The ultimate beginner's guide to PC FANS

[ScrubNinja]

I was wondering about your stacking thoughts Scrub. I kept coming up with one main advantage of just spaced stacking - the second fan wont have to work as hard and would thus be quieter. Putting a filter in between would seem to make more sense in getting the most from both fans.

Something to remember is that the first fan is muffled/silenced by the carbon in a push/pull setup. My thoughts on stacking - I look at it like I look at active intakes - sure it may technically work occasionally but it's a black art. I would incorporate it into a design only after I'd exhausted (get it?) all other opportunities. I.E a better fan or a push/pull like mine.

Hey man I thought you said I had ages to do it? lol. No worries anyway, I haven't forgotten, I've just had issues with the new cab and making a new new one. All good. One thing though, I have a diy filter completely different design from commercial filters, but it'll give you a close enough idea.

Architechno, you never know. I noticed all my fans have the gap so I'm thinking the gap is beneficial. If you do want to try it, I would suggest double sided tape with only one side peeled off, cos the gap is about that thickness.

 

[Strangely]

Hey man I thought you said I had ages to do it? lol. No worries anyway, I haven't forgotten, I've just had issues with the new cab and making a new new one. All good. One thing though, I have a diy filter completely different design from commercial filters, but it'll give you a close enough idea.

ha ha yeah no rush, just wanted to gently remind in case you had forgotten altogether! What with our community not being especially well know for our memory retention!!

And yeah a rough idea is all I'm after, even if it's PC dimensions we're talking about. A single fan does appeal more (than stacking 2 in some way) to my mental neatness/OCD gene anyway. I was just musing, whilst contemplating (trying to put off) insulating my loft!

 

[microgram]

narrowing the gap will give better results, but good luck getting it right. Like scrub has said, if it could have been done, it probably would have.

CFM is certainly not a myth . One needs more cfm out than in, which is certainly a proven point. Comparing the fans by CFM and neglecting obstacles is pure ridiculousness. It's like comparing a screw to a metric screw. Two totally different things, even though one would think they're the same.

The less you have in terms of space consumption is definitely a win in a microgrow. I believe efficiency should be the name of the game for all things profitable.

 

[ScrubNinja]

Yeah it's the idea that the cfm rating is realistic, it's not. I'm not much of a mathematician, but maybe a system could be made where you divide the CFM by the mm-h2o and then look at the number on a scale....something like that? I think it would be great if we had some kind of graph to look at and see "oh I have 100w of cfl, so I will need approximately x amount on the fan scale". Something like that.

If it helps, Strangely, with 2 fans push/pull through about 1.5 inches of carbon, with 220w pll I think I got 6 or 7 degrees F above ambient on full speed but I didn't have things sealed up to full efficiency. I'll still do that single fan test for you though. You can always just look at CFL grows too. Ask questions and people will tell you what fan they use and how the temps are. It will take a while because I have to wait until my babies can take that much light.

 

[Architechno]

HEY

This fan is $5 at CompUSA
http://www.thermaltakeusa.com/Product.aspx?C=1190&ID=1732#Tab0

Max pressure is 5.3
Max CFM is 21

The graph on the first page shows how cfm changes according to pressure.
The important thing to remember is that this is $5 per fan, and it's TINY.

 

[ScrubNinja]

Archi, I guess it would be okay in the right application. I would say it's still just a .18a fan, but for stealth I guess you do need to look at lower numbers. I look at a fan, even a computer fan, as an investment, and every bit as important as the lighting or strain, so not too concerned about cost although I know cost matters sometimes.

Strangely. Got your back, bro. I did some heat tests. A little rushed but will still give you a firm idea to aim for.

2 x 55w PLLs and 13w fluoro tube = 123w of fluoro lighting. I forget if you were pushing or pulling so I am pushing because it's more stealthy and you can get away with it with a higher pressure rating fan like mine. Your temps will most likely be better if you pull. Temp sensor is about 10cm from the light and shielded from direct light. There is about an inch and a half of carbon and kitty litter crystals in the filter and the surface area is just under 21" x 14". (Imagine if you cut out the inner screen of your carbon filter and laid it out flat - this would be your surface area)

I started the test on 6v. Ambient was 77.9 and cab temp got to 84 before I decided it's too hot so I switched it up to 7.5v early. Test wattage had been running an hour and a quarter at that stage.

It dropped quickly to 83.8 (ambient 78.8 - difference 5F) and stayed there for half an hour. Now, the volume: Remember my fan is tucked away in a box and muffled by the carbon. On the left of my monitor is the cab, and on the right is my cheap low level, relatively quiet gaming pc tower. The cab at 7.5v is only juuuust louder than the desktop and in general is very quiet and I think fine for your situation. When it was on 6v it was overpowered by the desktop.

