Hey Grasscity, long time, no talk! I finally moved up from closet growing and have a bit more space on my hands. So, I currently have a large basement I'm sectioning off for a perpetual grow. Here's a generic outline of what the flowering chamber will be: Lighting: Using 6-600W lights, two rows of three, air cooled yield master II hoods. My plan is to use one inline fan to air cool all 6 hoods. Using a y-splitter, and then daisy-chaining the lights together. Air will be pulled/pushed from outside the environment, and only be used for cooling the lights in this application, air will not come from the flower chamber, or go into the flower chamber for this light. Ventilation/smell control will be covered by another fan. My questions are, how big of a fan am I going to need to push this much air. They will need to travel about 12 feet, plus split in two. Second question is, using a fan in this setup, is it better to push air through, or pull air through?
You're going to need an 8" fan. 8" intake to an 8x6x6 wye to 2 6" vents through lights back to 8x6x6 wye to 8" fan to 8" exhaust.
Chart? Chart. However, do I use the fan to blow air through, or suck air out? I like. Instead of having my end that isn't attached to the fan though, can I just have the tubes run out of the grow env? Why do I need to have it come back together?
I have it coming back together so you can use the fan to pull the air through the hoods and directly out the exhaust. You really don't need the wye at the beginning, it's just a personal preference on my part.
OK, so I assume then that you are pulling out? Also, if I get an 8 inch fan, and then cut that down to 6 inch (because the hoods are 6 inch) that will be no problem right? BTW thanks. I'm new to designing a full grow room. Have the idea, but the more technical stuff... I'm guessing simply, and I don't want to do that.
Yes pulling out. You won't have a problem reducing to smaller ducting as long you are using a wye before doing any reducing to multiple ducts. You'll run into problems and create issues if you reduce your ducting before the wye. I would go with the 8 inch fan due to the fact of how much ducting you will be pulling through. You can always slow a higher powered fan down but you can't speed an under powered fan up.
I don't know if that sound confusing but i'll try and write an example. 8 inch to 8x6x6 wye to two 6 inch ducts ok. 8 inch to 8x6 reducer to 6x6x6 wye to 6 inch ducts not ok.
Just a note. The CFM of the fan is more important than the size. Each of your hoods have about 5 CF of space inside, x 6 = 30 CF. A 300 CFM fan would completely exhaust the hoods every minute. A 900 CFM fan every 20 sec. Etc.
Yes CFM is very important I have 300 + on each hood. So I run 740 CFM fan every 2 hoods. I can touch and hold my hand on the hood and glass right under a 1,000w HPS. It is warm on the glass but that's it. You may get away with less with 600's but you don't want excess heat. I don't run them together they each have their own intakes and exhaust. I run a passive run from outside that I conect each hood to then each hood gets connected to a y which gets sucked through 1 740 cfm 8 inch fan with two mufflers on both ends and then into a big scrubber. Don't really need a scrubber in a closed syatem but I have it anyway.
Sounds like a good set up. I need to bump my fan up a bit. I switched to a Magnum hood. It gives me great coverage for my set up but it's running just a little hot. I am running a 260 CFM so I will either get a bigger fan or try running one on the intake as well and see what that does.
On my upgraded setup I am going to be running it similar to my excellent pic that I posted. A couple differences is I will be running a 10" vortex split to 4 8" Magnums hoods, 2 on each side. I know about the arguments over pushing and pulling but I prefer to push with a higher power fan. That being said I have had more success with bigger fans at the beginning of the line pushing through the hoods. My temps seem to remain lower than using the fan to pull. Also something that might be worth mentioning is keeping the vent system for the lights completely separate and sealed off from the rest of the room.