80ft3 Closet Ventilation - Inline CFM + Duct Size Q's

[Kingsnake235]

Hey there!
not sure where this should be posted; please feel free to move to somewhere more appropriate if necessary!

I am in the process of readying for my first personal grow (link to relevant thread in signature) and I have a few specific questions regarding ventilation, fan size and the CFM relationship to the connected ducting.

My space is not setup yet, I am trying to sort out the odds and ends while i have some things coming in the mail.

so:

i will be running 600w HID on 6" cool tube; my question is, should I just immediately use all 6" ducting and a 6" fan @ 160cfm? or would there be any advantage or disadvantage to stepping up/down the fan or the ducting?

my options for fans at local HW shop are

4" @ 52dBA and 60cfm (80 "boosted" whatever that means)
5" @ 51dBA and 140cfm 220 boosted
6" @ 50dBA and 160cfm 250 boosted

they say they are multi speed, i assume that is in reference to "boosting", but not sure what that means or how to achieve this, possibly with a fan controller? ( i have read much about this and while it is not "advised" to wire a controller onto an AC fan, i know a lot of people have had no issues when using something like a ceiling fan dial or some other higher draw switch)

will these fans work?

my space is 2x5x8 for 80ft3 so 160cfm a minute will refresh twice a minute. is this too much ventilation?

i will build a carbon filter at whatever size ducting/fan i decide on, with activated carbon internally and a fabric filter on the outside and have read it could reduce cfm by 30%, is that an accurate reading? putting it to around 140cfm.

if i step the ducting down to a 4" and use the appropriate fan at 60/80cfm, will this still cool the 600w light if arranged as such:

[filter]>>>>[light]>[fan]>>>>[output]

or will i need the extra power of a larger fan to cool the light? again, if larger, how much cfm is TOO much? i don't want to have to use co2 or put the fan on a separate timer to the light.

it is also entirely possible that i am over thinking this and i should just use a 6" fan with 6" ducting and wire a controller onto it to adjust the speed down if necessary. Or a independent light cooler and separate exhaust?

it is currently pretty cold in my area so heat conservation is a consideration, outside temps around 0-5*c during the day and -2 to 1 overnight with humidity from 60-80% outside - i can keep the ambient temperature in the house around 12-5*c (have not measured indoor humidity yet) so i need to increase the temp in the grow by 10*c or more consistently and would like the fan to be somewhat quiet, but don't have the funds to drop $100+ on a fan.

thoughts?

 

[Bearded Budz]

I m a rookie here buddy but I found a wicked site where I referenced all my light, fan, carbon filter and pretty much anything else you could ever think of! And prices are the best I ve ever found. Grow Lights Canada. Canada's #1 source for Grow Lights / HID Lights and Hydroponic Equipment Check out their packages and how they gauge things together if info is all you want.
I actually ducted the 6" line from the carbon filter/fan right over to the intake on my furnace and turned turned the furnace fan on constant so it circulated that warm air throughout my house to help offset the lighting costs, and it actually works great! No smell!
Hope this helps dude, if I can do anything else just say the word! We re here to help

 

[Kingsnake235]

hey! thanks for the reply; i'm browsing it now. Those prices are really good, and surprisingly in $CAD, the duct fans are much cheaper than the local HW store offers, and they even stock panda film, which i haven't been able to locate in canada. thanks for the link!

i am thinking i will just use the 6" fan i can buy locally and step down to 5" ducting so save on some space then ill build a
4"ID/5"OD carbon filter >>> run the 5" line >> stepped up to the 6" cooltube >> then have the 6" fan pushing a 6" exhaust out the closet ceiling into the open air 12' vaulted ceiling to recycle the heat

after some more reading, it seems i should recycle the air at least twice a minute meaning ill need the 160cfm fan for the 80cf space at minimum.

thanks for your input!

 

[AKgramma]

I actually ducted the 6" line from the carbon filter/fan right over to the intake on my furnace and turned turned the furnace fan on constant so it circulated that warm air throughout my house to help offset the lighting costs, and it actually works great! No smell!