So onwards we go to the 9v setting. There's a bit of a jump in the "whirrr" sound but may still be ok for you. The desktop can still be heard but the cab is clearly louder in volume. After 25 mins, temps were 83.6 (ambient 79.5 - difference 4.1)

Now my girls need water so I'll skip the 12v test as it would be too loud for you I think. Hope that gives you some ideas!

 

[ScrubNinja]

One thing to keep in mind, you can generally have them further away from the bulbs with PLLs it seems. To give you another reference point, I left those lights in, went back to 4.5 volts (near silent) with 2 fans push/pull but without the lid sealed - losing efficiency, moved the temp sensor to where the plants actually are (see old pics for distance)



Ambient is 80.9 and cab temp is 78.9. negative 2 degrees.

EDIT: LOL sorry, I unplugged the PLLs after running the test so they weren't on in this last example, haha. :

 

[ScrubNinja]

Strangely, I found some much more relevant figures in Red's rubbermaid thread. He ran 252 watts of CFLs, with the previously discussed ventilated heat shield, and used

The lighting chamber is cooled by a computer fan pushing about 38 CFM. The exhaust air comes out at about 82-84F, but there is little heat transferred to the grow chamber. The lights run about 90F inside the lighting chamber.

The grow area of the box is ventilated by the scrubber with about 10-15 CFM. The air temperature exhausted is about 1-2 F above ambient. The air exchange rate is optimal to provide fresh air to the plants while not stressing the plants out by drying from too much air flow.

So your situation is absolutely do-able. Be sure to check it out. click

 

[Strangely]

Give that man a Gold Sticker and a pat on the head! Cheers Scrub, very good of you.

My proposed little cab would be smaller than yours as well so it 'sounds like' (did you see what I did there) it should be doable. I think your point on venting the light separately is the key isn't it, stop the problem (pretty much) before it starts that way. I'll have a little play in Illustrator again and post up the smaller revised cab visual for general pointing and laughing purposes. I'll also check out Red's thread there, think I might have had a bit of a look before.

Which reminds me, I read your thread where you had the CFls gradually increasing in wattage and the egg fried reflectors going on! I had started it ages ago before I had began 'operation tap Scrub up for loads of info', funny finishing it now!

 

[ScrubNinja]

No probs matey. I think a lot of people have the same worries about how much a fan is actually going to cool so it may help them too towards a ball park idea.

I'll probably be glass hooding my cab at some stage - I had planned to originally. Most of my new cabs will probably have glass hoods. Got some glass (actually off a real heat shield) that fits very nicely in my old PC which I'm slowly rebuilding. One thing you should factor into your design is the ability to remove the hood quickly and easily because I heard they get dusty quick. The dust blocks lumens.

It's a good idea to start the lights low I think In every other regard - food, water, pot size, soil etc, it's always recommended to start light/small/less so I think it's good for the light too. Then again I got a pretty shitty yield, lol.

 

[Strangely]

Design 1438...

Design 1438...

Alright Scrub!

Good shout on the 'easy in and out' glass shield. I was thinking of going to the tip and pinching a glass shelf from an old fridge (in the ghettooooo) as I think these fellas are toughened for when I inevitably drop it. I'll check for any additional lumen loss it might mean.

Here's the latest design.

Pertinent points/questions...

1. Light section
- Could I get away with a smaller 80mm fan here? I was thinking stick to 12omm and run it right down power wise, so I have a spare if the main fan packs in.
- Do you think I should just do a light trap here as well? If I do that I may as well 'fill in' the space for extra plant area between the light traps on the back if you get what I mean!

2. Sizes stack up do you think?
- 'Seems' a good bit smaller than the one you have pictured you did the tests with, I've also done my calculations (stop laughing at the back) so the internal light traps don't bottle-neck at all.

Right it's time...

 

[ScrubNinja]

Yes that's the basic idea you're after although you don't need to lose half your grow height to other stuff. I would look at having lights at the very top, and the heatshield directly below. Then on a wall just below the heat shield, place a carbon filter and fan so it only blocks a tiny part of the space, and gives you a lot more head room.

An 80mm fan is going to be louder pushing the same amount as same spec 120mm. I can't really say any more because I really don't know if it'd do the job. You can purchase 80mm to 120mm fan adaptors if that lets you experiment.

Wait, do you mean for the mom cab? I'm a little confused to what some of the square boxes are. With the example I just gave about setup, I would exhaust both grow rooms with the one fan, going thru scrubber. Have intakes for both rooms but with a passive hole and light trap between. And some kind of sliding door so you can adjust the ratio of cooling between rooms (just in case you screwed the calcs). Actually now I read back, I think that's what you drew there, LOL.

