ventilation help please from experience

[semajkroy]

I'm having a hell of a time trying to figure out my ventilations system
I understand negative pressure and that in most situation a passive intake is a better choice .. With that being said I don't know if I should plan on using a fan on my intake as well as exhaust .ok so my setup
3.5'x2'x5' (LWH) custom wooden box
Ipower 400 watt dimmable with cooltube
4" sunleaves wind tunnel inline fan (exhaust) (200cfm)
2 to 3 plants SCROG (if it matters)
oscilating desk fan just above the canopy
soil grow
ok so there's my equipment minus the smoke detector and temp humidity gauge stuff like that
everything is setup so I'm not looking for buy a bigger this or different that . That is what I'm working with
now to my question(s)
this will all be in a sliding door closet which is why is only two feet deep the exhaust will go as such
carbon filter--light--1ft ducting---fan--ducting to ceiling
so I will be trying to scrub the air and cool the light on the same exhaust fan
the part in having problems with is my intake
my intake will be a hole in the wall with a foot or two ductwork connecting the hole to the box drawing from the room the closet is in ambient tempts are 73 74
I understand that if I was using a passive intake I would need ether one 8" or two 4" i would have to go with the two 4" so I don't have a huge 8" hole in my bedroom wall
so setup A would go something like this
• 4" hole in wall ---Y connector or splitter of some sort -- 2 4" hole in the box
my concerns with this is there would need to be a bend or two to make this fit will there still be enough airflow with the splitter and bend s
• setup B 4" hole in wall - duct booster fan (100 cfm)-- ductwork -- one 4" hole in the box with a 90"degree or hood on the inside to block light from coming in the box
keep in mind that there will only be maybe 2' at most ductwork between the hole in the wall and the box
my concerns with this is negative pressure
please if you have EXPERIENCE with something similar can you lend me a suggestion on which way to go
thanks in advance

 

[JSB99]

I would set your flow as follows based on lots of research:

filter > fan > cool tube > exhaust

You'll lose a lot of CFM with the filter and I'm not sure adding an intake fan would create enough positive pressure to help the exhaust. I've always read that passive is best. You might want to consider adding a duct booster fan after the cool tube, but you may have better luck with a 6" booster fan and 6" ducting rather than 4". You would just have to get a 4" to 6" reducer to go from your tube to your booster fan.

If you can mount your sunleaves fan directly to your cool tube that might help as well.

You may be able to get away with a single 4" hole for the intake, but have it at the furthest point away from your filter so the air has to travel across your plants to get to it.

 

[semajkroy]

I would set your flow as follows based on lots of research:

filter > fan > cool tube > exhaust

You'll lose a lot of CFM with the filter and I'm not sure adding an intake fan would create enough positive pressure to help the exhaust. I've always read that passive is best. You might want to consider adding a duct booster fan after the cool tube, but you may have better luck with a 6" booster fan and 6" ducting rather than 4". You would just have to get a 4" to 6" reducer to go from your tube to your booster fan.

If you can mount your sunleaves fan directly to your cool tube that might help as well.

You may be able to get away with a single 4" hole for the intake, but have it at the furthest point away from your filter so the air has to travel across your plants to get to it.

so your saying to push air through the light rather than pull it I've always read pull mot push ? Also space wont allow me to attach the fan to the light it will be on top of the box in its own box to quiten it I didn't think that foot of duct from the tube to the fan would make that much difference

 

[JSB99]

Also, you may want to consider a light mover to cover the whole area.

 

[JSB99]

so your saying to push air through the light rather than pull it I've always read pull mot push ?

Pulling hot air through your fan supposedly reduces the life of your fan.

 

[JSB99]

And, if there are any leaks in your ducting, it gets blown back into the grow area so there's less chance of smelly air being exhausted.

 

[semajkroy]

Pulling hot air through your fan supposedly reduces the life of your fan.

fans on a warranty lol not so worried bout that and light movers i don't know what that is unless I just know it as a different name

 

[JSB99]

fans on a warranty lol not so worried bout that and light movers i don't know what that is unless I just know it as a different name

It'll work either way and most people don't worry too much about this. The heat on the fan is the only real argument I've heard about having the fan pre-light.

