ventilation gurus help!!!

[disrupt86]

quick question,right know i have an ideal setup of 2 x 600 watt in a 5 x 10room,however i need another lamp a.s.a.p. up until this point the room gets ventilation from a seperate room and exhausts into our main room"wich gets pretty hot. im afraid by adding another lamp its going to affect my veg room.i need some input on my idea, i have 30 ft of 4 inch schedule 6 abs pipe.my plan is to run all three lamps with my current 6 inch fan then reduce to a 4 inch reducer" to accomodate the piping" and then there is a 15 foot straight run then one 90 deg bend and another 10-15 foot strait. my plan was to use a 150 cfm booster fan after the 90 to help move things along. oh also the 6 inch fan is 325 cfp pulling air. is there some formula to figure out, cfm x length x diam that i can use to help me out.

[disrupt86]

ok let me put this in a different format.does any one have 3 lamps linked together "ventillation wise" with a 35-40 foot run of 4 inch ducting.if so what cfm fans are you using.at the moment i have a 10 foot run with 2 600 watts and a 325 cfm. fan pulling the air. before i go ripping everything apart is there a minimum cfm rating for 3 lamps at 40 feet????

[fluid69]

i'm no guru, but here's a couple of links that helped me figure ventilation.

this one has some math in it, but you should be able to figure out your cfm:
http://boards.cannabis.com/indoor-growing/132514-noobs-guide-growroom-set-up-work-progress.html

and this one is all about fans:
http://boards.cannabis.com/growroom-setup/112273-fans-not-just-blowing-hot-air.html

[Rezinator]

Interested in this topic since for my next grow I want to do house-external exhaust - zero detection risk - aerial heat sensing wise, and of course do the ever coveted HID brilliance.

Still waiting to hear how "quiet" my new Elicent 6" Blower will actually be when it arrives - for my particular indoor stealth plan. I just thought maybe rhizome would need to know how much noise you can get away with security wise.

For long runs, I am still conceptually trying to wrap my ultra newbster brain around what wider fan and ducting widths can do - or demand - but with a focus on keeping Fan speed lower and, thus quieter.

Rhizome. You must try to flesh this out some time.

Correct me if my thinking is wrong, please.

4 inch ducting means - for these long runs- that this bros 6" Fan is going to have to scream. Right?

Am I wrong to assume that an 8" inch ducting would more comfortably (lower amperage draw - rheostated-down - fan speed) would keep fan somes down - yet still support the submitted 3x 600W heat exhaust scenario.

What if your indoor - mainstream social - situation requires no unusual hum, in other words. Not tryin to be a pain outta go into my signature, eh? Lol.:smokin:

[grey1223]

Haven't done three 600's but I do have two 1000's with a 6" venting system. I have fans everywhere. A/C, veg room and mom room plus 740 and 430cfm carbon scrubbers. A little noisy. Insulated duct reduces the noise a bit. I like to use more rather than less with fan size, then I use a 5 amp ceiling fan controller to adjust speed if I wish. 3 600's should be fine with 6" ducts but I'm not sure about the 4". Regardless, even the 4" will help some.

[disrupt86]

my current hydrofarm 454 cfm fan is pretty damn loud.its the only thing that gives away my hidden room that i spent a ton of money trying to make incognito. one thing i have done before and will be doing again for my big fan is building a box around it from fiber board and just set the fan in there,it works pretty well,this time around i was just anxious to try out the new setup.and its fine how it is,but im trying to vent my lights out side like Rezinator sed"hence such a long run of ducting...ill keep searching thanks guys.