fan/ventilation question

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Originally Posted by Rusty Trichome

Do you have the lights already? If not, get one, and try the sucker out. This will give you a good idea on what you can and can't do from there. Otherwise it's just speculation.

7 x 7 is a very small room for two 600w lights, and they would likely need the heat exhausted aggressively. (unless you live in Alaska or Siberia)

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What would be the proper way to hook them up?

Open Hood 600W > Ducting > 600W Hood > Inline Fan > Ducting > Inline Fan > Scrubber ?

if you run 2 HPS's and want a single exhaust, don't connect them in-line, use a Y-adapter on your ducting to connect them in parallel. this will allow cooler air to enter both, instead of cool air enter one and hot air entering the next and extremely hot air coming out the exhaust end.

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Originally Posted by syde00

if you run 2 HPS's and want a single exhaust, don't connect them in-line, use a Y-adapter on your ducting to connect them in parallel. this will allow cooler air to enter both, instead of cool air enter one and hot air entering the next and extremely hot air coming out the exhaust end.

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Y adapters on both ends?

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cool air ---- HPS Hood -----\
                            \
                              -------Inline fan ------ filter --- hot exhaust
                            /
cool air ---- HPS Hood -----/

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edit: actually, i don;t really know what the filter hookups are like... it would be best to have the fan after the filter if possible... easier to pull air through things than it is to push


another edit: i sould also say, that it is imperative that the length and diameter of the ducting between the HPS hoods and the Y-adapter be exactly the same, or as close to the same as possible on both sides of the Y.

Otherwise the fan will favor one of the hoods and pull more through whichever one is easier for it and the other hood will suffer slightly.

props....Is it better to have the filter attached to the hood setup or should I just run it as its own setup?

Dont know where to start on this one. First off, 7x7 with 2 600s is not that much light for that space. I run 2 1000watt lights in a 4x8. I agree the Y is a good idea, but it sounds complicated. Speaking from my personal experience, in my opinion its not necessary. Use reflectors with 8 inch ducting and get a good 8 inch fan, you will be very happy with that setup. You can get away with 6 inch and save a little money, but come on, if your going to do it, do it right. Unless your drawing air from inside your growroom and blowing it through your lights you dont need a carbon filter on the end. Think about it, non smelly air from outside your growspace doesnt become smelly while running through a seeled light. Your carbon filter goes on the end of your other fan that is venting your room. You need to exchange the air in your room every 3 to 4 minutes. No offense to rusty, but he is a little old school when it comes to growing. Also, i would reccomend the good sealed hoods, with rubber gaskets and all that good stuff. I got the cheep ones, like a whole 10 dollers cheaper, and they whistle. Its annoying.

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Originally Posted by canadagrown

How do you guys go about light proofing the passive intake holes?

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Turn an elbow looking down on the inside of the room and the same outside.. paint the inside of the them with black spray paint..

Ga Grown!

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Originally Posted by GaGrown

Turn an elbow looking down on the inside of the room and the same outside.. paint the inside of the them with black spray paint..

Ga Grown!

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or, use black plastic 'sewer pipe' elbows, from the hardware store ... I only use one, either inside or out, doesn't leak enough light to affect my plants ... :smokin:

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Originally Posted by the image reaper

or, use black plastic 'sewer pipe' elbows, from the hardware store ... I only use one, either inside or out, doesn't leak enough light to affect my plants ... :smokin:

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You could buy a bag of HVAC flex with the insulation on it too... It can be used in many applications. This would be the type used for your central heating and cooling.


Ga Grown!

ok so you have been given a lot of advice and i my self run 2 600's, in a 5x10 room.with a 7x7 room do not hook up a charcol filter at the end of your lights,this will slow down 2 things, the air exhausting the room and the heat evacuating the lights. use a seperate fan doesnt have to be huge or expensive to solely run the lights.find a wall cut a hole through it. 600 to ducting to your other 600 and out another hole out of the room.if you use only any exhaust fan it needs to be twice as big as it would be if you were yousing an intake fan, this is because you are using that fan to now do 2 jobs.your room absolutley must be 100%air tight in order for a passive system to work.the only air coming in will be through your pre cut intake holes...you could try the other suggestions,but i have tried them all and i live i a verry cool environment and am still having mild heat issues.. personally its just easier to use 2 or 3 fans. i use 4. to small intakes @145 cfm a piece one exhaust 445 cfm with a charcol filter and a 245 cfm for my lights.all 4 fans have differnet uses. soooo, in short if you do the passive u must vent the lights with the own dedicated fan of reap the heat issues, find an 8 inch of 12 inch fan for your filter and exhust. i hope you find the bet method with out having to spend a bunch of money,best of luck.