 

[semajkroy]

And, if there are any leaks in your ducting, it gets blown back into the grow area so there's less chance of smelly air being exhausted.

ibwas going to use insulated ducting this should solve that problem right ? Also you now have my thinking about using 6" from the fan to the celing would this make a noticeable difference vs the 4"

 

[JSB99]

ibwas going to use insulated ducting this should solve that problem right ? Also you now have my thinking about using 6" from the fan to the celing would this make a noticeable difference vs the 4"

Very noticeable. But, get one with a speed controller or buy one. They're only $20. That way you only need to run your fan on high when needed.

There are plenty of inexpensive 6" inline fans on ebay and amazon.

 

[JSB99]

And yes, insulated dusting should solve that issue.

 

[JSB99]

Look at this fan...
http://www.amazon.com/Hurricane-Fan...&qid=1422487902&sr=8-6&keywords=6"+inline+fan

and this controller...
http://www.amazon.com/VenTech-VTSPE...3&sr=8-2&keywords=inline+fan+speed+controller

 

[semajkroy]

Very noticeable. But, get one with a speed controller or buy one. They're only $20. That way you only need to run your fan on high when needed.

There are plenty of inexpensive 6" inline fans on ebay and amazon.

i think we misunderstood each other i meant just using a 4 to 6? Reducer backwards to use a 4" fan with 6 " ductwork

 

[JSB99]

i think we misunderstood each other i meant just using a 4 to 6? Reducer backwards to use a 4" fan with 6 " ductwork

I see. Yes, that should help.

Scratch that. I'm not sure it would make a difference.

 

[JSB99]

Unless, like I said, you use the inline fan before your tube and then a booster after

 

[semajkroy]

maybe someone else can weigh in on that part ..and thanks for the help and fan suggestion ill look into a 6" again but I've went through It before and for noise level reasons I settled on the 4" I know I could get a speed controller to help with noise but I don't understand the point of buying a bigger fan just to dial it down ?
edit: Also I only need to circulate 60 ish cfm adding in the filter I figured 200 cfm out of a 4" would be plenty

 

[JSB99]

maybe someone else can weigh in on that part ..and thanks for the help and fan suggestion ill look into a 6" again but I've went through It before and for noise level reasons I settled on the 4" I know I could get a speed controller to help with noise but I don't understand the point of buying a bigger fan just to dial it down ?

A bigger fan and a controller will give you the option to run at higher speeds when needed. There are a lot of times when you need to cool your light more than usual. Better to have more available than to not have enough. You lose a lot of cfm with the filter. It comes down to your needs and money, but fighting heat sucks IMHO.

I'm sure others will chime in.

Good luck.

 

[semajkroy]

A bigger fan and a controller will give you the option to run at higher speeds when needed. There are a lot of times when you need to cool your light more than usual. Better to have more available than to not have enough. You lose a lot of cfm with the filter. It comes down to your needs and money, but fighting heat sucks IMHO.

I'm sure others will chime in.

Good luck.

thanks you do make an inarguable point i was just trying to keep it simple and stealthy as possible ..seeing as the cooltube is 6" maybe I should just go with a 6" fan ill look into it some more but that would mean ife have to send one back and wait on another if I can avoid this IDE like too

 

[semajkroy]

A bigger fan and a controller will give you the option to run at higher speeds when needed. There are a lot of times when you need to cool your light more than usual. Better to have more available than to not have enough. You lose a lot of cfm with the filter. It comes down to your needs and money, but fighting heat sucks IMHO.

I'm sure others will chime in.

Good luck.

also if i was to use a 6" fan could i use a 4-6 reducer backwards on thr intake hole in the wall to keep my intake hole from my room to my closet 4" without causing problems or does that defeat the purpose

 

[JSB99]

thanks you do make an inarguable point i was just trying to keep it simple and stealthy as possible ..seeing as the cooltube is 6" maybe I should just go with a 6" fan ill look into it some more but that would mean ife have to send one back and wait on another if I can avoid this IDE like too

I thought you have a 4" cool tube. Don't even know if they make those.

Yes, you should use a 6" fan, filter, and ducting.

There are ways to reduce the noise from an inline fan. Having insulated ducting is one of them. You can also get a muffler. Not very expensive. But running the fan on low (which is probably what you'll be doing most of the time) isn't going to be that loud. May even be equivalent or less than the 4" fan on high.