intake holes? - Micro Grows - International Cannagraphic Magazine Forums

munkie · 10-23-2006, 01:42 AM

Hey all, Im getting my cab tomorrow 2.6wx1.5dx3.5h and Im planning on buying a 100mm RVK fan which is 4" in diameter. Going by the 2x larger intake than exhaust, can I just drill 2, 4" holes and fit them with an S shaped PVC pipe? Did a search but couldnt find anything specific. Thanks!

10-23-2006, 01:44 AM

yea that what i did

mtnjohn · 10-23-2006, 03:09 AM

2x larger intake??...why??

bounty29 · 10-23-2006, 03:14 AM

That's a general rule of thumb.

I've got two 4" fans blowing out of the top of my cabinet, which is a total of about 25 sq in, and I've got two 5"x5" squares at the bottom of the cabinet. So far it's working out great.

You can have less intake, but it will put more stress on your fan, decrease your airflow, and result in higher temperatures.

mtnjohn · 10-23-2006, 05:16 AM

my fans have been running for three years and they are doing just great.
the temps in my cab are usually about 5f over ambient room temp w the light on.
(150hps)i have a 2 inch intake and a 4 inch exhaust. dont get me wrong i'm not knoking more intake , but i wanted to create a more negative pressure atmosphere for my cab.my intake will hold up a piece of card board -no prob. it will also hold my door shut which in turn helps with getting a good tight seal.. so less chance of a light leak.
who knows, maybe i should have more intake , i just dont have room tho.
oh yea my fans are two 80 cfm 12v comp fans btw

oh well, its all good to me

ECUG · 10-24-2006, 01:20 AM

Gotta love mtnjohn, props man!!!! Munkie, why not start out with one hole, check lights on/off temps, and go from there. If one 4" hole does the trick, (negative pressure and close to ambient temps) stick with it if not experiment. I personally use 2" holes on either end of my box as intake, and a 4" fan as exhaust. It makes me feel like the fresh air is being spread more even??

10-24-2006, 01:25 AM

i have 4 2 in holes..2 on each side...and if i need more i can add them to the sides of the tub...but i do find that it gets an even amount of new air all over LOL...im just guessiong on that one i have no idea how to check it but common logic would think it would be ok

bounty29 · 10-24-2006, 02:02 AM

mtnjohn, if it works out that's great, but since you're saying it'll hold up a piece of cardboard it just shows that a lot of air is being pulled through that small space, which makes your fan have to work harder. The area of a 4" hole is about 12sq in, where the area of a 2" hole is only 3.14sq in (Which is why two 2" holes does not equal one 4", as some believe.) I bet if you were able to increase the intake to at least the same as the exhaust, you might be able to keep the temps in the cab the same as ambient.

mtnjohn · 10-24-2006, 03:40 AM

hey bounty29, hows it going? you are probably right and i may possibly size up to a
3' pvc intake at some point....but that will be on my new cab sometime in the near future, i hope. micro grows are so much fun
also glad we have a micro forum with such a fine group of peeps , eh?
..................mj

bongasaurus · 10-24-2006, 07:10 AM

looks awesome mtnjohn. love the avatar too.

if you dont ming me asking, where did you get those fans? ive got a lil cab with a comp fan exhaust and 3 2inch intake holes but it still gets pretty hot in there. how are they for sound?

10-23-2006, 01:42 AM	#1
munkie Member Join Date: Sep 2006 Posts: 84	intake holes? Hey all, Im getting my cab tomorrow 2.6wx1.5dx3.5h and Im planning on buying a 100mm RVK fan which is 4" in diameter. Going by the 2x larger intake than exhaust, can I just drill 2, 4" holes and fit them with an S shaped PVC pipe? Did a search but couldnt find anything specific. Thanks! __________________ First grow
	Quote

10-23-2006, 01:44 AM	#2
Guest Guest Posts: n/a	yea that what i did
	Quote

10-23-2006, 03:09 AM	#3
mtnjohn Banned Join Date: Jan 2005 Posts: 1,365	2x larger intake??...why??
	Quote

10-23-2006, 03:14 AM	#4
bounty29 Custom User Title Join Date: Jun 2006 Posts: 3,252	That's a general rule of thumb. I've got two 4" fans blowing out of the top of my cabinet, which is a total of about 25 sq in, and I've got two 5"x5" squares at the bottom of the cabinet. So far it's working out great. You can have less intake, but it will put more stress on your fan, decrease your airflow, and result in higher temperatures.
	Quote

10-23-2006, 05:16 AM	#5
mtnjohn Banned Join Date: Jan 2005 Posts: 1,365	my fans have been running for three years and they are doing just great. the temps in my cab are usually about 5f over ambient room temp w the light on. (150hps)i have a 2 inch intake and a 4 inch exhaust. dont get me wrong i'm not knoking more intake , but i wanted to create a more negative pressure atmosphere for my cab.my intake will hold up a piece of card board -no prob. it will also hold my door shut which in turn helps with getting a good tight seal.. so less chance of a light leak. who knows, maybe i should have more intake , i just dont have room tho. oh yea my fans are two 80 cfm 12v comp fans btw oh well, its all good to me Last edited by mtnjohn; 10-23-2006 at 05:19 AM..
	Quote

10-24-2006, 01:20 AM	#6
ECUG Novice grower. Join Date: Aug 2006 Location: NE Posts: 200	Gotta love mtnjohn, props man!!!! Munkie, why not start out with one hole, check lights on/off temps, and go from there. If one 4" hole does the trick, (negative pressure and close to ambient temps) stick with it if not experiment. I personally use 2" holes on either end of my box as intake, and a 4" fan as exhaust. It makes me feel like the fresh air is being spread more even??
	Quote

10-24-2006, 01:25 AM	#7
Guest Guest Posts: n/a	i have 4 2 in holes..2 on each side...and if i need more i can add them to the sides of the tub...but i do find that it gets an even amount of new air all over LOL...im just guessiong on that one i have no idea how to check it but common logic would think it would be ok
	Quote

10-24-2006, 02:02 AM	#8
bounty29 Custom User Title Join Date: Jun 2006 Posts: 3,252	mtnjohn, if it works out that's great, but since you're saying it'll hold up a piece of cardboard it just shows that a lot of air is being pulled through that small space, which makes your fan have to work harder. The area of a 4" hole is about 12sq in, where the area of a 2" hole is only 3.14sq in (Which is why two 2" holes does not equal one 4", as some believe.) I bet if you were able to increase the intake to at least the same as the exhaust, you might be able to keep the temps in the cab the same as ambient.
	Quote

10-24-2006, 03:40 AM	#9
mtnjohn Banned Join Date: Jan 2005 Posts: 1,365	hey bounty29, hows it going? you are probably right and i may possibly size up to a 3' pvc intake at some point....but that will be on my new cab sometime in the near future, i hope. micro grows are so much fun also glad we have a micro forum with such a fine group of peeps , eh? ..................mj
	Quote

10-24-2006, 07:10 AM	#10
bongasaurus king of the dinosaurs Join Date: Feb 2006 Location: canadia. land of the free Posts: 1,114	looks awesome mtnjohn. love the avatar too. if you dont ming me asking, where did you get those fans? ive got a lil cab with a comp fan exhaust and 3 2inch intake holes but it still gets pretty hot in there. how are they for sound? __________________ word og another line in the field of time i got a window washers eye for an untuckable sky Let it grow, let it grow, Let it blossom, let it flow. In the sun and in the snow
	Quote