Static Pressure Problems With Inline Fans

Dreamingtree · Feb 23, 2019

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......

.....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.....

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......

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 · Feb 23, 2019

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 · Feb 23, 2019

Dan789 said:
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

1diesel1 · Feb 23, 2019

Dreamingtree said:
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

Yes, much more efficient if your tuning any corners make sure you hardline your duct work otherwise your defeating the purpose of efficiency.

Dreamingtree · Feb 23, 2019

1diesel1 said:
Yes, much more efficient if your tuning any corners make sure you hardline your duct work otherwise your defeating the purpose of efficiency.

Got it

Dan789 · Feb 23, 2019

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 · Feb 23, 2019

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 · Feb 23, 2019

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 · Feb 24, 2019

Dirtbag said:
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 · Feb 24, 2019

Dan789 said:
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 · Feb 24, 2019

Dreamingtree said:
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 · Feb 24, 2019

Dan789 said:
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 · Feb 24, 2019

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.

Static Pressure Problems With Inline Fans

Static Pressure Problems With Inline Fans

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