4" carbon filter 6" fan

H

Hushgon

Member
Hello!

I have a question about fans, ducts and reducers.

Currently i have:
filter 4" -> 4" duct -> 4"/6" "enlarger" -> 6" fan

What i wanna know is do i get an improved airflow for my fan by replacing the duct with a 6" and running the reducer first?

Like this:
filter 4" -> 4"/6" enlarger -> 6" duct -> 6" fan

I have a small problem with heat (82f with a 125w cfl), the plants will survive but a few degrees wouldn't hurt them.

Anyone have a good ventilation knowledge or any links where i can find out the answer!

/Thanks!
 
vostok

vostok

Well-Known Member
the deal is to get a 100% air replacement every 3- 5 minutes

you have made no mention of the size of your grow room

a 6 inch filter on a 6 inch fan

sounds easy nor to far fetched

but not with you?

good luck
 
TacoMac

TacoMac

Well-Known Member
The power of the fan decides a lot as well. If the fan doesn't generate enough flow, putting it on a larger duct will make matters worse, not better.

It take a lot more air to play a Tuba than it does a Trumpet.

You need to figure out how large the area you're growing in is, how much duct work you're actually using, then look at the CFM rating of the fan and crunch some numbers to figure out what you need to do.
 
H

Hushgon

Member
Oh sorry,

The tent is 40x40x120 cm ~16"x~16"x~47"
The fan is a 280 m3/h (165 cfm)
Carbon filter is rated for optimal 160 m3/h(94 cfm) and max 240 m3/h (141 cfm)
Reason for the small filter is the small growspace, a 6" filter would never be able to fit in the tent.

I run the fan at around 50%-ish to get lower sound but the same performance as a 4" fan

If i only replace the air every 3-5 min the heat in the tent will be very high.
(So 0.4*0.4*1.2 = 0.192 m3)
140/0.192 = 729 air changes per hour or 12.15 times a minute

But this is with 0 air resistance which isn't the case

I have looked a lot but i can't find the air resistance for the carbon filter.

This is the exact fan i have
ventilation-system com/item/tt-125/#parameters (i hope this is okay)
Here you can even input the air resistance and get the performance at a specific preasure but as i can't calculate the air preasure i have no idea what the fan is acually running at. But unfortunatly 50% is all i can run as i hear the fan from my bed and that is why i asked if the bigger duct helps.

Thanks
 
Wilderb

Wilderb

Well-Known Member
IF you are using your fan for BOTH cooling and smell extraction, you are going to have a much higher exchange rate than that, depending on your incoming temp. That's a pretty small space.
Make sure it's pulling air from the bottom to the top.
 
H

Hushgon

Member
Wilderb said:
IF you are using your fan for BOTH cooling and smell extraction, you are going to have a much higher exchange rate than that, depending on your incoming temp. That's a pretty small space.
Make sure it's pulling air from the bottom to the top.
Click to expand...
Yeah i have two fans but unfortunatly only one filter,
I am pulling air in from the lower left and sucking it out in the upper right corner so diagonally.

I have pretty much tried everything except the bigger duct so that is why i asked hoping that the more experianced people like you guys could help!

Thanks
 
Wilderb

Wilderb

Well-Known Member
Hushgon said:
No unfortunately not, but here is a drawing of it!

Did that make it a bit more clear? Its only 40cm deep so it pretty much hangs in the middle.
Click to expand...
Okay I think I am getting it. What are your temps outside tent?
How many passive air vents do you have on bottom? The reason I ask is you want your carbon scrubber on the opposite side of your intake, whenever possible. You want to create a vacuum that draws the air in from the bottom and allow that air to be heated and removed. I guess in your case that could be difficult.
When I ran a smaller filter with a bigger fan, I found it worked best to run filter-reducer-ducting-fan.
But you're talking really small space and I'm guessing that light makes some heat.
It may be you have to find a way to cool you incoming air.
Perhaps somebody with more experience with smaller grow areas could help.


