4X8 plywood grow box. 2K watts. venting? a/c? help!!!

Ok guys, help me out here. I have a 10X20 shed in my backyard that I want to put a few lights into. I am thinking of building a 4X8X8 box and putting 2 1K watt hoods in it. I chose 4X8 because it would be fairly easy to build with 8 full sheets of plywood. I could mount ballasts on the outside, and even cut a hole for an a/c if I need it. I am going to draw air from outside the shed and exhaust the spent air out the box into the shed. (Shed is not airtight by any means.) Thinking of doing a 400cfm inline fan through the 2 sealed hoods with a carbon filter on the way out of the box. I want to do this as simple as possible, so let me know what you guys think and anything I should take into consideration, Thanks!!

P.S. Where I live in the winter it is usually about 50-60 degress F outside So I will have plenty of cool air.

Sounds just like what I am doing.
Good luck.

i wouldnt put your carbon filter on your sealed hoods or you will still have smell issues, you want to exaust the room itself with the carbon filter and keep fresh air coming in. at least this is what i have gathered. otherwise your just filtering the clean air that your drawing through the sealed hoods....make sense?

the second set of fans and venting will also keep temps down in the box as 2k watt in a 4x8 is going to get hot even if your pulling semi cool air through, and you always want fresh air exchange on your plants for Co2 reasons, if you dont they will use up the Co2 in the room and not have any fresh stuff available, fresh air is always good for plants.

exaust from the top of the box (where the air is the hottest) and just use passive intake holes on the bottom of the box to allow cool air to come in, you want to be sure that your exaust is creating negative pressure so that any air leaks in the cab is taking in fresh air and any and all air coming out of the box is being filtered so that smell dosent escape.

good luck
RMTB

RetiredMatthebrute said:

i wouldnt put your carbon filter on your sealed hoods or you will still have smell issues, you want to exaust the room itself with the carbon filter and keep fresh air coming in. at least this is what i have gathered. otherwise your just filtering the clean air that your drawing through the sealed hoods....make sense?

the second set of fans and venting will also keep temps down in the box as 2k watt in a 4x8 is going to get hot even if your pulling semi cool air through, and you always want fresh air exchange on your plants for Co2 reasons, if you dont they will use up the Co2 in the room and not have any fresh stuff available, fresh air is always good for plants.

exaust from the top of the box (where the air is the hottest) and just use passive intake holes on the bottom of the box to allow cool air to come in, you want to be sure that your exaust is creating negative pressure so that any air leaks in the cab is taking in fresh air and any and all air coming out of the box is being filtered so that smell dosent escape.

good luck
RMTB

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Ok I think I catch your drift. One fan pulling outside air across the hoods and out the entire shed comepletely. Then a second fan at the top of the box sucking air through a filter into the shed? Seems I would need both fans to vent outside completley to keep heat from getting back in the passive intake ya?

Ok guys I have drawn up a diagram to get things rolling on this, let me know if this looks like it makes sense at all, I think I may need 2 fans or an a/c anyone??Sorry for the awful pic

HTP said:

Sounds just like what I am doing.
Good luck.

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i dont wanna make thebugslaaa paranoid but I think you guys r crazy for even thinking about growing in a shed. I wouldnt do it cause I would be worried about heat the shed is giving off. That would be a lot of heat, especially in the winter? If a helicopter with flir flys by and points the camera at the shed in the winter Im pretty sure that wouldnt be good. Wonder if they would follow thru with trying to get a warrent. probably depends on the police dept.

depends where you are... certain states require a warrant before they can even use FLIR. so... anything found with FLIR without a warrant, inadmissible in court.

i just hate when people automatically drop the same old mythical answer about FLIR and growing. yes.. it can be seen and yes it is always best to just make it as low profile as possible to save yourself from the troubles later, but it is far from true that if you are growing on PRIVATE PROPERTY (yours hopefully) and your grow leaves a rather significant heat signature, that the cops are going to come busting your door down over your "heat signature they saw come out of your shed on FLIR as they were doing random fly overs without warrants".

OP,
as for your question of will it work, i am doing exactly what you are describing and i can tell you what i have experienced and you can pull what useful bits of info you can out of my experiences. it sounds to me like your roughly close to the same area as I, as your temperatures during winter are consistent with mine, so this may be a bit more spot on for you than it will for others.

first i would suggest a closed system pulling air from outside.. through the lights.. and back outside of the grow area. with growing in the area you are wanting to, your going to be battling HUGE heat issues. you should invest in a portable a/c (hit craigslist.org... you can find them for about 150.00 used.) as your plants will thank you later. so far we have:
-closed loop light cooling
-portable a/c

depending on how many you are planning on growing at once, i have found that light movers are a LIFE SAVER! i run 1k lights (no idea what your planning on going with).

took a saw and cut hole in roof of shed... put one of those whirly bird vents on top of the shed.

now if your exhausting into the shed area to try to keep the noise down, passive intakes on the floor of the shed as well as that whirlybird on the top will be able to exchange air in that shed well enough to keep it cooler than if it wasnt vented. even though your running a portable a/c, i would still suggest a small (6") passive intake somewhere in the room. i see people on this site saying no no no it must be sealed and blah blah if you have an a/c, but that is a load of crap. i have insulated the walls, and ceiling of my shed with r-19 insulation and may recommend some sort of insulation for your box even if it is just the foam board stuff. it will help! with this set up, i run 2k in lighting with ballasts mounted near ceiling. passive intake hole as well as dual hose portable. carbon filter on ceiling with 250cfm can fan re-circulating air in the room. this thing is right out my back door and i never smell a thing unless i open the door.

