Static Pressure Problems With Inline Fans

  • Thread starter Dreamingtree
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Dreamingtree

Dreamingtree

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Static pressure for dummies like me
No ducts, filters, or obstructions = lower static pressure

Ductwork, bends, length, carbon filter, and light goods = high static pressure

Axial fans used for lower static pressure

Centrifugal fans used for high static pressure, ductwork, carbon filter, etc.

Ive been doing research and trying to find people who have had similar interests problems with inline fans not pulling hard enough or fast enough to be effective at extracting enough air from my grow tent to keep temps down.
I bough a couple of those little 30$ inline booster fans 175 com from Home Depot to use as extraction fans. One 6 inch little duct booster fan without any ducting or filter like this......

310BE5AD 2A07 4DBB ADB7 01669BAC7A32
BB7DE375 5ECD 4E92 819D 93BB689C7C69

.....does well enough by itself to move enough air to keep the temperature down. Then I hook up a tiny bit of duct to it and a carbon filter. Trash. My temperature shoots up to 86 Fahrenheit from 78.
I have looked around online before deciding and came to the conclusion that a fan like this.....
367589D3 E85C 452E 9597 A2D48208EFEA

Centrifugal inline fan

.... will be able to do a better job moving air against static pressure caused by ductwork, bends in ducting, carbon filters, light hoods, or anything else that causes higher static pressure in the ventilation system than this......
4682FCAA CBF5 450C BDB5 62EEE6145607

Axial in-line fan

Or one of those silver ones that cost 30 bucks at the hardware store.
The axial fan is good for moving air if there is no duct work filter and low static pressure. The centrifugal fan is much better for moving air through ducting carbon filters and other obstructions. Similar to having more torque or more horsepower.



Is this conclusion accurate? Please answer if i am correct in my conclusion. Thank you.
Check out my grow journal
 
Dan789

Dan789

2,951
263
Get yourself one of the better axial fans, I’m using a max fan 6” to exhaust three tents through a carbon scrubber, length of ducting and makeup air supply into tents of course are all factors. The duct fans you’ve shown are also called booster fans, not too suited as you’ve found out. The axial fans are also quieter and are speed control suitable which can be important.
 
Dreamingtree

Dreamingtree

23
3
Get yourself one of the better axial fans, I’m using a max fan 6” to exhaust three tents through a carbon scrubber, length of ducting and makeup air supply into tents of course are all factors. The duct fans you’ve shown are also called booster fans, not too suited as you’ve found out. The axial fans are also quieter and are speed control suitable which can be important.
So one of the better axial fans would have enough power to run through a carbon filter and 2 feet of duct? And much more effectively cool my tent?

Check out my grow journal. Just switched to flower day 2
 
Dan789

Dan789

2,951
263
This is what I did, one fan, three tents, one phatt carbon filter. Exhaust and odor control. (Ducting for third tent added after this shot, from prior post).
PS, improvised junction, cardboard box, glue gun, aluminum flanges, price was right and works fine...
 
Dreamingtree

Dreamingtree

23
3
892199B6 E97C 4BD2 AD43 11620F05F2B1
7B8150CE 1162 4034 AE0C 5A7B7BE4E3BD
Thanks dan. You’ve answered a couple of my questions so far. I just switched to flower. Check these black indica fems out. I topped them twice. They’re from crop king seeds. They’re bushy as hell. I’ll post the new fan setup when the one I just ordered gets here.
 
Dirtbag

Dirtbag

Supporter
7,805
313
You initial observation is correct. Use a centrifugal fan designed to overcome static pressure. never cheap out on the fan used for smell scrubbing and extraction. preferably I like to use one that's one size bigger than necessary and put a speed controller on it and run it slower. You get better odor removal that way. Can-fans are my personal favourite brand, I use a 10" Q-max fan built by Can-fan that is so quiet on its built in low setting, you cant even hear it running when it's on. Mind you that's for an 8x8x9'space. The circulation fans and ballasts make way more noise than it does and it moves air fast through the carbon filter and intake filter.
 
Dreamingtree

Dreamingtree

23
3
8F9ACCC4 0739 4925 A2BB 9514B43877D7
You initial observation is correct. Use a centrifugal fan designed to overcome static pressure. never cheap out on the fan used for smell scrubbing and extraction. preferably I like to use one that's one size bigger than necessary and put a speed controller on it and run it slower. You get better odor removal that way. Can-fans are my personal favourite brand, I use a 10" Q-max fan built by Can-fan that is so quiet on its built in low setting, you cant even hear it running when it's on. Mind you that's for an 8x8x9'space. The circulation fans and ballasts make way more noise than it does and it moves air fast through the carbon filter and intake filter.
Thanks dirtbag I ordered this fan. It’s a Vivosun 6 inch 400 + cam with a speed control switch. If this doesn’t work I’m doing something wrong. I’ll post a picture of how I set it up when it gets here.
Thanks
 
Dreamingtree

Dreamingtree

23
3
487BF636 5CA3 442E 85F7 B8166F4C36E2
This is what I did, one fan, three tents, one phatt carbon filter. Exhaust and odor control. (Ducting for third tent added after this shot, from prior post).
PS, improvised junction, cardboard box, glue gun, aluminum flanges, price was right and works fine...
You have tents, I have a tent, extraction is similar. How do you have your air intake set up? Is it passive or do you use fans? I’m curious how you have yours because on my tent the passive air vents aren’t light proof. They have Velcro covers but no air gets through those. How do you lightproof your intake? I put silver baking trays cut in half over mine to try to keep light from getting in
 
Dan789

Dan789

2,951
263
View attachment 858278
You have tents, I have a tent, extraction is similar. How do you have your air intake set up? Is it passive or do you use fans? I’m curious how you have yours because on my tent the passive air vents aren’t light proof. They have Velcro covers but no air gets through those. How do you lightproof your intake? I put silver baking trays cut in half over mine to try to keep light from getting in
I simply placed about one foot of 6” flexible ducting through into the tent with cheese cloth hot glued to the end which allows air to enter and prevents most of the light, with that 90 degree bend, two per tent or so. Only one fan, sucking out of the tents and then blowing out through the filter, see earlier shots. This has been my “MO” for the last few years and works fine.
 
Dreamingtree

Dreamingtree

23
3
I simply placed about one foot of 6” flexible ducting through into the tent with cheese cloth hot glued to the end which allows air to enter and prevents most of the light, with that 90 degree bend, two per tent or so. Only one fan, sucking out of the tents and then blowing out through the filter, see earlier shots. This has been my “MO” for the last few years and works fine.
I’m gonna do the same. Thank you
 
chemistry

chemistry

3,735
263
You need to build a light trap, S shaped with a flat/matt black coating (non reflective) or painted on the inside, light can only travel in a straight line, or it's reflected.
 

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