@whitebb2727 has a pretty impressive set up. Perhaps he can help?
WE
 
H

Hushgon

Member
Wilderb said:
Okay I think I am getting it. (snip)

@whitebb2727 has a pretty impressive set up. Perhaps he can help?
WE
Click to expand...
I have a big square that is just an intake hole and that is totally free, and one of those holes you can close around a vent that is a bit open to allow for more air, maybe i can reduce the neg. preasure inte tent a bit, as long as it doesn't smell it's alright.

The temp for intake is between 22-24 and cooling it is impractical / almost impossible as ACs are really expensive / uncommon here.
I guess if i can earn even 1 cfm from the better ducting it would be worth the work so i guess running the reducer first is my next step as i have all the parts already.
The lamp is the only heat source in the tent so it accounts for all the heat (delta of 4-6 degrees).

Thanks for all the help!
Any more ideas are always welcome
 
whitebb2727

whitebb2727

Well-Known Member
The filter will fail. It is too small for the fan.

This is a 2 x 4 x 6 cab. I just replaced that 4 inch filter with a 8 inch filter. It is for 8 inch duct and 12 inches wide by 22 inches long. Its huge.IMG_20160712_202651457_HDR.jpg
 
whitebb2727

whitebb2727

Well-Known Member
They also make shorty 6 inch filters.

Are you exhausting the heat outside the house? That is a must. If you are just blowing heat back into the room or house its hurting you cooling capacity.
 
H

Hushgon

Member
Thanks for the help @whitebb2727 !

I vent the air into the room but the room is pretty big and the tent should suck the air from the ground, i have a termometer outside of the intake and the temp should be fine, but i'll try to work on an alternate solution!


I looked around and i found a filter that has a max cap of 360 m3/h and optimal 240 m3/h which is around the rating i run the fan i have at, the filter should fit into the growspace, just builds 5cm width and 5cm height also 125mm fitting so no reducers needed.

Before i pull the trigger on it do you think that would help significantly?
 
Antman15

Antman15

Well-Known Member
TacoMac said:
Yep. I already have tickets. I'm taking my 15 year old daughter to her first rock concert to see them at the Fox Theatre here in Atlanta on May 3rd.

We're in the 6th row right in front of big Ben.
Click to expand...
Awesome!!!. I'm hoping to get tickets tonight after paychecks. Still paying off 3 PJ shows from last year, including both Wrigleys. I spent a little too much...oh well. Have fun brother.
 
sunandsky

sunandsky

Well-Known Member
whitebb2727 said:
They new bigger filter.
View attachment 3907372
The old one.
View attachment 3907373
Click to expand...
Hey what size of fan do you have for that 8 inch? I have a 4 inch filter now that really doesn't do that much, was looking to replace it with an 8 inch. I have a 190cfm 4 inch fan in a 3x3x7 tent. I've read conflicting ideas over fan speed. some say if you set the fan too low it won't do it's job, others say if it's too high it won't work. I've been flying at about 60% fan speed for my 4 inch filter. I can keep my living areas mostly smell free, but the bedroom i have the tent in is pretty stinky still. Need a fix for this !
 
whitebb2727

whitebb2727

Well-Known Member
sunandsky said:
Hey what size of fan do you have for that 8 inch? I have a 4 inch filter now that really doesn't do that much, was looking to replace it with an 8 inch. I have a 190cfm 4 inch fan in a 3x3x7 tent. I've read conflicting ideas over fan speed. some say if you set the fan too low it won't do it's job, others say if it's too high it won't work. I've been flying at about 60% fan speed for my 4 inch filter. I can keep my living areas mostly smell free, but the bedroom i have the tent in is pretty stinky still. Need a fix for this !
Click to expand...
4 inch 190cfm fan for 8 inch filter. You can never run a fan too slow. The slower the air moves over the carbon the longer it has to filter.
DSC01480.JPG DSC01478.JPG
Here you can see the adapter.
 
sunandsky

sunandsky

Well-Known Member
whitebb2727 said:
4 inch fan for 8 inch filter. You can never run a fan too slow. The slower the air moves over the carbon the longer it has to filter.
View attachment 3917235 View attachment 3917236
Click to expand...
hmm okay thanks Al. I'm thinking maybe I should just exhaust the smell out my window. I'm a medical patient so it's legal. I just don't want to draw attention to myself. Never know, some landlords just use a bullshit excuse to kick you out if they feel like it.
 
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