Large Room Ventilation and Odor Control HELP PLEASE!

GetAhead

GetAhead

Well-Known Member
I am looking for a bit of ventilation/odor control help. I am dedicating a portion of a workshop to cultivation (it already has a wall dividing it in half). The measurements in the part I’ll use are 12 X 8, with a height of 8 feet, sloping to 7. As such, the cubic area is about 720 ft3. Since this is an entire room and wholly separated from the house, I am thinking that I can use either a ceiling or wall exhaust fan (or even exhaust into the other half of the shop for added stealth) and maybe use a hole near the floor for inflow.

However, using the 3-5 per minute rule for refreshing the air supply and helping to control temperatures, we are talking 2160-3600 CFM for God’s sake. Even finding an exhaust fan of this side leads you to somewhere like Grainger and, when found, ain’t cheap. We’re talking about $350 for a 2,000 CFM model. But, if that is what it takes, I guess that is what it will be. What does anyone else do with a room of this size? And what about the inflow and exhaust holes? How does one control light? I can see maybe running angled duct work for the inflow but I was not planning to use ductwork for the outflow….

Second, but just as importantly, what about odor control? I MUST have excellent odor control given the location of the shop in juxtaposition to my neighbors. The in-line, ducted filters are easy to find, but what does one do if using a wall or ceiling fan?

I am hoping I haven’t bit off more than I can chew, or afford, by having the luxury of such a big space. I mean for a small little closet, there seems to be info out the ears, but not for larger areas. Maybe I need to look at sites more concerned with vegetable gardening. (?) Any advice considered, even with respect to topics I might not be considering. Thanks.
 
recvryjst42day

recvryjst42day

Well-Known Member
As for odor controll, I am not sure how you would cover up almost 650 ft3 worth of good old smell, but I am no expert so wait for more responses they are sure to come! Good Luck and Happy Growing!
 
GetAhead

GetAhead

Well-Known Member
recvryjst42day said:
You can add supplemental CO2 by propane burners, and leave the room static.
Click to expand...
I'm thinking that I will need circulation since it is an unheated/cooled shop. Being in the Bay Area, CA, the temps will be mild and steady for a few months when I am ready to go (late-Sept.) but I think the place will warm too much in the day to go without venting.

Of the total volume of space, maybe a third of that will be in grow (I am HOPING to establishing about 8-10 bushes), but the size of the room is the determining factor with respect to circulation, no?
 
recvryjst42day

recvryjst42day

Well-Known Member
You could always go with Air Conditioning to remedy that, but remember grow rooms that are that size are usually close to commercial, if not already commercial, and cost alot of money to power and start up. I would personally divide the room again. And yes, the ventilation is in respect to the size of the grow room. pretty sure you'd have no problem with a 6x5 for about 8 plants.
 
videoman40

videoman40

Well-Known Member
Actually no, its how many watts are used for HID lighting that determines how much heat is given off, and hence how much ventilation is needed.

If memory serves me right, you take the watts, lets say 400 watt light, times 3.2 than divide by the cfm of the fan, something like this:
400x3.2/500cfm=2.56
This means that if you use a 500cfm fan, the temps will rise about 2.56 degrees over the ambient temperature.
I hope this helps you.
Peace

GetAhead said:
I'm thinking that I will need circulation since it is an unheated/cooled shop. Being in the Bay Area, CA, the temps will be mild and steady for a few months when I am ready to go (late-Sept.) but I think the place will warm too much in the day to go without venting.

Of the total volume of space, maybe a third of that will be in grow (I am HOPING to establishing about 8-10 bushes), but the size of the room is the determining factor with respect to circulation, no?
Click to expand...
 
GetAhead

GetAhead

Well-Known Member
videoman said:
Actually no, its how many watts are used for HID lighting that determines how much heat is given off, and hence how much ventilation is needed.

If memory serves me right, you take the watts, lets say 400 watt light, times 3.2 than divide by the cfm of the fan, something like this:
400x3.2/500cfm=2.56
This means that if you use a 500cfm fan, the temps will rise about 2.56 degrees over the ambient temperature.
I hope this helps you.
Peace
Click to expand...
Well, it is a start. I have 1000w light on order and it is easy to figure the rest, given the 3.2 (whatever that constant stands for). It doesn't seem to make sense that, in my case the need for about a 1250CFM fan (based on that formula) that the rise above ambient temp would be 2.56 degrees regardless of room size. (?)
 
recvryjst42day

recvryjst42day

Well-Known Member
GetAhead said:
I'm thinking that I will need circulation since it is an unheated/cooled shop. Being in the Bay Area, CA, the temps will be mild and steady for a few months when I am ready to go (late-Sept.) but I think the place will warm too much in the day to go without venting.

