Makes a huge difference imo. I was amazed when I ran lights through the night. In winter my temps only varied I think 1 or 2 degrees between the coldest part of lights out, and the hottest part of lights on. I was sort of worried about it but then I looked it up and found it's desirable! lol

 

[Lord Doobie]

good article...thanks


after reading this, it helped me determine that I'm probably going with one 115VAC case fan

there's a slew on ebay...

 

[disfunktional]

Hey bro I've only seen 600s and up with hps, so not dead certain, but just on my instincts, I'd want at least 100 cfm. you could probably go much less but it's seriously hot here, so I always overdo it, and a fan in that position is naturally muffled by the cab. The SFII is perfect for that use, just turn it down if it's too loud/not needed. Specs are all over the shop, but these are from my box and seem about right:

* Low - High speed
* 0.08 - 0.48 Amps
* 35.2 - 120.68 CFM
* 0.94 - 7.78 mm-h2o
* 22.5 - 46.4 dBA

If possible, try to suck your intakes from the very bottom, so it gets cool air from the cold cement/floor. Makes a huge difference imo. I was amazed when I ran lights through the night. In winter my temps only varied I think 1 or 2 degrees between the coldest part of lights out, and the hottest part of lights on. I was sort of worried about it but then I looked it up and found it's desirable! lol

wow 100 cfm!! as luck would have it i will be sucking air from the bottom of the cab. il be useing the light trap/ intake/ sump cooler/ sump all in one and the intake draws air directly from under the fridge

 

[ScrubNinja]

Doh I forgot about that sump thing, good thinking The 100 cfm is not much really, but it all depends on the situation. I have 93.7 CFM on that 120mm blowing across the buds/lights, plus two more 80mm 30cfm fans blowing straight up - 150 or more cfm, and there is not much air movement on the far right (basically none). So if you had buds growing around the bulb or something, that will all affect it. I ain't even seen a 250 bulb so I have no idea for hps really.



Also, depending on the exact situation, you may be interested in one of the fans like my deltas with the solid fins. I said they are no use to growers but I lied. In a case like I'm picturing yours, a pc fan will blow in the shape of a hollow cone. If you hold your hand over a strong one, you'll feel it clearly. It's because they cool computer chips and shit, up very close, and the motor otherwise creates a dead spot right where they're trying to cool. So that wouldn't be optimal for blowing directly on a bulb. The ones with fins aim the air in tight to more of a straight flow - you can stand across the room and the flow will still be very localized. So I think they would be great for blowing on a single bulb.

Edit: or see the nexus beamair. Someone here bought this after I showed it to them and they were very happy.

Thanks Lord D.

 

[disfunktional]

thanx for the link to the nexus beamair. i think il give that a try, possibly with two fans blowing on the bulb(one on each side).

 

[Strangely]

Alright Scrubninja, a quick ball park figure from your amp calibrated brain if I may? Trying to work out if I can get away with running power from my light circuit in the ceiling up to the loft rather than from the sockets on the first floor (loads more effort).

Circuit is rated at 5 amps. I will be running a 125w cfl, at least 1 thermal take (pos 2 stacked), a smaller 80mm fan on the bulb, possibly a small pump to aerate res. Whaddya reckon? I could drop the pump.

 

[maryjohn]

let's see the cfl takes 1.04a, assuming a 250 watt psu (2.08a) which is more than you need, and we need the watts on your pump.

That will be some pump if it takes you over 5 amps.

you will be fine.

 

[ScrubNinja]

Oh man, I don't even know when it comes to AC, totally not my area! But I would mention to mj that strngly (sorry gotta abbreviate to save time...oops) is on 240v or so, I believe. And also, isn't it weird that you only have 5A? I thought we have 10 in my 240-ish country.

But if you're thinking the amps of the fans count to the AC amps, they don't. It's 12v so they're different amps. See the volts equals amps times blah blah formulas I posted a page or two back.

 

[ScrubNinja]

Amps = Watts/Volts
Watts = Amps x Volts
Volts = Watts/Amps

So the 125w cfl is drawing (at 240v) around .52A.

Edit: which is a roundabout way of saying:

you will be fine.