New Setup - Ventalation Advice

[sneekymofo]

I've been growing with mixed results for a while now, and I have decided to upgrade from my micro-grow (150w HPS scrog - 2 plants per DWC 5 gal bucket) to a 600w HPS (1 plant per DWC 5 gal bucket). I know I need to upgrade my ventalation situation. I have the following questions:

1. If I use an air-cooled light, what size blower would I need to ensure that the heat from the 600w is exhausted from the room?
2. If I use another fan to extract residual heat and stinky air, can I just use a blower that will extract the square footage of the area once every couple of minutes? What about the overage to cover a carbon filter? (I'm a bit fuzzy on which math to use....) The room is about 168 ft2. Do I just divide the 168 by two then add 20% for the carbon filter?!?

Thanks so much for any advice! I didn't want to waste money (and noise) on overkill, but have had heat issues in the past..... I also can't have stinky air running amuck!

sneekymofo Reviewed by sneekymofo on 06-14-2010. New Setup - Ventalation Advice I've been growing with mixed results for a while now, and I have decided to upgrade from my micro-grow (150w HPS scrog - 2 plants per DWC 5 gal bucket) to a 600w HPS (1 plant per DWC 5 gal bucket). I know I need to upgrade my ventalation situation. I have the following questions: 1. If I use an air-cooled light, what size blower would I need to ensure that the heat from the 600w is exhausted from the room? 2. If I use another fan to extract residual heat and stinky air, can I just use a Rating: 5

[Prodaytrader]

I can answer the first. I have a 600w and a 4" vortex. I was running 100' of duct and found the fan not powerful enough to properly cool the lights. I have removed 50' of duct achieving mildly better results. It's apparent to me that I will need a much bigger fan. A 8" perhaps aught to do the job. I hope. I just ran across this in my own research:

Size CFM Amps Watts RPM dBA
4" 172 0.77 80 2500 49
6" 449 0.9 100 2600 49
8" 747 1.42 150 2550 54
10" 790 1.64 215 2510 57
12" 1140 2.42 296 2400 67

To me it looks like the 8" will be enough. It would only be mildly louder. I ended up suspending mine from the rafters but I must warn you that if you bolt it to a rafter, the vibrations will transmit through out the house. Better to devise a way to insulate the vibrations from anything that will transmit the sound.

[Prodaytrader]

There is in fact a complicated formula to figuring it out, I didn't care to learn it. The short answer it would seem is over 400cfm will do the trick for a 600 watt. So that's a 6" vortex style fan with probably as much as 100' of duct. A quick search revealed the following: 6" Fan - 79$ I believe I will order something along this line. Be careful that you don't get a bad 6" fan. Some of the ones I see listed on ebay range anywhere from 250 cfm to 450. So make sure you get one that goes at least 400cfm I recon.

[irydyum]

Here's a handy chart. It tells you based on wattage of light used, how many CFM you need to keep temps within range of ambient.

For example, from the chart, if you wanted to keep temperatures within 2 degrees of ambient with 600w of light, you would need 960 cfm of air exchange. Obviously as the tolerance gets greater, the CFM requirement drops.

There is another formula to figure out true CFM calculating bends and filters and such, and if you want that as well, I'm sure I can produce it.

Iry

[tinytoon]

6" vortex style fan and an organic carbon fiber filter should handle both cooling light and evacing air. Have 2 600w lamps being cooledby 1 6" fan and will be adding a 400w cooltube to the mix in a couple weeks. Room is 12x8x7 so use a second 6" to ventilate.

[Prodaytrader]

That's almost what I am going for. I have one 6" HD style duct fan, much lower cfm, fan pushing out at the ceiling and a 4" sucking out through the hood, but I think it needs to be a 6" as well to properly deal with the lights.

[sneekymofo]

Thanks to everyone for the quick response! Based on the input, it looks like a 6" or 8" Vortex should do the trick! I may go with the 6" to limit noise since I don't have much duct to push through (maybe 20 feet or so....).

So here is my next question: if I go with a 6" 449 CFM fan, what size carbon filter can I use? I see MAX CFM and MIN CFM ratings on some of the filters, but that doesn't seem to "tick-n-tie" with the actual CFM rating. Is there a rule of thumb? Can I use a 449 CFM fan to exhaust with a 200 max CFM carbon filter?

I ask because I'd rather spend the money on one "better" fan than two. If I can pull through the filter, then through the light, then vent with a single fan I'd have some extra moolah for other stuff. Thoughts?

BTW: I use an Ozone generator to manage smellies as well, but I only run it for 15 minutes per hour.

[Prodaytrader]

In terms of the filter being used at the intake point, that's fine. The 6" 449 cfm fan is designed to run at least the 20' u need, likely the 100' I need, as well as a filter. You will need to get a filter rated for the fan range your working with. What size filter do you need? I wouldn't go crazy, especially since you likely only have a few plants to deal with. Someone else will have to take this one but I would guess that if filters are rated for different air flows, then you would have to go for one that matches your air flow. In terms of using it up, well since you only have a few plants I would expect the filter to last much longer as it will take that much longer for the charcoal to become saturated to a point of no longer working.

[sneekymofo]

Thanks proday! I'll check out the 6" flange options in my price range and CFM range to be on the safe side. Once I get the room set up I'll start a grow journal!