Of the total volume of space, maybe a third of that will be in grow (I am HOPING to establishing about 8-10 bushes), but the size of the room is the determining factor with respect to circulation, no?
Click to expand...

I thought you were talking about the room being warmed by the outside temperatures.

And Videoman, sad part is I used your thread that contained that formula for my new air cooled hood, and STILL forgot about lmao.
 
videoman40

videoman40

Well-Known Member
Pretty much, yes. Unless you have a huge factory to grow in, it assumes typical room sizes, like 12x12 and smaller. 1250cfm sounds about right to me.
You dont have to believe it, just try it and see for yourself.
Home depot has inline fans cheap. 8 inch, 500cfm fans are about $30.00
Peace

GetAhead said:
Well, it is a start. I have 1000w light on order and it is easy to figure the rest, given the 3.2 (whatever that constant stands for). It doesn't seem to make sense that, in my case the need for about a 1250CFM fan (based on that formula) that the rise above ambient temp would be 2.56 degrees regardless of room size. (?)
Click to expand...
 
GetAhead

GetAhead

Well-Known Member
videoman said:
Pretty much, yes. Unless you have a huge factory to grow in, it assumes typical room sizes, like 12x12 and smaller. 1250cfm sounds about right to me.
You dont have to believe it, just try it and see for yourself.
Home depot has inline fans cheap. 8 inch, 500cfm fans are about $30.00
Peace
Click to expand...
Oh, it's not that I don't believe. No need for back arching or anything. Ha! ;) Just found it counterintutive, but it wouldn't be the first time my intuitive bone was off.

Yes, recvryjst42day, I WAS considering both outside air temp and the temp from lights - but the climate here is SO mild mid-Septenbte - November, that it isn't a huge issue. Oh yeah, forgetful are you. Wondering why.... :blsmoke:

Videoman, do you think an inline fan (three in my case) is the way to go when I really don't need duct work, or are you thinking an inline so that a charcoal filter can be more easily adapted? Thanks.
 
beenthere donethat

beenthere donethat

Well-Known Member
The Home Depot fans aren't powerful enough for our needs...not when you factor in filtration..which is gonna be a *must* if you are serious about this hobby. The Home Depot fan is WASTED CASH for yer size of space.

FWIW...this is the standard formula used in the industry/by many hydro shops for fan size....

l x w x h divided by 2. Take that number..and buy the next largest rated cfm fan for your room.

Yer room would work out like this, getahead...

l x w = 96 x 8 (h) = 768 768/2= 384 I would bump up to something like a Can Fan 440cfm 6" inline fan for that space. That will give you a bit of extra ooomph...and if you need to expand it might carry the load of some of that expansion later.

but don't mistake that cfm rating for a "like' cfm rating in a Home Depot (Suncourt) plastic blade duct BOOSTER. Those aren't *anything* like an inline fan...not even close. They are merely a peice of ducting...6 or 8" with a crapola fan inside that moves very little air. I GUARANTEE it won't move air through the CHARCOAL filter you really need to buy if you are serious about odor control. These are matched to the cfm of the fan....and the combo is gonna set you back about what an oz of hydro bud will cost ya. That SUCKS..but not as badly as JAIL DOES. Keep in mind that the filter will last you 2 years or so...or roughly 10-12 grows. $30-40 per grow is cheap insurance and you can PACK THAT ROOM FULL IF IT DOESN'T STINK and make the cost of the filter back in savings in no time at all.

good luck

bt dt
 
GetAhead

GetAhead

Well-Known Member
beenthere donethat said:
The Home Depot fans aren't powerful enough for our needs...not when you factor in filtration..which is gonna be a *must* if you are serious about this hobby. The Home Depot fan is WASTED CASH for yer size of space.

FWIW...this is the standard formula used in the industry/by many hydro shops for fan size....

l x w x h divided by 2. Take that number..and buy the next largest rated cfm fan for your room.

