Cab advice.

[fly poster]

ok I have a full sized drobe I am gonna convert. 6ft/3ft/2& half ft.

Using 400w Hps, what extractor fan size should I go for?

I am in the UK if it makes any difference to makes and ranges.

Thanks.

 

[messn'n'gommin']

These are in units of cubic feet per minute and I offer my apologies for not in being able to translate into cubic meters per hour, but, this is a good rule of thumb to go by.



btw...go a bit bigger if you can. The extra margin of error can come in handy.

If stealth is a concern or even a measure of control, you might to want consider hooking it up to a variable ac transformer.

hth...Good luck!

 

[Iron Lungs]

hope everything works out man! i had to put alot of thought in my cab! But worth it in the end

 

[Iron Lungs]

BTW if you need any help just let me know!

 

[HybridVigor]

All depends on your inlet. Are you going to have another fan pushing fresh air in? If not get a fan quite a bit bigger, create a negative pressure so it sux in new air from the inlet. Dont stress too much about the fan size, you would need a massive helicopter fan before it was bad, air flow is important rather go bigger

 

[geopolitical]

I would go with a minimum of a 125mm centrifugal but a 150mm would be better, assuming you'll be running carbon. The bigger your intake, the fewer twists and turns, the better insulated & separated your ballast and fan are from the main cabinet area, the less fan you'll need.

 

[pinecone]

A someone with a 400w light in a similarly sized cab I will tell you that you are going to need to be concerned about heat. My recommendations
* locate the cab in cool room and remotely locate the ballast so that it isn't heating up the air that comes into the cab. Vent the air to another area of possible.
* you need lots of intake area - at least 1 8"x8" darkroom vent
* you can never have too much fan - I'm running a 6" Vortex rated at 400+cm. I might be able to get away with the 4" model, but any sort of squirrel cage blower would be insufficient.

Good luck

Pine

 

[geopolitical]

I have a 400w cabinet with a cabinet about that size with carbon filter all running on surplus 120mm 12v fans undervolted to 5v (and silent as a result).

ALWAYS ACTIVE EXHAUST. A cabinet kept at a slight negative pressure won't leak smell out of any gaps between door & weatherstripping. Putting your fan on the exhaust also means you can put your carbon/dust filter in front of it which increases it's lifespan. But of course the additional heat load is going to reduce it's lifespan so, win some lose some.

Also, if you have a potential cool air source exploit it. Many houses in my area have access panels to the crawlspace in several areas of the house. On hot days intake air from my crawlspace can be nearly 15 degrees cooler than the house as a whole. Intakes should be near the floor if possible to take advantage of natural thermal gradients.

Remote your ballast and INSULATE ductwork if at all possible. Seal your air leaks. Even tiny ones. Use metal tape or duct mastic (mastic is better but relatively permanent, not good for cleaning purposes). Time your cabinet to turn on during the coolest time of te day, and turn off during the hottest hours of your house (which may differ than the hottest hours outside).

Air cool your lamp. If using a reflector insulate the surfaces that will radiate heat into the cabinet with a thermal blanket (be sure your insulation is heat rated). For just about any given fan larger ductwork with fewer turns will result in greater airflow.

Compartmentalize your growbox. Two small fans may be able to quietly cool your cab if you have separate intakes & exhausts for both your lamp & cabinet. The air cooling the lamp will not have picked up ambient heat from the cabinet and the air cooling the cabinet will not have to also pull heat from the lamp.

Don't eat hash before posting. . . lemmie tell you this has been an experience.

Also, min/max thermometers and hygrometers are INVALUABLE for finding out what your growbox looks like 24/7 and can tip you off to problems.

 

[fly poster]

Thanks, everyone. Invaluable advice, and thanks Ironlung, for the offer of further help. I will definately be in touch. I have bought a fan,(175m3/hour) , but can only afford the one for now, I just hope it don't get too hot! (I am on the third floor in a building and it's summer) I'll be posting pics soon.

Thanks again all.

 

[fly poster]

The more I think about it, and the more I read on here, heat is gonna be an issue for me. I think I have worked out a solution. I am gonna buy a cheap fan (hardware store near me sells bathroom fans for £10). about the height of the light, i'll make a vent and bring in cool air with the bathroom fan, using my bigger more powerfull fan for extraction. The cab is right next to my window, and the window is where the vent for the bathroom fan will be, so if I time it so my light is on predominately at night when it's cooler, I should be able to get a decent temperature.

Waddya think?

 

[smokeymacpot]

The more I think about it, and the more I read on here, heat is gonna be an issue for me. I think I have worked out a solution. I am gonna buy a cheap fan (hardware store near me sells bathroom fans for £10). about the height of the light, i'll make a vent and bring in cool air with the bathroom fan, using my bigger more powerfull fan for extraction. The cab is right next to my window, and the window is where the vent for the bathroom fan will be, so if I time it so my light is on predominately at night when it's cooler, I should be able to get a decent temperature.

Waddya think?

i think your thinking along the right lines