Looks like a good sized box but just aim to get more space for the plants Also, I've found that cooling an amount of light in a bigger cab is easier than cooling that amount in a smaller cab.

I think that covers everything. If I get inspired I'll try to draw something out. Peace.

 

[Strangely]

I'm thinking sort or PC size with the scrubber on top. I need a very small cab for wife sign off!

I'll have another play on sketchup to try and do a clearer visual.

 

[ScrubNinja]

1000 words

1000 words

A light trap I made out of aluminium angle and would suit you very well:

 

[Strangely]

Ooh I like the idea of an intake fan for the light section. Although I need to watch number of fans and db levels, I gueSs they could be powered right down as only a small (if hot) section. Not a big fan of the idea of having hole intakes on the floor as I think they could make bottle necks with stuff on top of them (sliding shelves etc) and I want my fans having an easy time and keeping their DBS low. Cheers Scrub!

 

[ScrubNinja]

No real worries with the two light fans as there is no pressure involved - plenty of quiet, high CFM fans around

I agree about the floor intakes. This was a quick thing I did up, the intakes are just symbolic of however you want to run things. Most of it is. The diagram even differs slightly from what I just described ...either way you will still get the same result - more headroom.

 

[Strangely]

No scrub-a-dub-dub thought dude?

 

[ScrubNinja]

Well personally, I'd make a filter like all my cabs have now. The carbon screen layer. Picture in the "exhaust room" a layer of screen or mesh about 1 to 2 inches below the exhaust fan, about the same level as the glass shield. Put carbon in and adjust thickness depending on stealth/cooling performance needed. Very easy to change carbon and very efficient. You would have approx 15cm x 30cm surface area which is probably up towards a commercial filter.

And lets not forget that because we've been so obsessively efficient all the way, our scrubbing needs are seriously minimal now. We only need a relative trickle flowing through that carbon to cool such an already cool cab, and to keep the smell from "falling out" the intakes. And because the air is moving slower, it's spending longer in the carbon, which is filtering it more efficiently, which means we can go minimal on the carbon depth, which means we can run a less powerful fan, which means the air will be moving slower through the carbon, which means..... and on and on. It's one big cycle of efficiency and you are holding the reins. Picture it, man. It's fantastic.

 

[Strangely]

It sounds good, I've seen alot of what you're talking about on the forums. I like things simple and neat, which I could probably still achieve using this method, but the main reason I was ruling it out was being able to pick up what I need in supermarkets with trips to hydro shops limited to occasional visits for ferts, rockwool cubes, carbon filters etc.

The big supermarkets over here, Tesco, ASDA (owned by Wallmart now) are NOWHERE near the size of your badboys and as such have far less of a range. And I've not seen anything put the tubular behemoth carbon filters you see me trying to squeeze in to my design on any of the UK hydro shops websites (which I'd visit in person).

Sod it I'm off for a quick drive to B&Q (DIY supermarket) to see if they have flat sheets or any other carbon based matting, cooker hood flat filters etc.

Last thing a bit off topic, how do you have a custom avatar? Edit Avatar doesn't seem to show a custom option, do you need 50 posts or something? Also I love yours along with ResinLungs and Cheesebuds, yours in particular was screaming out for an edit I couldn't get out of my head (I know, get out more). Anyway here it is, you don't have to use it or anything, I can just sleep soundly again!!

 

[ScrubNinja]

Ahahaha thank you bro, that's the funniest thing I've seen all day I had to stare at it a while to see. I must need to charge mah lazers!

About getting supplies and stuff, are you kidding mayn? Australia is a vacuum when it comes to anything cool. Electronics, grow equipment, choice in general... we don't have it. Want an S&P or Panasonic Whisper here? Good luck. And that goes right down the line for pretty much every grow product featured on here except maybe nutes and a couple things like that.

I would recommend against the carbon matting but you never know. If you go with it, consider using the carbon sheet as the screen, where my carbon filter would be. That way all you have to do is dump carbon in there if the matting doesn't work. The matting would be your screen/mesh. I can give you as many links as you want of people saying carbon mat doesn't work. A couple have said it does work so I would research closely which brands they used. But it's just a fact that it's never, ever, going to work as well as granulated activated carbon. The air in a carbon filter has to touch carbon before it can be cleansed of odour. Not sure how that is going to be achieved with something that is like 95% air. So there. An inefficient filtering media is the last thing you need.

Well, good luck man. Thanks again for the icon, that was some funny shit.