Yer room would work out like this, getahead...

l x w = 96 x 8 (h) = 768 768/2= 384 I would bump up to something like a Can Fan 440cfm 6" inline fan for that space. That will give you a bit of extra ooomph...and if you need to expand it might carry the load of some of that expansion later.

but don't mistake that cfm rating for a "like' cfm rating in a Home Depot (Suncourt) plastic blade duct BOOSTER. Those aren't *anything* like an inline fan...not even close. They are merely a peice of ducting...6 or 8" with a crapola fan inside that moves very little air. I GUARANTEE it won't move air through the CHARCOAL filter you really need to buy if you are serious about odor control. These are matched to the cfm of the fan....and the combo is gonna set you back about what an oz of hydro bud will cost ya. That SUCKS..but not as badly as JAIL DOES. Keep in mind that the filter will last you 2 years or so...or roughly 10-12 grows. $30-40 per grow is cheap insurance and you can PACK THAT ROOM FULL IF IT DOESN'T STINK and make the cost of the filter back in savings in no time at all.

good luck

bt dt
Click to expand...
Whoa, I am very encouraged by this but also rather confused. The FAQ on this site would call for 2,100 CFM minimum, Videoman says 1,250, and now you suggest 384 and you espouse not scrimping on capacity in view of filtering at that! I am confused.

Why does everyone mention inline fans when I do not see a need for duct work? Maybe my nomenclature is erroneous but I though inline meant inlin with duct tubing. Or, is it just because one needs an inline to couple with a carbon can?

Finally, any thoughts as to not letting in light at inflow or exhaust?
 
beenthere donethat

beenthere donethat

Well-Known Member
Look at this site...I think it will make sense and is stated plainly..and when you use the formula you will wonder WTF they are talking about ventilating in the FAQ's here...

The exhaust fan calculator

it also addresses reflectors and inlines/charcoal filters ...etc.

my figures were a bit strong according to this site.. I still like MORE air than less. I have a 737 cfm in a room same size as you speak of but 2 ft taller...

bt dt
 
WillieNelson

WillieNelson

Well-Known Member
If you go through the roof, fuck filtration. If you have cops on your roof its too fucking late anyways. Sit on your front porch with a shotgun to keep neighbors at bay.
 
GetAhead

GetAhead

Well-Known Member
beenthere donethat said:
Look at this site...I think it will make sense and is stated plainly..and when you use the formula you will wonder WTF they are talking about ventilating in the FAQ's here...

The exhaust fan calculator

it also addresses reflectors and inlines/charcoal filters ...etc.

my figures were a bit strong according to this site.. I still like MORE air than less. I have a 737 cfm in a room same size as you speak of but 2 ft taller...

bt dt
Click to expand...
Thanks. Based on what I've seen elsewhere I was ALREADY wondering WTF abiut the FAQ here! ;)
 
beenthere donethat

beenthere donethat

Well-Known Member
I thought the same thing about going up through the roof, Willie...but you could still smell a skunk smell all the way out in the road so BAM...out came the wallet and on went the charcoal filter.

I've never smelled a thing since.

bt dt
 
GetAhead

GetAhead

Well-Known Member
WillieNelson said:
If you go through the roof, fuck filtration. If you have cops on your roof its too fucking late anyways. Sit on your front porch with a shotgun to keep neighbors at bay.
Click to expand...
You know, I was wondering about that, but I am no risk taker. Can't afford to be, if you catch me drift. I was originally considering a ceiling fan WITH filtration. I figure if it is going out the rook it will STILL smell. No?
 
beenthere donethat

beenthere donethat

Well-Known Member
LOL, getahead.

My info included...you should see the same basic info...or close to it...at 3 DIFFERENT sites before you believe it to be true. Some sites..uhummm... merely cut/paste info from other sites as their FAQ...or let "anyone" post info in the FAQ...and most of the time that info is out of date or untested by the poster themselves..so it's not always "good" info, IMO.

search "exhaust fan calculations' and you will find all sorts of info
 
WillieNelson

WillieNelson

Well-Known Member
Yes, but using the idea that your warm air will rise even above the highest point of your roof, the smell should be zero unless your neighbor lives on your balcony. I vent a very large space through a roof vent(unused chiminey) with zero smell at ground level. It could be that I live in an area with low humidity(and no neighbors), but even then i dont think its going to drift that far.
 
GetAhead

GetAhead

Well-Known Member
WillieNelson said:
Yes, but using the idea that your warm air will rise even above the highest point of your roof, the smell should be zero unless your neighbor lives on your balcony. I vent a very large space through a roof vent(unused chiminey) with zero smell at ground level. It could be that I live in an area with low humidity, but even then i dont think its going to drift that far.
Click to expand...
I appeciate the input, Willie, but I ain't a riskin' it. This shed is at the back of my property and sits just inside a fence. If the back neighbor stood against the shared fance, he'd be no more than 15 feet from the ceiling vent. I understand the warm air rises concept, but 15 feet is scaring me WITH filtration and one reasson why I thought of venting into the adjoining shop space.
 
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