Dollars per degree?

I'll keep it short and simple: 2'wx2'dx4'h box, 6 30W CFLs

Stealth is a very important part of this op, so keeping noise down is key. I'm trying to stick with all "silent" fans.

I originally had two of these (http://www.newegg.com/Product/Product.aspx?Item=N82E16835103024&nm_mc=TEMC-RMA-Approvel&cm_mmc=TEMC-RMA-Approvel-_-Content-_-text-_-) running as exhaust venting air out the top. The box was running hotter than ideal, around 90°

So I added this beast (http://www.newegg.com/Product/Product.aspx?Item=N82E16835705061&nm_mc=TEMC-RMA-Approvel&cm_mmc=TEMC-RMA-Approvel-_-Content-_-text-_-) as an intake fan blowing up from the bottom. Suprisingly it really didn't make much difference, current temp is 88° and higher than I want it to be

The question is; keep investing more money trying to cool the box, or let it be? At what point is it no longer worth the investment?

you exhaust fans are not powerful enough. try switching your input fan. you shouldn't really need an input fan although it doesn't hurt to use one.

and yes, you do need to get the temps down, ideally to the mid 70's.

I didnt know CFLs put off that much heat. You've got me worried now, My box is 2x2x3 and I just ordered 8 CFLs. I hope I find some way to cool it down...

You need a negative static pressure. You switched your system from one which had that, to a system with an active intake which is blowing in more air than it can suck out. That 320 moves 127 cfm, while those 120 mm fans combined only move about 88 cfm's.

What you should do is take that 320 mm fan and use that as your exhaust. Find something else to do with those 120 mm fans. Maybe use them to circulate air inside your box. Passive intake on the bottom, active exhaust at the top equals negative static pressure which keeps temps cool and smell in check.

I appreciate the reply. Because of the way that they box is constructed the fans fit really well where they are, so I ordered two more 120mm fans to replace the ones I have. The CFM rating is doubled so I should have 127 CFM coming into the box and about 170 going out. Of course I'm sacrificing some of the stealthiness because the new fans have a higher dB rating but the box is literally silent right now so it should be fine.

Thank again johnny.

Build a new box so you can use the big fan as exhaust, even doubling the cfm of the 120mm fans you have now is not going to cut it. Your flaw is your box not your fans, that's what you need to redesign or replace.

This guy did a grow exactly like you describe with the same number of cfl's and you can look up his name on icmag and find that grow, see how his box is set up with the exhaust, he has less fans than you did originally:
http://www.icmag.com/ic/showthread.php?t=88449&page=1&pp=15&userid=30088

So you're saying having less CFM leaving the box will somehow be a better idea?

* and a correction to my last post, the new fans are 89.xxCFM each so around 180 total. This is somehow less effective than having one big fan pushing 127?

Get a real fan, a cool tube and a muffle box....

DIY...Noise Controll....Canfan/squirrelfan....SOUND BOX

I run a 600 watt HPS in a 36x20x54 tent with NO HEAT ISSUES...

My sig has some more useful links...

Set it all up like this...

dingleboy said:

So you're saying having less CFM leaving the box will somehow be a better idea?

* and a correction to my last post, the new fans are 89.xxCFM each so around 180 total. This is somehow less effective than having one big fan pushing 127?

Click to expand...

No I'm saying there is probably a flaw with your box design.
Your exhaust is poorly located or something, I don't know, I haven't seen your setup. Never did I say less fans is better, I did say you should have fixed or replaced the box it sounds like there's something wrong with the design that is causing poor performance.

Give us pictures...