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booster fan vs inline exhaust fan

budsofmadison

budsofmadison

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so i got an ac infininity 6 inch booster fan blowing fresh air into my tent
i have a 6 inch spider farmer exhaust fan blowing air out
with both fans at full throttle, the 6 inch booster fan is blowing more air in my 3x3 tent then what the 6 inch spider farmer exhaust can take out does that make sense should the 6 inch exhaust fan be taking out more air then a 6 inch booster fan can blow in
 
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Nesta said:
Does your tent have a decent lung room? If so, get rid of the booster fan. I dont know your setup, but I run a couple tents and don't have a booster on any of them.
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well the tents are in my bedroom so i tried to make my bedroom a lung room i can get my room perfect but inside the tents it's always different , my tents are side by side and neither off them will say the same
 
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That's currently how I'm running except I got the exhaust fan outside the tent pulling air out....my booster fan is at max and my exhaust is at 3/4 or so it seems decent so far...I have a bend in the ducting for each to avoid light leak but have since blacked out my basement so I will probably straighten out my exhaust for max flow after my grow.....do a tear down and clean and redo everything a little better
 
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MDK said:
That's currently how I'm running except I got the exhaust fan outside the tent pulling air out....my booster fan is at max and my exhaust is at 3/4 or so it seems decent so far...I have a bend in the ducting for each to avoid light leak but have since blacked out my basement so I will probably straighten out my exhaust for max flow after my grow.....do a tear down and clean and redo everything a little better
Click to expand...
my booster fan is at 1/4 while the exhaust is at 3/4 i have thought about having everything outside my tent pull air from the tent and out through the filter
 
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I use this ACI 12"x20" filter rig on my intake. My room is dependent on fresh air and works with outside air, almost like an outdoor grow but it's indoors. I use the filter box because all kinds of dust and crap can come in thru there. I even have a rodent guard up in the duct just in case a critter thinks it could be a home or way into my home.

IMG_0338.JPG

I run a dual exhaust, both a 450CFM 8" and a 300CFM 6".
My goal is to have filtered fresh air come in but have an overwhelming amount of exhaust to pull air both from the fresh air intake even though it has the booster fan but also pull air from inside the house because that's a source of CO2. The negative pressure ensures a good and fast exchange to remove heat and humidity and also keeps all odor contained inside the room. I've got it to the point where there's so much negative pressure if the room door is not latched the exhaust can pull the door open.
Everything is speed and or timer controlled but the 8" exhaust is photosensor controlled only coming on with the lights to remove heat. The 6" exhaust is on 24/7. As it heats up outside I'll have to turn on a window unit AC to cool the warm air coming in and mitigate heat from lights to keep temps in the low 80s.

Winter growing is easier as the filter box becomes both fresh air and ac and I only need to run a single exhaust but for Summer growing I'm looking for as much negative pressure in the room as possible to get that heat and humidity out about as fast as it's created. CO2 and everything else becomes secondary to removing heat and humidity since they can ruin my crop
 
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not trying to hijack this thread but would fan placement make a difference?
in my case if i mounted the fans direct to the exhaust ports on the wall and ran the ducting from them would airflow increase?
didn't see a need to start a new thread as this might help budsofmadison also
 

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ineedmygranny said:
not trying to hijack this thread but would fan placement make a difference?
in my case if i mounted the fans direct to the exhaust ports on the wall and ran the ducting from them would airflow increase?
didn't see a need to start a new thread as this might help budsofmadison also
Click to expand...
i have my intake fan at the bottom of my tent i figure that gives me airflow down there i also think having the intake fan at the bottom and exhaust at the top means fresh air is being brought up
 
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ineedmygranny said:
not trying to hijack this thread but would fan placement make a difference?
in my case if i mounted the fans direct to the exhaust ports on the wall and ran the ducting from them would airflow increase?
didn't see a need to start a new thread as this might help budsofmadison also
Click to expand...
im far from an expert but to me seems the way u have it as soon as u bring in fresh air the exhaust is pulling it out
 
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ineedmygranny said:
no expert here at all but, are you saying a fan on the intake and no exhaust fan?
i'd think that you would have positive pressure to your room unless you had massive exhaust ports.
Click to expand...
i know your not talking to me but if you leave you vents open in your tent u do not need an intake fan just an exhaust fan
 
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budsofmadison said:
im far from an expert but to me seems the way u have it as soon as u bring in fresh air the exhaust is pulling it out
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could very well be true.
i have 1-4" passive intake , 1-8" passive intake and 1-4" with a fan all at the bottom and of course it exhausts from the top.
also have 2 -12" wall mounted hurricane fans moving shit tons of air and a tower fan on stand by.
i "think" the air gets mixed enough before it exhausts
 
