growroom vent comments

Oscar · 03-15-2011, 02:12 PM

I dont know if this is the right spot to ask aquestion about grow room set up but here goes. I want to put my exhaust fan in the attic and duct down to the room, the total distance from fan to room will will require 25 ft of duct. In this situation I will be vacuuming the air out. If I put the fan in the room then i will be pushing the air out. with the exh fan in the attic for stealth reasons will there be a problem with CFM? My room is 125 cf, in basement.Will be using a centrifugal in line duct fan,rated at 3 times my rooms cf. but i got to go with stealth!!! that is the reason with installing the fan in the attic. Do i need to increase the fans CFM when using a carbon filter? can i install the filter in the attic? does in matter which side of the fan i install the filter? Will be using 4 inch ID smooth bore flex duct (smooth bore to reduce drag). Will also install a 4 inch fresh air duct with no fan because my room is below ground level and the inlet will be in the garage at 1ft from floor. One last question, will the lenght of duct be a factor in choosing a exh fan? Thanks

SmokeaJoint · 03-15-2011, 02:40 PM

Whats the fan's CFM to begin with? Also, if your fan is rated 3x the CFM for a 125cf room, I'm pretty sure your fine with 25' of ducting and a filter. Try to run the ducting with the least amount of curve in the path to make it most effective. Straight lines, yo.

Dandaweedman · 03-15-2011, 02:41 PM

4" pipe? is the whole setup 4"? The fan etc I mean.
and you are getting 375 cfm from a 4" fan?

Make a thread in the Nursery and I'll move your posts into it

Oscar · 03-15-2011, 06:50 PM

I posted a few questions about grow room setup after reading "grow room setup" in the GTGH nursery section, that was not the right place for my questions. I was told to post a thread here in this section and they would transfer my comments to this section. thanks be patience with me, Im not that familiar with this site. the only way to learn is to do it, just like growing!

Jester4yall · 03-15-2011, 07:02 PM

You got that right man!

Sugar420 · 03-15-2011, 08:26 PM

4" pipe seems skinny to me for that much volume at that distance, and i would be worried that a 4" fan rated at 375 cfm would be really loud.
normally the cfm rating of fans tells you what the fan does at sea level with no restriction. so actual real world preformance is usually not as great as the manufacturer claims.
i feel very skeptical that such a setup will really be stealthy and work well

dan?

Dandaweedman · 03-15-2011, 08:33 PM

I have to agree with V3d4. Most 6" fans max out in the 300's-400's cfm wise. A 4" should be about 120-200 TBH
Post up the manufacturer and model number of your fan and we can get more info on it.

Inline fans are build for exactly what you are wanting.
25 feet of duct is a long flow for a smallish fan though, especially with a filter on the end of it... or beginning either way.
But you use what you have in a lot of cases. Best way to test it out is borrow some perfume or something of that nature.
Shut yerself in the room and spray a bit. See how long it takes to get sucked up.
All you need is enough flow that the odor won't sneak out somewhere.

farmergiles · 03-15-2011, 10:14 PM

It's not just the noise of the fan you have to worry about but noise of the air moving through the duct as well.

Fans are usually more efficient pushing air rather than pulling (or vacuuming) it- having the fan in the attic pulling through 25' of 4" conduit will cause some air resistance. If the fan has to work harder it might make more noise.

Maybe put the fan in the growspace, place it in a box filled with blankets or expanding foam (or any other sound insulating material). This should work better even if you go with the long duct to the attic.

03-15-2011, 02:12 PM	#1 (permalink)
Oscar YaHookan Join Date: Mar 2011 Location: USA CORN COUNTRY Posts: 5 Thanks: 2 Thanked 3 Times in 3 Posts	growroom vent comments I dont know if this is the right spot to ask aquestion about grow room set up but here goes. I want to put my exhaust fan in the attic and duct down to the room, the total distance from fan to room will will require 25 ft of duct. In this situation I will be vacuuming the air out. If I put the fan in the room then i will be pushing the air out. with the exh fan in the attic for stealth reasons will there be a problem with CFM? My room is 125 cf, in basement.Will be using a centrifugal in line duct fan,rated at 3 times my rooms cf. but i got to go with stealth!!! that is the reason with installing the fan in the attic. Do i need to increase the fans CFM when using a carbon filter? can i install the filter in the attic? does in matter which side of the fan i install the filter? Will be using 4 inch ID smooth bore flex duct (smooth bore to reduce drag). Will also install a 4 inch fresh air duct with no fan because my room is below ground level and the inlet will be in the garage at 1ft from floor. One last question, will the lenght of duct be a factor in choosing a exh fan? Thanks

