CFL heat question

Hi all. I'm working out the details for a rubbermaid grow setup that is going to be 7.39 sq. feet. It's going to have 2 passive intake holes about 1 1/2 inches wide on one side, and 2 computer fans hooked up on the other side for active exhaust. I want to put 8 40 watt CFL's in it for a total of 21200 lumens.

My question is, am I going to have a major heat problem with this much lighting and this small of an exhaust? I don't want it to get over 85 degrees and I would prefer not to burn down my house. The room I will have it in is going to be pretty cool during winter - around 55-60 degrees F. If I am going to have a problem, should I go with fewer lights or a better exhaust?

Yuh Its gonna be a little WARM...
-Swisha

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Originally Posted by SwishaSweetz4Me

Yuh Its gonna be a little WARM...

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Warm as in my plants won't grow or warm as in I'll be calling the fire department?

Instead of computer fans, would it work if I installed a couple of regular fans at the top with passive intakes at the bottom?

This will be my first grow so I don't really know what to expect as far as temperatures.

Lol not enough for the fire department. You should be good with sum exhaust at the top and equivalent passive intake. You should be straight
-Swisha

i made a 20 gallon rubbermaid box with 6 23 watt cfl and had one 90 cfm computer fan on the top and had 2 passive intakes on the bottom on either side and it was ok if the house stayed at or below 80 degrees, anything above it got a little hot in there. so you might want to put 2 fans on it and make sure you have some vent holes the same size as the fans, or more smaller holes.

I've only used CFL's, heat-issues being the reason. The funny thing is, everything I read would say that CFL's are cool running (not much heat), BUT in my experience, they must be referring to just running one or two because when I was running nine 23w CFL's, it would get blazing hot (not fires though! not quite THAT hot).

But I think you've got it under control with the intake and exaust, so it should work well for you.

I'm running sixteen 23 watt (100 watt equiv) CFL's right now, and there's no way I could run those without some good ventilation!

As hot as they get, it makes me wonder exactly how much more heat you would get from MH and HPS lighting.

Anyways, good luck with that!

Chad

PS: It takes a little while for the CFL's to warm up before it starts getting hot, so before you get started growing, go ahead and see what kind of temps you'll be dealing with beforehand. This will give you an idea of whether you need to add a higher cfm fan or better intake, etc....

i always hear heat issues about 5 + 20-40w cfl's. but what about 1x 250w cfl? in a 0.6mx0.6mx1.2m tent, with a desk fan aimed at top of plants, and a few computer fans for vent. air intake is there of course. any idea's?

i used 3 23 watt cfls and 3 42 watt and i used one computer fan and had no heat problems except for when the plants touched the lights they would get burned. Might have something to do with the room that the growbox is in was quite cold and i had a fan blowing cold air from outside towards the growbox. i dont think you should have heat problems if you use 2 computer fans, assuming you are not using the little tiny ones you hook up to a 9 v battery

now that i read it will be 55 - 60 f in your room you will be just fine i am 99% sure

oh wow thanks, 55 - 60 thats a temp that im looking for anyway so it should be ok. erm i had this vent system which had a carbon filter but was too loud, i havnt yet set up the pc fans. when u say not small pc fans could you be more precise and point me in the right direction. i will use 3 or 4 if needed. they dont make a lot of noise do they? thanks

As for computer fans, you can get them up to 360mm in size, but the most popular of the larger fans is 120mm (popular among computer users, that is). And I must say wow! I just looked at the CFM ratings on these 120mm computer fans; I never realized the CFM's were so good. One 120mm computer fan, rated at 133.60 CFM. I never would have thought they'd pull that much air.

Either way, here's a link to that fan:
Newegg.com - Scythe DFS123812-3000 "ULTRA KAZE" 120 x 38 mm Case Fan - Case Fans
(if the link doesn't work, go to NewEgg and search for DFS123812-3000)

Anybody heard of running a small carbon scrubber with these small fans?

wow thanks im from uk but now i know what im looking for wow them things can push a carbon filter wow wow wow wow stealth stealth

For about $35 you can get a 4" in-line duct fan (go to any evil big box store (lowes, home depot, ...) and check out the hvac department) which will push nicely through a passive exhaust with a carbon filter, and its a perfect size for a rubbermaid box.

Hey Chadsvb,
Im running a 120mm computer fan at 9V,not sure of the CFM...but I have 2 home made carbon scrubbers attached to it,both intake and exhaust side of it. It seems to work fine and still does the necessary venting.

I have only about 3 23Watt bulbs in about 8 ft sq space and the vent is only 20mins every hour. I also have an oscillating fan made from a pusher prop for an rc aeroplane and a mini motor. My temps stay around 80f, which is maybe a bit hot compared to optimal but growing fine.

Good luck drewdp, dont sweat it too much, in my limited experience this stuff grows easily.Peace

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Originally Posted by DrewPD

Hi all. I'm working out the details for a rubbermaid grow setup that is going to be 7.39 sq. feet. It's going to have 2 passive intake holes about 1 1/2 inches wide on one side, and 2 computer fans hooked up on the other side for active exhaust. I want to put 8 40 watt CFL's in it for a total of 21200 lumens.

My question is, am I going to have a major heat problem with this much lighting and this small of an exhaust? I don't want it to get over 85 degrees and I would prefer not to burn down my house. The room I will have it in is going to be pretty cool during winter - around 55-60 degrees F. If I am going to have a problem, should I go with fewer lights or a better exhaust?

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dunno.... my cab is a 6 ft triangle thats 8ft high, has 10 23watt CFLs and and 10 4ft 2 tube T-12 flouro fixtures in it. the room temp runs between 70 and 75, the tops of the plant run around 80. The top of the cab is open and I have a 16 inch box fan blowing in from the bottom of the cab. I have been getting great results.