I can't picture this. Is the 6" line linked INTO the furnace intake, or does it just come within the vicinity of the furnace intake? I would worry that the addition of extra load on the intake would reduce the amount of air it need to fire properly. This could cause CO2 problems in the house.

 

[Kingsnake235]

I can't picture this. Is the 6" line linked INTO the furnace intake, or does it just come within the vicinity of the furnace intake? I would worry that the addition of extra load on the intake would reduce the amount of air it need to fire properly. This could cause CO2 problems in the house.

it sounds like he has a 6" fan pushing air from the grow thru the exhaust and that accelerated air is then picked up by the furnace fan, without the furnace running, to circulate the heat from the grow into the house, essentially using a 2 fan system for a longer ducting run.

not sure about co2 issues, but it doesn't sound like the furnace fan would have to work too much harder to pull the already accelerated air into the house.. although, if the furnace fan out powers the grow room fan then it could cause the grow fan to act as a forced air booster, thereby increasing the speed of the grow fan, but yes, putting more of a load on the furnace fan.. hmm.. thats out of my league haha i have no idea as to the technical details of such an application..

 

[AKgramma]

Just using logic here. Since you have to periodically clean the furnace filter to keep the air circulating efficiently, and to ensure an efficient burn, it seems logical that any extra strain on the intake, if it is restricted in any way, will cause the flame to burn inefficiently, giving off lethal CO2.

They don't make furnaces to handle anything higher than just cooling and heating a certain sized residence. Don't need to be a mathematician to figure that out. Just check the specs on the model of the furnace. If the outlet from the grow room is NOT physically connected to or blocking the intake, then it's OK. You can replace the filter with a odor-removal filter that fits your furnace. I beleive they have a thin layer of charcoal on the filter medium.

 

[Bearded Budz]

I can't picture this. Is the 6" line linked INTO the furnace intake, or does it just come within the vicinity of the furnace intake? I would worry that the addition of extra load on the intake would reduce the amount of air it need to fire properly. This could cause CO2 problems in the house.

Sorry guys i was quite vague when I described this. We have an electric furnace first off and it s located in another room just on the other side of my flower room. I have a 440 cfm fan connected to a 6" carbon filter that's ducted TOWARDS the furnace intake, it isn't tied directly into the furnace, just directed towards the intake. Probably not efficient but I didn't want to restrict anything like you guys suggested. I also set up a dehumidifier in the furnace room as well, but here in Manitoba humidity usually isn't an issue. My 8' by 8' flower room with a 1000w hps sits around 30C lights on and 20c when lights are off, humidity ranges from 53 to 35. The package I picked up can be found at Grow Lights Canada. Canada's #1 source for Grow Lights / HID Lights and Hydroponic Equipment under the 1000w with parabolic cover and 440 cfm fan/filter package. Sorry, for the misunderstanding guys, but yea it works pretty darn nice on the mildly cold days but now that it's getting really cold the heater s gonna kick on much more. Either way, my 1200 foot finished basement stays nice no matter what.

 

[AKgramma]

Sorry guys i was quite vague when I described this. We have an electric furnace first off and it s located in another room just on the other side of my flower room. I have a 440 cfm fan connected to a 6" carbon filter that's ducted TOWARDS the furnace intake, it isn't tied directly into the furnace, just directed towards the intake. Probably not efficient but I didn't want to restrict anything like you guys suggested. I also set up a dehumidifier in the furnace room as well, but here in Manitoba humidity usually isn't an issue. My 8' by 8' flower room with a 1000w hps sits around 30C lights on and 20c when lights are off, humidity ranges from 53 to 35. The package I picked up can be found at Grow Lights Canada. Canada's #1 source for Grow Lights / HID Lights and Hydroponic Equipment under the 1000w with parabolic cover and 440 cfm fan/filter package. Sorry, for the misunderstanding guys, but yea it works pretty darn nice on the mildly cold days but now that it's getting really cold the heater s gonna kick on much more. Either way, my 1200 foot finished basement stays nice no matter what.

WHEW! You thought this out quite well! It sounds like a good solution to odor control and air circulation. The temps are even lower than what I get in my grow areas here in Alaska. And I keep the heat register closed in the grow room. The lights heat the room.