8 inch inline fan for 2x2x5 cabinet

[haupiapie]

Total noob here. I'm running two 200w California Lightworks led units in a 2x2x5 cabinet and I have to crank down the room AC at 65 in order to get temps below 80 degrees in the cabinet. I use a 6 inch 435 cfm inline with filter along with 2 clipon fans. Would replacing the 6 inch inline fan with an 8 inch be any better?

 

[TreehouseJ]

Do you have a passive intake vent? 435 / (2x2x5) = 21.75.

You are exchanging the air in your tent 21.75 times per minute, providing that your extractor fan has a passive intake to pull from. It really shouldn't be much more than a couple degrees warmer in there than it is in the rest of the room. I'm guessing your cabinet doesn't have an intake.

 

[haupiapie]

Do you have a passive intake vent? 435 / (2x2x5) = 21.75.

You are exchanging the air in your tent 21.75 times per minute, providing that your extractor fan has a passive intake to pull from. It really shouldn't be much more than a couple degrees warmer in there than it is in the rest of the room. I'm guessing your cabinet doesn't have an intake.

Yes no intake. Just negative pressure with the inline fan. So using the 8 inch wouldn't matter?

 

[TreehouseJ]

You need an intake. Should be something like 120% the diameter of your exhaust, so a 6" fan should have an 8" hole to pull from, otherwise you might not be doing a whole lot in terms of cooling, and your extraction fan will eventually fail. I'm not 100% on intake size, but I would make it at least the same size as your extractor fan.

You could probably get by with a small PC fan, and for sure with a 4" inline pulling ~150 cfm, providing you've got a 4"-6" passive intake.

Your LED's shouldn't need very much cooling at all.

 

[haupiapie]

You need an intake. Should be something like 120% the diameter of your exhaust, so a 6" fan should have an 8" hole to pull from, otherwise you might not be doing a whole lot in terms of cooling, and your extraction fan will eventually fail. I'm not 100% on intake size, but I would make it at least the same size as your extractor fan.

You could probably get by with a small PC fan, and for sure with a 4" inline pulling ~150 cfm, providing you've got a 4"-6" passive intake.

Your LED's shouldn't need very much cooling at all.

Thanks, actually I take that back, this cab was given to me by a friend and there is passive intake holes, but they are pretty small so it appears to not be enough. Since I don't feel like modding the metal cabinet, I may duct a small fan like you mentioned blowing into the passive intake holes. Hopefully that will work.

 

[TreehouseJ]

If you are still struggling with heat, try freezing milk jugs filled with water. I've cooled 2x cooltubed 600w hps in a sealed closet using 2-3 gallons per night.

 

[Vanilla Phoenix]

Yeah, you're supposed to have a larger intake than your exhaust for sure. You can get a larger fan and it won't really do shit. And Tree is right, with that much stress on your fan, it's gonna burn it up. If you had good intake size, that fan could suck a golf ball thru a garden hose in the space you're in!! I bet your temp would practically be the same as the room it is pulling air from.

If you don't wanna make larger intakes, maybe use fans blowing in. Still would be better to make intakes larger.

How big is your intake now?

 

[chronosync]

Jugs on the floor, TreehouseJ? Good thing this thread reminded me of something I did today and might actually cook my plants at lights on now that i think of it I'm having the opposite problem. They are ready for flush, No Way I'm fuckin it up now! Thanks haupiapie !

 

[TreehouseJ]

Jugs on the floor, TreehouseJ? Good thing this thread reminded me of something I did today and might actually cook my plants at lights on now that i think of it I'm having the opposite problem. They are ready for flush, No Way I'm fuckin it up now! Thanks haupiapie !

I would put them in a shallow plastic container on the floor. I also keep my buckets in ice water tied down in "gorilla tubs". I add ~.5 gallon per bucket per day. I'm sure this also helped to cool the room. (Without the ties, my buckets would float out and tip over)

 

[haupiapie]

Yeah, you're supposed to have a larger intake than your exhaust for sure. You can get a larger fan and it won't really do shit. And Tree is right, with that much stress on your fan, it's gonna burn it up. If you had good intake size, that fan could suck a golf ball thru a garden hose in the space you're in!! I bet your temp would practically be the same as the room it is pulling air from.

If you don't wanna make larger intakes, maybe use fans blowing in. Still would be better to make intakes larger.

How big is your intake now?

There are four holes with a 2 inch diameter (8 inches total), which should be enough, however ,on the outside of the cab, the holes are covered by a screened frame that has material similar to a carbon filter cover which acts as a dust filter. The inside of the cab has a light baffle to prevent light leak that the filter/cover couldn't block out.

Rather than using a fan to blow in air, I'm thinking of creating more 2 inch diameter holes next to the other holes. Perhaps 2 more holes to make it 12 inches total. Also, I'm wondering if the passive intake can be too big ? Also keep in mind that I will still be using the dust filter to cover the holes from the outside, and there is carbon filter for the inline fan. So maybe making it 12 inches total diameter for the passive intake will help?

Thinking about using this to cut the holes:
https://www.amazon.com/Malco-HC1-2-Inch-12-Inch-Accessory/dp/B000289542

I'm hoping that will do it.

 

[Vanilla Phoenix]

I believe I read somewhere on here that you generally want twice the intake as outtake using a passive intake system. I'm not sure what the equation is but keep in mind if you have a 4" exhaust and you have four 2" intakes, that's not big enough.

Something about the cubic inches don't match up. Like if a 4" round hole has 100 cubic inches, a 2" hole only has 30 cubic inches. If you do a search on here you can probably find the equation to figure out how many cubic inches you need. Because cubic inches is really what you need to be looking at, not diameter of hole. Whenever I used to make boxes with passive intakes, I always just made two holes the same size as my intake to be safe.

Hope that helps.

 

[TreehouseJ]

There are four holes with a 2 inch diameter (8 inches total), which should be enough

If I'm doing the math correctly.. and each of your 2"x2" holes are actually 3.16 sq inch holes..

What you are shooting for would be..

(6x6=36/4)x3.16= 28.44square inches of vent hole. x 120%= 34.128 square inches of vent hole. So you would want 11 2"x2" holes. So... I guess you weren't as far off as I was thinking.. I'm still on the john, waking up.

I think it's still a bit too early to explain the math. If any of that confuses you, imagine your fan was a square, and your holes were all squares, and then divide your areas by 4 and multiply by 3.16 to find the area of your circles.

Buy yourself a dremel if you are going to be modifying plastic or sheet metal. Hole saw kits are 'spensive but worth it.

Once again, I'm not 100% on the vent size. I would trust VP before myself, and do (6x6=36/4)x3.16= 28.44square inches of vent hole. x 200%=56.88/3.16= 18 2x2 holes.

 

[Vanilla Phoenix]

Don't trust me!! Lol! I just know two 2" holes aren't as big as one 4" hole!