I've just completed one grow in a 1.2m * 1.8m closet, its 3m high too.
I had to keep the door open, and with just a dinky little fan blowing on them from the doorway, they managed to stay at about 27C all the way, under a 400w HPS.

For this grow, I decided to do things a little better.
I smacked out a 12 cm round exhaust hole at about eye level and a 10cm intake at roughly floor level. I inserted the 12cm flex ducting, pulled it all straight and inserted it into my brand new fan which I've set up with a cooltube around my 250HPS.
This is supposed to be my prototype for my bigger lamp which I want to add in a few weeks, once it too has become a cooltube.

I bought a 100 dollar ductfan, 350m3, which was pretty much the biggest fuuck I could get hold of:

TD 350/125 (125mm/360m3/hour) - Hydroponics UK, Hydroponics Systems & Grow Lights

then I connected it all up, turned it on, and stepped back in anticipation.
33 fuuking Centigrade with the door closed, after 20 mins.
about 29C with the door open.

So this whacking great fan which sounds like a monsoon, and is inserted into a cooltube is doing a much worse job at sucking out heat, than my old 20 dollar fan was at blowing in cool air.
What am I doing wrong?
It's driving me nuts.
Also, I have 7 babies that desperately need to get in there quickly.

Things that are confusing me:

The cooltube glass is cool but the air around it is fairly warm. Since the exhaust tube from the cooltube goes to the exhaust opening in the closet wall, how is other ambient air in the room supposed to exit? Do people have double exhaust holes in two walls opposite or something? One for the cooltube, and one general ambient air exhaust?

The fan seems to blow like crazy, but theres not much sucking going on apparently. Wouldnt it be better to reverse the cooltube, and have the fan stormblowing the air across the bulb, through the cooltube, into the flex ducting and out, rather than trying to suck it out?

The exhaust hole is on the same wall as the intake hole. I know thats not recommended, but I had little choice, though I could perhaps make a hole on the other side, with some difficulty. I would think this does not matter much since I'm leading the exhaust air through ducting.

Any help would be amazingly appreciated, I've been grazing my knuckles banging holes and wracking my bleeding brains for 3 days now.

*Rolls a depressed spliff*
faithlessxxx Reviewed by faithlessxxx on . AAAARRGGHH!!! I DONT UNDERSTAND! I've just completed one grow in a 1.2m * 1.8m closet, its 3m high too. I had to keep the door open, and with just a dinky little fan blowing on them from the doorway, they managed to stay at about 27C all the way, under a 400w HPS. For this grow, I decided to do things a little better. I smacked out a 12 cm round exhaust hole at about eye level and a 10cm intake at roughly floor level. I inserted the 12cm flex ducting, pulled it all straight and inserted it into my brand new fan which I've Rating: 5