First.. Check out Google Sketch up.. it can even make me look like I know how to draw.. lol

You're basically doing the old 4x8 plywood room thing a lot of people did before the 4x8 tent came out. Not that the tent is better for the plants but it's better for the room and easier to setup and tear down.

With that said you should copy what people do in 4x8 tents.

You're going to want to have several cool air intakes all around the box. If you just have one, you're just going to have one cool area and one hot area.

You can do it with one fan but you can do it better with two. one for the lights and one for fresh air. If you dedicate one fan to the lights you can take cold air and pass it through the lights and out with out the need for filtration that slows the air flow. Then have a temp control attached to a fan that is draws through a carbon filter. This fan only turns on once the set temp is reached. The fan on the lights stay on as long as the lights are on.

This will come in handy when you add co2. It will allow the co2 to stay in the room and not get blown out the lights.

You can do it with one and be fine. But later you'll want to go to two if you want to use co2.

bde0001 said:

i dont wanna make thebugslaaa paranoid but I think you guys r crazy for even thinking about growing in a shed. I wouldnt do it cause I would be worried about heat the shed is giving off. That would be a lot of heat, especially in the winter? If a helicopter with flir flys by and points the camera at the shed in the winter Im pretty sure that wouldnt be good. Wonder if they would follow thru with trying to get a warrent. probably depends on the police dept.

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you must not live in Cali haha. I have no problem with law enforcement. I am 100% legal and I will only be running 2 lights, that is child's play here. I will most likely call the sheriff and notify them of my grow before I put any plants in there. That is what I did with my outdoor last year and they gave me the OK in writing. (gotta love cali)

eDude said:

First.. Check out Google Sketch up.. it can even make me look like I know how to draw.. lol

You're basically doing the old 4x8 plywood room thing a lot of people did before the 4x8 tent came out. Not that the tent is better for the plants but it's better for the room and easier to setup and tear down.

With that said you should copy what people do in 4x8 tents.

You're going to want to have several cool air intakes all around the box. If you just have one, you're just going to have one cool area and one hot area.

You can do it with one fan but you can do it better with two. one for the lights and one for fresh air. If you dedicate one fan to the lights you can take cold air and pass it through the lights and out with out the need for filtration that slows the air flow. Then have a temp control attached to a fan that is draws through a carbon filter. This fan only turns on once the set temp is reached. The fan on the lights stay on as long as the lights are on.

This will come in handy when you add co2. It will allow the co2 to stay in the room and not get blown out the lights.

You can do it with one and be fine. But later you'll want to go to two if you want to use co2.

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This makes sense if I was running c02, but I will not be, So I need fresh co2 coming in through a non-sealed passive intake I believe? Sealed room with no c02 would not allow the plants to breathe.

bde0001 said:

i dont wanna make thebugslaaa paranoid but I think you guys r crazy for even thinking about growing in a shed. I wouldnt do it cause I would be worried about heat the shed is giving off. That would be a lot of heat, especially in the winter? If a helicopter with flir flys by and points the camera at the shed in the winter Im pretty sure that wouldnt be good. Wonder if they would follow thru with trying to get a warrent. probably depends on the police dept.

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DUDE! Screw IR, The roof of the shed will be a dead give away alone to the neighborhood when it's the only thing in town with no snow on it if it snows by him/her! 2k watts will be a sauna. Not to mention if the shed isn't insulated your going to here a a/c running all day and night.

you killed all those stick people in you diagram. bad boy. i dont think you have an idea about how much heat those lights will still put into the room even with air cooling. oven temps.

The claims that it will be overly hot are only partially true. I did have a heat issue when I first begun, but insulation on the walls and ceiling fixed that. Its over 100a outside and my room peaks at 78 degrees mid day with all equip on and a portable a/c. Its completely possible, but if in a shed, here is no half assing this setup.

My 2 cents,...
If you're legal, and will even have the cops blessing for goodness sakes. Why restrict yourself to a box? A box in a box at that. Grow in the whole shed, i guarantee it isn't long till you want to expand. Hell put a damn clear roof on the shed too, so you can get sunlight, it doesn't even cost 2 cents.

As for winters and snow;if the heat is hot enough it may start making a fog with the snow on top of the shed as it evaporates.As long as can keep the temps down then it will not be alarming,but every time the shed opens it will breath that hot air out. Do sheds have chimneys? i wouldn't think so.

It's a nice setup this was my original plan when i first began growing years ago but,i never stuck with it i went with closets.

That looks like almost the exact set up I have in my veg room and have had no issues with it. However, my finishing room has 4000watts. In that room I have 2 fans. 1 cools the lights the other has a filter for air exchange. Looks to me like you are on the right track. When I set my rooms up I ran them for a couple of days to monitor temps before any plants were in there.