03-15-2011, 02:41 PM	#3 (permalink)
Dandaweedman Old School Join Date: May 2004 Location: At the Cabana Posts: 7,407 Thanks: 699 Thanked 760 Times in 613 Posts	4" pipe? is the whole setup 4"? The fan etc I mean. and you are getting 375 cfm from a 4" fan? Make a thread in the Nursery and I'll move your posts into it __________________ Hanging in the Cabana

03-15-2011, 06:50 PM	#4 (permalink)
Oscar YaHookan Join Date: Mar 2011 Location: USA CORN COUNTRY Posts: 5 Thanks: 2 Thanked 3 Times in 3 Posts	growroom vent comments I posted a few questions about grow room setup after reading "grow room setup" in the GTGH nursery section, that was not the right place for my questions. I was told to post a thread here in this section and they would transfer my comments to this section. thanks be patience with me, Im not that familiar with this site. the only way to learn is to do it, just like growing!

03-15-2011, 07:02 PM	#5 (permalink)
Jester4yall Spark It or Park It Join Date: Mar 2001 Location: Africa Posts: 3,667 Thanks: 2,782 Thanked 1,326 Times in 949 Posts	You got that right man! __________________ http://i.imgur.com/CTV2E.gif In matters of style, swim with the current; In matters of principle, stand like a rock. -Thomas Jefferson You will encounter many distractions and many temptations to put your goal aside: The security of a job, a wife who wants kids, whatever. But if you hang in there, always following your vision, I have no doubt you will succeed. - Larry Flynt

03-15-2011, 08:33 PM	#7 (permalink)
Dandaweedman Old School Join Date: May 2004 Location: At the Cabana Posts: 7,407 Thanks: 699 Thanked 760 Times in 613 Posts	I have to agree with V3d4. Most 6" fans max out in the 300's-400's cfm wise. A 4" should be about 120-200 TBH Post up the manufacturer and model number of your fan and we can get more info on it. Inline fans are build for exactly what you are wanting. 25 feet of duct is a long flow for a smallish fan though, especially with a filter on the end of it... or beginning either way. But you use what you have in a lot of cases. Best way to test it out is borrow some perfume or something of that nature. Shut yerself in the room and spray a bit. See how long it takes to get sucked up. All you need is enough flow that the odor won't sneak out somewhere. __________________ Hanging in the Cabana

03-15-2011, 08:26 PM	#6 (permalink)
Sugar420 Freedom Bird Join Date: Mar 2002 Posts: 6,138 Thanks: 41 Thanked 183 Times in 733 Posts	4" pipe seems skinny to me for that much volume at that distance, and i would be worried that a 4" fan rated at 375 cfm would be really loud. normally the cfm rating of fans tells you what the fan does at sea level with no restriction. so actual real world preformance is usually not as great as the manufacturer claims. i feel very skeptical that such a setup will really be stealthy and work well dan?

03-15-2011, 10:14 PM	#8 (permalink)
farmergiles Yahookan Join Date: Sep 2006 Location: Sick of the hatred and the lies Posts: 7,807 Thanks: 2,285 Thanked 3,750 Times in 2,554 Posts	It's not just the noise of the fan you have to worry about but noise of the air moving through the duct as well. Fans are usually more efficient pushing air rather than pulling (or vacuuming) it- having the fan in the attic pulling through 25' of 4" conduit will cause some air resistance. If the fan has to work harder it might make more noise. Maybe put the fan in the growspace, place it in a box filled with blankets or expanding foam (or any other sound insulating material). This should work better even if you go with the long duct to the attic. __________________ Cultivate a stoic calmness *Fuck the Monkeys* Every Kind of Vice

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