Ventilation Question

[Budwiser0908]

I have a 24x15x8 room with six 1000 watt bulbs that are setup in 2 rows of three. I have a 12 in 1700cfm max fan in the room that I had planned to use to exhaust the room. It is connected to a y pipe so there are 2 exhaust ducts in each corner of the room. The lights have a 770 cfm fan connected to them and the exhaust for the lights and the room y together to exit the room by one roof stack. The 12 inch fan has been reduced to fit on my 8 inch flexible duct throughout the room. I am trying to get 3-4 air exchanges per minute in the room, however when I use my cfm meter at the exhaust grills it only reads 250-280. Meaning the air is being sucked out of the room at 250-280 cfm from the two inlets even though the fan is 1750. Is this enough or have I over engineered this thing? I am trying to create enough neg pressure where I wont have an odor issue. I also have 3 large scrubbers that dump the scrubbed air back in the room and an 8 inch passive intake...any ideas or suggestions would be appreciated

 

[ScrOGer]

We have the same light set up. i too am running 6x1000w with 8" ducting. I don't understand why you are having an issue.

I use the maxfan 14" connected to a CANFilter 150. The fan is pulling 1700 cfm from the room, thru the scrubber, and exhausting at a little over 1200 cfm. (I need about 250 cfm per hood to cool it.) It gives me enough to push thru 4 lights, then to an 8" fan (747 cfm) that connects via a "y" and pushes thru the last 2 lights.

Remember that each foot of ducting will reduce you actual cfm of air being moved. This is why i shoot for 250 cfm per hood, as it is just a little bit more than what i really need. I compensate for the couple feet before the first light, the 2nd fan, and the remaing length of ducting to get it out of the room.

Remember that your fan is listing the cfm rating that is within 0-1feet from the fan itself. 1700 cfm without a filter will move 1700 cfm of air over a distance of less than 1 foot. you will of course have a significantly lower reading at the end of the ducting run.

So it looks all is good. you start with 1700 cfm, and after running thru your lights, you have a reading of 200 or so. if my math is correct, you used 1500 cfm to cool 6 lights. 6 x 250 =1500, so you would have 200 cfm left over to actually keep the air moving towards it's exit point.

In case you are wondering with i use a 14" versus 12", as they are the same cfm rating. The 14" maxfan draws half the watts and is actually more quiet than the 12 and 10" maxfans. the 14" costs more to purchase, but actually costs less to operate, therefore i save more on energy bills than the difference in price at the store.

I hoped that helped.

 

[ScrOGer]

Here's a pic of the set up, to see if you are running the same as me, so the example above makes sense.

The canfan and filter are in the lower left hand corner.

the red arrows indicate the flow of the air from the fan, then #14 is the 747 cfm fan used as a booster.

 

[Budwiser0908]

Here's a pic of the set up, to see if you are running the same as me, so the example above makes sense.

The canfan and filter are in the lower left hand corner.

the red arrows indicate the flow of the air from the fan, then #14 is the 747 cfm fan used as a booster.

Thanks ScrOGer. It now all makes perfect sense. I wish we had spoken prior to my buying 2 of 12 inch maxes. The other one I use to exhaust the air in my veg and clone/mom rooms. THey are a little loud, but I find that after they run awhile they quiet down. Also, I covered mine with dynamat which makes a definite difference. The difference between our setups is that you exhaust all your air thru a scrubber where I have mine split off with two long duct runs and mounted in the ceiling. I think I like your configuration better. My only question is that I didn't know they made a filter that wold handle those kind of cfms. What size and brand is it?

I also found that you have to completely tape all the seems around the reducers and make sure all your duct connections are not leaking air. SInce our setups are so similar, I'm going to PM you if you don't mine and ask some more questions. I just started my first grow so I'm still tweaking and adjusting both rooms and my processes.

 

[Budwiser0908]

Oh and PS in your diagram what is 5,6, 10,11,and 15 out of curiosity?

 

[ScrOGer]

Oh and PS in your diagram what is 5,6, 10,11,and 15 out of curiosity?

With regards to hte numbers...There is a break down here:


5 are 2 32 gallon cans with lids (for R/O water)

6 is the growonix 300Gpd R/O machine

10 is a 24K BTU A/C

11 are doors

15 are honeywell 900 turbo fans for circulation. They are cheap and quiet, near silent for 13 bucks each at casa de pot.


The scrubber is CANFAN filter 150

I may have read the reply incorrectly, but i dont push thru the filter. i pull dirty air into the filter (sucks air into the filter) and blows thru the hoods. Since my ambient temp is always in the lower 70s, i am blowing cool ir thru the hoods, so they do not radiate as much heat. those raptor hoods are like warm rocks just heating up the room, if they are not cooled enough.

 

[Budwiser0908]

Holy Crap...we have almost identical setups with a few exceptions. I have a 10x10 Veg Room where I have 3 1000 watt Raptors with 5 bulb T5's on 3 of the walls mounted vertically, and another 10x10 clone/mom room which has 3 8 bulb T5's suspended.

I have been putting this together over the last 3-4 months and am almost ready to fire it up. In my original configuration in the bud room where the 6 raptors are located, I had set it up where the raptors where being cooled by rooms air conditioned air. I re-thought this and decided to instead pull the air from a crawl space above the suspended ceiling. I did this to first also create negative pressure in the crawl space area to keep any odor that wandered there from escaping and also I was concerned about sucking all the cool air from the room... in retrospect maybe that air (at least in the summer) will not be cool enough to cool the lights?

Thanks for info on the honeywell fans. I was about to spend 50 at the local hydro on some Airkings.

 

[ScrOGer]

The honeywell fans are 9 or 10" fans. they are a so rad. uber quiet and have three speeds. they do not oscillate but in combination with the other fans there is awesome air movement.

 

[ScrOGer]

Maybe your local hydro guy can order them for you, if he has a honeywell account. My local does not. so i had to go HOME depot. I will always make a priority to shop with my local first. home depot wont go out of business if a few people do not shop with them, whereas a local guy would feel the effects of the hurt, if you know what i mean.

 

[Lemony Skunkit]

That will be more than fine! And I seriously doubt you will have an odor issue either