Cooling a shed, better to pull or push

I am in a pretty hot climate and this is going to be my first spring and summer growing. My setup is an 8' wide, 4' back and 4' tall. It is enclosed in plywood and is pretty well self contained with the mylar inside it. The shed is 8 feet wide, 12 feet front to back and about 9 feet tall with one, 3'x5' window. I have my HPS setup to run overnight instead of during the day but I still have heat issues.

Right now I have taken two 50 cfm exhaust fans and rigged them up to ducts and on the outside of the shed I have leaned a piece of plywood over the window (looks trashy but I need that window blocked so people don't wonder why I have ducts coming out of it.

My grow area is split into a 12/12 side and a 24 hour side, right now the 12/12 side is the only one with a fan and it doesn't do much. This morning I went out there and set the an exhaust fan in my flowering room (by far the hottest) and put it to "pull" air from the shed in. Then I set my "push" fan inside my veg room sucking air out and out the window.

I also have a larger exhaust fan (I think it is in the 100-200 cfm range). What I am thinking about doing before work is to take that larger fan, mounting it in the highest point in the shed I can and then ducting it outside in a "pull" fashion. Since heat is going to naturally rise (and tends to build in an attic like that) I figure not only will that suck the hot air out, but I could use the other 2 fans inside the grow rooms to suck fresh air from the outside.

The big problem here is that is going to cool the room by maybe 5 to 10 degrees, which is fine now but now when I am pushing triple digits. I know a window A/C unit will be my only option for those days but I just wanted to get some general air movement advice.

Nice set up man, that'd be my area of choice, just make sure it cant be tracked(from the sky) by the heat it produces. With this unstable weather im having the same heat issue as you. im only seeing 90' as the hottest but its still probably stunting flowering growth. Tried picking up a small air conditioner but the window unit was the smallest i could get locally, so im going to have to get one online. I was thinkin opening my intake hole in my box will allow for more air movement(its passive). But Matthew, id say your right on track, id just add more fans within and have that strong cfm fan pulling air from your light and room out for exhaust. You could put a 200-300 cfm in depending on the size of your light and then attach a carbon filter to it, having your main fan as the center peice of your system.

You could also set your room to passive intake air so your set up isnt depending on the air coming in, so then you could have your window ac unit in replace passive intake. i I have my set up as my fan blowing through my light enclosure, and its working out fine, just need to fine tune it to keep my temps cool. But yea im doing the dark during the day and light during the night but its not as effective because my box isnt as efficent as it needs to be. But we'll get it, its all research and trail and error

swishatwista said:

Nice set up man, that'd be my area of choice, just make sure it cant be tracked(from the sky) by the heat it produces. With this unstable weather im having the same heat issue as you. im only seeing 90' as the hottest but its still probably stunting flowering growth. Tried picking up a small air conditioner but the window unit was the smallest i could get locally, so im going to have to get one online. I was thinkin opening my intake hole in my box will allow for more air movement(its passive). But Matthew, id say your right on track, id just add more fans within and have that strong cfm fan pulling air from your light and room out for exhaust. You could put a 200-300 cfm in depending on the size of your light and then attach a carbon filter to it, having your main fan as the center peice of your system.

You could also set your room to passive intake air so your set up isnt depending on the air coming in, so then you could have your window ac unit in replace passive intake. i I have my set up as my fan blowing through my light enclosure, and its working out fine, just need to fine tune it to keep my temps cool. But yea im doing the dark during the day and light during the night but its not as effective because my box isnt as efficent as it needs to be. But we'll get it, its all research and trail and error

Click to expand...

That is another thing, my HPS is an all in one ballast, bulb and reflector all in one. I have it hung as high up as I can get it so my plants have about 3' from the ground to the bottom of the light. So I am going to trim so that I have lollypops tonight.

I am going to cut some soffit holes I think and have the air exhaust and intake one different sides.

FLIR would spot me pretty easy right now but that is not enough for a warrant in the US. They would need more and no one knows about my grow and there is no smell. In the future I plan on getting some of the IR blocker and coating the whole place with it.

Why not just buy a window ac unit? A 5ooo btu a/c will cool a 10x10 with average houshold settings. So a 5000btu setup will cool that space perfect with the lights in there. I bought my on craigslist for 50dollars... Why would you not go that route, its the cheapest/bst way to go

im having the same prob in my grow room i was wondering if those portable evaprotive coolers will work in the room if you have it duct with fresh air!!!!!!if it does could this be a solution for us????

pull baby always pull!!!

Well I went to a discount electronics store in my area and they had 5000 BTU window unit for $69.99 brand new (some crap brand though). I think I am going to go back, grab that, then use my two 50 cfm fans as filters.