How many CFM's to Ventilate/Cool My Hoods?

[baet]

Room = 400CF (5 x 10 x 8)

2 Air Cooled SunSystem2 hoods w/ 1000w lamps (ballasts outside room)

Separate inline fan for exhausting heat from lamps.

My question: How many CFM's should my inline fan exhaust to properly cool 2 1000w lamps?
Is there a rule of thumb for sufficient CFM's to properly cool a 1000w lamp?


For example, would a Vortex 6-inch 448cfm fan be sufficient for cooling 2 1000w lamps?

 

[baet]

bump

 

[MangoCat]

I have two Vortex 6" 448cfm fans cooling three 1000w lamps. One fan draws air out of a central a/c ceiling vent and pushes thru the lights and the other pulls the air out of the lights and blows it outside. This is sufficient if the flower room door is left open to draw in ambient cool house air, along with a couple oscillating circulation fans.

When I seal the room to run co2, which is most all the time, I need to add my 1 ton mini-split air conditioner along with a dehumidifier to keep temps and humidity under control.

Hope this helps.

 

[dtfsux]

I used a vortex 6" to cool 3 1000's. Did the job but probably pushed it. I think you would be fine with 2000 as long as you did not have any crazy bends in the ducting.

 

[baet]

mango cat- i'll also have an 8in vortex for purely ventilating the room with passive intake through a hepa filter. sounds like 1 6-inch vortex can do the job with 2 1000w lamps considering i'll also have an 8-inch for temp.

quick question mango cat: i won't have a/c for cooling lamps through ducting like your setup, but just having the 6-inch exhausting the heat from lamps will cool the bulbs sufficiently still, right? in other words a/c is not needed in order to cool hoods/lamps, obviously the addition of a/c being pushed through the hoods would work a lot better though.

dtfsux-no crazy bends, almost straight shot outside with only probably 1-2' ducting to exhaust. did you have a/c being pushed through your hoods as mango cat did?

 

[baet]

this will be my first proper indoor, thanks mango and dtfsux.

last indoor was sloppy and pests/bugs became an issue.

outdoor i'm very confident. indoors a whole 'nother game

 

[MangoCat]

baet, You should be fine drawing ambient room air through the hoods and blowing outside with the one 6" Vortex. Be sure to have the fan drawing air through the hoods and then blowing outside and you should be good to go. I would also put a 6 inch "Y" air duct splitter between the fan and the hoods and draw air out of each hood individually rather than drawing the hot air out of one hood and then through the other.

I'm in Las Vegas, so air conditioned air is all I've got access to right now (Thank God). When it cools off outside in the fall and I need to use the house heater, I will reverse the Vortex system and draw cool air from outside the house, blow/draw it through the lights and into the attic.

You may find you have to tweak things through the year as weather changes.

 

[milehighmedical]

.

 

[baet]

mango cat- "Y" duct splitter makes sense, i hadn't though of that, good idea, thank you.

But because my room is narrow and long "Y" splitters would have to be positioned between the two hoods, as well as between the fan and closest hood correct, such as:
[fan] -< [hood] >- [hood] ?
some ducting would have to go above the hood that is closest to the fan.

Because my lamps can't be positioned side by side with one "Y" connecting both hoods to fan, the ducting would have to get a little tricky.. would it be worth it?

okay, i think i over thought the whole ducting. i could probably easily get away with one "Y" splitter in between the fan and hood, and then run ducting around the side of the hood closest to the fan and connect to the farthest hood...


milehighmedical-exactly what i was looking for as far as air cooling guidelines. right on, i was wondering wether my setup would be sufficient or correct, and you just gave me the encouragement to put my plans to action.
what's a "HO fan" though? since a 6-inch HO fan does 2, and a 6-inch fan does 1-2...

 

[gdbud]

one thing to remember is if you use a "Y" you will need two dampers so that you can balance the air flow between the two lights. Other wise the light with the shortest duct or resistance will get all or most of the air flow leaving the other light hot.

 

[baet]

gdbud-that seems like a very important point ha. k+

 

[baet]

is it completely necessary to use a "Y" , could i get away with just pulling air through one channel of ducting through both hoods?

 

[ZackMorris]

Whats the math again for calculating proper cfm for an entire room? And how often should you exchange the air? As far as the original question, im a little confused. Where's the filter? Are you pushing or pulling through the lights and do you have one end of one hood "open" pulling air from the room? Whats your situation? How big of a priority is controlling the smell?

 

[gdbud]

is it completely necessary to use a "Y" , could i get away with just pulling air through one channel of ducting through both hoods?

Yes you can get away with just pulling air through both hood in a series and you would not have use a "Y" or dampers. You just have to be aware that the second light will be running a little warmer than the first light.
Below is a graph of the temperature rise of a given lamp size within a given CFM.

 

[baet]

CFM = cubic feet minute. CF= w x l x h of your space.
lots of factors determine what your fan size should be for your specific room.
fan should replace air in room once every 3-4 minutes at least. but if you want your fan to also help in cooling your room you should have a fan that can exhaust your room much faster.

no filter. no need to hide smell in my situation.

fan pulls air through hoods and then exhausts outside of room, pulling is more efficient than blowing.
yes, farthest hood is open enabling ambient air within the room to be pulled through the hoods

 

[baet]

gdbud- yeah, i just have no experience with dampers. i would like to run a "Y" , so i'll probably do some research.

if you could give me any pointers it would be much appreciated, such as where the dampers should be positioned, and especially how the dampers work.

do you position each damper between the fan and each hood?

 

[gdbud]

.................Damper
Fan------------|--------------
.............\ .......................\
...............----|-----Lightt.....--------Light
.................Damper

To balance the system take two pieces of string and on the end of each string tie on a piece of fabric then hang the string in front of each intake. Take the damper that the string is being pulled into the lamp the most and turn that damper down until both strings are being pulled into the light same amount. just play with it and you will get the idea.

 

[gdbud]

Ideally you should use two "Y's" then place the second damper at the same place as I shown on the first take off then run the main duct run 3 to 4 duct diameters beyond the last "Y" then cap it off. This extra length of duct will help to develop static pressure in the duct and make you system more efficient.

 

[milehighmedical]

.

 

[dtfsux]

dtfsux-no crazy bends, almost straight shot outside with only probably 1-2' ducting to exhaust. did you have a/c being pushed through your hoods as mango cat did?

no my room was sealed and I pulled air from outside the room and pushed through my hoods to another area outside the room.


Personally I would not bother with the y and dampers. This is two lights, not 20. I have run manifold designs as well that worked real but that was on larger setups.

But for two lights just get a good fan and pull straight through them