intake fan for 4" circular opening

Chris02011

Active Member
Does anyone know what intake fan would fit my grow box that has a 4" circular opening? Im using CFL's so i dont need anything powerful or expensive. Thanks!!
 

MrDank007

Well-Known Member
As long as nothing is obstructing the fans airflow, you can wire a 120 mm PC fan to a 12V cell phone charger. Cheap, easy and small.
 

BigBudE

Well-Known Member
Mr.Dank007 is right. What are the measurements? I would have one around the top and another one for intake around the bottom on the side.
BigBudE
 

Chris02011

Active Member
the tent is 3 X 3 X 6. Im more concerned with finding a fan that will fit the 4inch opening. Will the 120mm fan fit a circular opening?
 

BigBudE

Well-Known Member
For something that size i would get something bigger than a computer fan. you can go to a lowes or a home depot and get a 4" inline vent fan (i think they might be pre wired but cant remember) for around $20- 30$ and there already round. You can also buy either an auto temp or speed adjuster for those to. If you get one with a good CFM you might be able to bypass the intake fan.
BigBudE
 

MrDank007

Well-Known Member
The PC fan is circular but the case is square. The higher end ones claim to push 100 CFM, but I can tell you they lack a lot of umph and any screens, light traps, or filters will dramatically reduce their pull.

You have 54 cubic feet, so you would probably need to double up, but the PC fans are really for smaller areas than your tent. BigBudE is probably right that you might just want to use a good inline fan for that size space. You probably need something in the ballpark of your exhaust as well.
 

djruiner

Well-Known Member
i just got 2 4 inch round cpu fans off ebay...$5 a peice...mounted them inside the ends of 2 dryer vents for my grow box....works great...when i put my hand over the intake...it feels like a vaccum hose...keeps my temps around 81-85f now...was running up to 110-115f....the sellers name on ebay is "the fan van"...he should ahve about any type of fan you would need for dirt cheap
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St3ve

Member
You know, if it were me I would just mount the fans right up on top of the holes blowing OUT of the tent. For two reasons: Those fans are meant to PULL air, not push it through your duct. Secondly, the hottest air is going to be in the TOP of the tent (which is why the holes are there) not in the middle where you have placed the fans.

So aside from getting rid of that dryer duct, it will actually do a better job. Not to mention the fans will run faster from having less resistance. If light escaping is an issue, then at least shorten your dryer duct and point it UP towards the ceiling.
 

djruiner

Well-Known Member
You know, if it were me I would just mount the fans right up on top of the holes blowing OUT of the tent. For two reasons: Those fans are meant to PULL air, not push it through your duct. Secondly, the hottest air is going to be in the TOP of the tent (which is why the holes are there) not in the middle where you have placed the fans.

So aside from getting rid of that dryer duct, it will actually do a better job. Not to mention the fans will run faster from having less resistance. If light escaping is an issue, then at least shorten your dryer duct and point it UP towards the ceiling.
those are flex dryer ducts...that was right after i mounted it...i have moved them around since then to better fit in with the hoods...and if my temps are in the low 80's...why would i change anything?and if you simply turn the fan around...it pushes the air..same as it pulls...and since i have no light leaks...air is flowing great...low temps..with another fan on the inside...it seems it works just fine...why fix what aint broke?
 

St3ve

Member
Just throwin' my 2cents in is all. :) Exhaust fans are meant to pull air, so they do it more efficiently than they push. Have you ever noticed that your PC fans that are in your computer are mostly sucking out of the computer? A fan can "pull" air up to 4 times more than it can "push it. As an experiment, leave one fan the way it is, and hook up the other fan as I mentioned and test it for yourself. If I'm wrong just come back here and eSlap me. :)

I just try to get the most out of all my equipment so I'm always looking for ways to make things work better. If you're happy, then I'm happy.
 
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