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ineedmygranny said:
could very well be true.
i have 1-4" passive intake , 1-8" passive intake and 1-4" with a fan all at the bottom and of course it exhausts from the top.
also have 2 -12" wall mounted hurricane fans moving shit tons of air and a tower fan on stand by.
i "think" the air gets mixed enough before it exhausts
Click to expand...
im trading my tower fans in for some ac infinity clip on fans lol
 
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ineedmygranny said:
there was a HVAC tech on the other site, did he make it here?
don't remember the name
Click to expand...
Yes he did :D

ineedmygranny said:
not trying to hijack this thread but would fan placement make a difference?
in my case if i mounted the fans direct to the exhaust ports on the wall and ran the ducting from them would airflow increase?
didn't see a need to start a new thread as this might help budsofmadison also
Click to expand...
Yes the less duct you have the more air you will get out of the same blower. Also turns make a difference. So the fan in the back on your picture if you just flip that around and get rid of the u-bend of duct would give you more airflow. A tight radius 90 degree turn adds the equivalent of 5 feet of duct in terms or air resistance. So that u bend is like adding 10 feet to your duct.
 
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Scotty 420 said:
Yes he did :D


Yes the less duct you have the more air you will get out of the same blower. Also turns make a difference. So the fan in the back on your picture if you just flip that around and get rid of the u-bend of duct would give you more airflow. A tight radius 90 degree turn adds the equivalent of 5 feet of duct in terms or air resistance. So that u bend is like adding 10 feet to your duct.
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your awesome bud.
glad you made it here.
if i placed the fan on the hard mounted exhaust and placed the ducts str8 out with a 45 degree bend in opposite directions would that improve airflow?
 
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Aqua Man said:
Fan on the output up top and passive intake from the flaps on the bottom.
Click to expand...
That's how I have mine set up. The fan is outside the tent, on the top. The intake is at the bottom at the opposite side of the tent, so there's a crossflow of air from corner to corner.

I also have a sensor on the output to measure temperature and humidity. I added it out of curiosity. Its readings are usually close to what the sensors inside the tent are reporting.
 
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Rootsruler said:
Why do you need a booster fan? I run the T6 in my 5 x 5 and it exchanges plenty of air.

I have the exhaust fan mounted on the roof of the tent sucking air out while the bottom vents flow air into the tent and up through the canopy.

In case you don't know you want 3 air exchanges a minute minimum in your tent. Mine is a 5' x 5' x 6.5'. That gives me 162.5 cubic feet of space. I have the same ACI T6 you have. It maxes at 402 cfm. 162.5 x 3 = 487.5 cfm. I need a bigger fan. I'm looking at the T8 as a replacement. It puts out 807 cfm.
Click to expand...
I started with just an 6” in-line booster fan in both tent zones. (Zone 2 & 3 share air)

I found humidity and temp changes needed a better balance than just the draw of the top fans.

When I got the T6 with controller it was a game changer but still has humidity vs temp issues. Especially at lights out. Putting the old boosters in the bottom vent holes solved that but manually.

The hole, at 6”, is enough to leave it off some days. Others it’s enough to leave on low. Once in a while, like the crazy hot/cold weeks we just had, I have to turn them way up.

I do this because it saves wear and tear on the main fans and it’s cheaper than buying or running other equipment in the same space.

If I open the basement window with the bottom booster fan on it gets me to 50% RH fast. Without driving the temp down to 18*c. Booster pulls in but main fan is off with just currant pushing through.

Probably doing it all wrong. 🤣
 
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budsofmadison said:
the ac fan is good in my 4x4 so u think a 6 inch exhaust would be too much for a 3 x3
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My T6 is great in a 3x3. Set to never go higher than 6 and step up smoothly rather than full blast.

I’ve had to replace furnace fans for myself and others so usually get bigger so it works less for same results. Like over engineering. You don’t need to run it full if half is good but if you need more you have it. It’s only a few $$ more for the next size so I’m hoping to future proof my purchase.
 
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ineedmygranny said:
not trying to hijack this thread but would fan placement make a difference?
in my case if i mounted the fans direct to the exhaust ports on the wall and ran the ducting from them would airflow increase?
didn't see a need to start a new thread as this might help budsofmadison also
Click to expand...
I put my fan outside to pull air rather than push. Also little less heat inside helps. More room for light to go up too.
 
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