Temp problems

[Ganjahero]

I have a box thats 31"wx16"dx34"h. I have a 250HPS in an air cooled hood w/ glass with a 105cfm fan pulling the air out and a computer fan attached to the other opening of the hood blowing air from the box into the hood. I have two 2" PVC air intakes.

Im not using the HPS right now but even with just a few CFLs the temps get far too high. As high as 90 with the fans full blast. Im getting good suction from the intakes, enough to hold up a piece of paper. The room temp is usually 70-74. Are my temps too high because I need more air intakes? Is 105cfm not enough? Any help would be awesome, thanks!

 

[FreezerBoy]

I use a 76 cfm on my 250CMH in a 22"x29"x54" cab. 105 CFM is more than enough, but with only two 2" intakes, you're choking the fan. How big is the exhaust? Double that for intake. Some here have gone as far as 4x the exhaust.

 

[maxima32]

i dont understand what fan are you using to blow air out and what are you using for fresh air inside the box

 

[Ganjahero]

Im using the 4inch 105cfm fan to blow the air out. Its a passive intake, there is no fan pulling air in. I guess I will try to add another two inch intake. Maybe even two.

 

[maxima32]

try that because if you have such a great temp out the box than you should definately be trying to get this air inside of it. Plus the box is probably small compared to the room its in so you shouldnt have a problem cooling that area off.Make sure out take is at top and intake is at bottom. Let me know how this works for you .

 

[FreezerBoy]

I could cool my 150 HPS with a 4" fan with single 4" intake. The 250 CMH turned the cab into an easy bake oven. The addition of a second 4" intake brought things back under control.

 

[Ganjahero]

Alright, thanks for the advice, im going to get more PVC today to make two more inlets. I'll hopefully have them in by tonight and i'll let you know how it goes. Thanks again.

 

[Ganjahero]

I added two more 2" intakes. My temps are still not going down. I dont understand what the problem is. If anyone else can give more insight id appreciate it a lot.

 

[Maculele]

Where is the hot air going that comes out of the cab? If it's going back into the room, I'd assume that part of you problem is that some of that same air is going back into the cab which defeats the purpose of course. What's the total area of intake that you're working with? That amount of air movement sounds good enough to me. I've seen worse and the temps were more reasonable. Also, is 90 really that high? I think the girls could probably bear that, but they'd do better with something in the lower 80s, esp. if you aren't using CO2. Good luck, pal

 

[hoosierdaddy]

A 4" opening is 12.56 sq inches area.

A 2" opening is 3.14 sq inches.

An intake that is double the size of the exhaust is going to give you your best scenario for success.
Double the 4" opening is 25.12 sq inches.
25.12 / 3.14 = 8
You need to have eight 2" openings to equal double the 4" exhaust.