How Much Ventilation Do I Need in My Grow Room?

Calculate the cubic footage of the space you're trying to ventilate. From everything I have researched, the golden standard is enough air movement to replace the air in the room within five minutes. If you don't have heat issues then I would say that calculation would do. But when you're dealing with heat and excessive moisture issues, you would want to vacate the volume of air within 1-3 minutes. If heat isn't an issue and moisture isn't as well, I would stick the five minute rule and implement Co2.
 
Im more worried about how long the exhaust run is. Its 30' with 90deg elbow. The room is 196 cubic, so the pnmp being 165 cfm's it should only take approx a minute to vacate. So to me that says the fan is fine for a standard application. Its just the length it has to exhaust that im so confused about. The 30' exit out of the house isnt optimal id rather go 45' but understand that im pushing it. Also i know about booster fans and am willing to use one if i have to. Sorry if this is poorly written im on my phone and its a pain. Thanks for your quick reply elious
 
As for implementing co2, im not there yet bro, just getting goin. I research constantly and understand it but i just got to get a grow under my belt
 
I hear you. I'm in the same boat really. As for the length of pipe, I dont think that should be too much of a factor but the 90 degree angle could slow it down a bit. I have the same thing going on except my pipe isn't as long (approx 20-25 feet from the 90 degree). I have a much larger fan, filter and volume to consider so I don't thonk what I'm experiencing will help you. My fan is 1000+ cfm and the room is a shade under 900 cubic feet. Although, I have the room separated and the set-up has the intake in one room, vented through into the second room through three snake pipes and then through the filter and past the 90. I don't think you should have problems though. Its a small enough space with a fan that can handle more than the volume in question. I say you should be good man.
 
I was just reading that you want to remove the volume of air 1-3 times EVERY MINUTE!! I personally think this is a but much. I'm pretty sure they're thinking in terms of extreme heat. For sufficient Co2 replinishment, another article i read said removing the volume every five minutes was enough. I guess it realky depends on the operation (wattage, size, ambient temperatures etc.)
 
What i meant was in theory thats what my 165cfm fan should do for my 196cubic foot room. Approx. Less the elbow and scrubber and length of exhaust run (friction). Just meant its well under the 1 in every 5 minute mark.
 
Im insulating the ceiling in the room and building a sound insulating box around fan and hanging it from bungie cords. Also i plan on building a fan muffler. And there is a carbon scrubber atrached to the intake of the fan.

My question is....will all that make it quite enough so that it wont be heard from the main floor of the house? Whats your thoughts people??
 
With all that you shouldn't hear much... Maybe a light humming sound.
 
Hi,

It all depends on the amount of light (=heat) that you use in your grow room. I always use this formula; bulbs x watt / 2 = outlet.

So for 3 x 600 watt light bulbs you need a 900 cfm outlet. (3x600=1800 1800/2=900). And for inlet take half of the outlet to make sure you create a vacuum and no air escapes.

Robert
 
I ran into a similar problem at a job I had 2 years ago. Essentially, because air is made of matter it has weight. With that said, when constructing your system you have to take into account a few different things such as runs, bends, turbulence and of course fan ratings. I don't pretend to know any formulas for calculating what is needed to effectively get the job done, I just know from experience that too long of a run, the flow of air slows down and stops. this stopped air creates resistance which will then sabotage your system. I'm currently also designing a box that will employ ducting designed into the walls on both sides. I've generally figured out the direction of flow, how many cubic inches is in each compartment, and how many 90s and 180s there are, but haven't the faintest clue how to tabulate all that data into a mathematically efficient air moving system, so I'm just gonna shoot for overkill and dial fan speeds back from there till I find the "sweet spot" that efficiently manages the air, heat and noise.
 
if im growing in a 2x3x10 closet and the only way in and out is the one door, how should i vent it? and intake at the bottom and outgoing at the top? the door is kind of old so it isnt solid it has like louvers all the way down... should i just leave it as is since air already flows in and out naturally? or will that leave to much of a smell coming from the room since it will never go through a filter?
 
If you're not going to use a filter, I think you'll find that closing the louvered door will help none and decide maybe to get a filter. I am in a similar spot to you and my in/out goes through the same door. So I have the in going in through the bottom and the out will be ducted out the top to separate the 2. My plant is very small and if I get as close as 2 feet, I can smell it, so I will be using a filter very soon. Assuming you are not growing many, maybe you could use the dryer sheet in a tube trick to treat some of the odors until your budget opens enough to spring for a filter. I'm a DIY kind of guy, so I like to build everything to save a buck. I found 20 LBS of activated carbon on eBay for $50 and can use that to build one or more filters to suit my design. Maybe you can look at that option in the future. there are plenty of DIY Carbon filter threads on this site, as well as a few youtube tutorials.
 
ive never had to worry about ventilation as ive always grown outdoors. where would i install a filter? into the ventilation system? or is it free standing
 
Everyone I've seen thus far, both OEM and DIY are a cylindrical mesh with an inner cylindrical mesh and carbon in between. This is usually mounted somewhere in the grow space and attached directed, or via hose duct to an inline blower type fan before exhausted. I don't know if anyone has ever built or used an inline filter, but I already have the activated carbon and being as though I am tight for space, I will likely build my own inline with hopes that it works. If you wish to see a version of inline filter I had originally intended to build, see my journal link below and the design is in the first post. But since I had to revamp my entire box design, I also plan to redesign my filter, and I may even go with the traditional can filter design, I don't know yet...
 
so im basically looking at an intake a little above floor level with an inward fan to pull in fresh air, can do a filter on the way in to prevent bad air, bugs, etc.. And then an output vent at the top with a outward blowing fan and a carbon filter. Sound right?
 
More or less. Just design your space to suit your wants and needs. If on a budget DIY (it's funner that way), if money is no object, get all the bells and whistles. Spend a few hours looking at people's grows on YouTube. Even though most of'em don't talk about their setup, you can still see it and get ideas of your own.
 
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