Problem with the heat...

Hi everyone..

So I have this problem with the heat at the canopy level. I bought myself a nice 250cfm fan and a cooltube, and while everything is set up and running, my 250watter still produced too much heat. It's about 30C/86F at canopy level.

I've honestly searched far and wide about cooltube setups and I've been stretched thin from it...

The fan itself is new, I just got it today after upgrading from a poxy 60cfm. I hooked up the old fan to the cooltube, but it had to be paired with an oscillating fan to keep the temps at 30C.
I'm desperately trying to eliminate the need for an oscillating fan, as my cab is small as it is (about 1,9x1,6x5,2feet).

As of now I'm pulling the air from the cooltube and exhausting it oustide. I have seen setups were the cooltube is on it's own independant ducting system, although I have also seen people do what I do, I swear I thought my calculations were all right and that 250cfm would be enough.

I'll add a few pictures to get you guys a good idea on how the setup looks like.

Peace, and thank you for your time.

I've been thinking about maybe adding some more intake holes? I don't know if that would help with anything though.

The air itself in the whole room is cool, definitely lower than 78F. I open the door to the garden and let the coldish air flow in everyday.

Can anyone with a cooltube asses that if I were to push the air over the bulb that would be a better option? I swear I only feel the need to keep the temps at 27C/80F, I'll be content then.

Maybe I could use the older, weaker fan and stick it in one of the intake ports to create an active intake? Seems that people are against this type of intake, so I don't know.

where does the air exhaust to? it looks like you're just blowing the hot air into the room around the box which it just sucks back into the tent effectively just moving warm air around. the hot air needs to leave the room

Hmm... the air is exhausted into the room, no ducting what so ever. I don't think it's a possibility for me to somehow allow the air to constantly leave the room, but maybe I could just move the exhausted air furthur away from the grow box? Thanks Crocodile, I'll try it out now.

Not much happened, I'm wondering if a new intake hole would suffice. Apparently the general consensus is that with a passive system, the intakes should be 2-4x larger than the exhaust... If I figure out some way to drill a new 15cm hole, that might do the trick.

it's not going to do anything because the intake is just taking in exhausted air

I mean I'm now exhausting air to the other side of the room, so it's not being activly taken in by the intakes. Maybe I'll just have to go with an active intake.

Gregor Eisenhorn said:

I mean I'm now exhausting air to the other side of the room, so it's not being activly taken in by the intakes. Maybe I'll just have to go with an active intake.

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it's all the same room and air supply bro. your air is not exchanging at all. you have turned your light into a space heater

im running 4k in a bedroom right now I have to shut the fans off periodically to keep the room warm enough. the hot air has to leave the room and any area you pull air from

There is an old vent on the other side of the room... maybe if I move the whole box there I might be able to get some ducting to point the exhausted air into the hole... I'll try it out, but you're completely right about the air exchange.

CrocodileStunter said:

im running 4k in a bedroom right now I have to shut the fans off periodically to keep the room warm enough. the hot air has to leave the room and any area you pull air from

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I'd love to do that one day. no problems with high heat.

I always clip a 4 or 6 Inch fan next to my cool tube and have it blowing right on the tube. Helps me by about 5-10 degrees at the canopy

Mylar said:

I always clip a 4 or 6 Inch fan next to my cool tube and have it blowing right on the tube. Helps me by about 5-10 degrees at the canopy

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Yeah, fans really do help with that heat generating under the lamp, I just order a small usb one that's about 12cm in height, so I'm sure it won't take up too much space.

I was just so sure that with a 250cfm fan the heat from the bulb would be exhausted and no hotspots would be made.

I'm just wondering what size fans people use when they don't have any other additional fans and a passive intake.

Last thing I could try is buy a new temperature gauge, I think it may be off.

The funny thing is that under the light when I put my hand over the canopy it doesn't even feel warm! So I don't get it, what should I trust, the hang method or the temp meter?

Trust your plants, they'll tell you. And the hand thing works too. My in line fan on my 600w does 345cfms with the additional clip on fan my room is 80 at the hottest 77 on average.

You're right, the leaves don't curl up and the growth rate is amazing (best I ever had, I love DWC).

Maybe I was just expecting too much with the cooltube and the fan. But when I think about it, without the cooltube I could only manage to keep my 250 watter 40cm from the canopy and that was pushing it, now I lowered it to about 18cm and with that small PC fan blowing in between the tube and canopy the temps are 27C, so I'd say it's doing amazingly.

Nice brother. Enjoy!

Cheers, good luck with your grow as well!