i just built my small grow cab but the temps are a little too high. After having the lights on for about 2 hours the temp was 88 and humidity at about 35%. I want to get the temperature into the 70's. My setup is a 95cfm pc fan attached to a carbon filter for exhaust, a 2'' hole for a passive intake, and a small pc fan blowing at the bulbs on the inside. Im using (2) 70w hps bulbs in a box with dimensions 28''X11''X35''. Any suggestions on how I can lower my temps? I considered adding another pc fan to the exhaust to make it stronger, share your thoughts. Thanx
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High Temps! HELP
- Thread starter The_Joker
- Start date
How round is your exhaust fan? a 2" hole seems reeeeediculously small even for a small fan.
First you'll need a room that's already in the low 70s.
You want 2 intakes equal in size to the exhaust. You're choking the cab at intake and possibly the filter too as axials are the least capable of dealing with resistance.
You want 2 intakes equal in size to the exhaust. You're choking the cab at intake and possibly the filter too as axials are the least capable of dealing with resistance.
grow1620
Member
hps throws off alot of heat....might look into cool tubing or separating them with glass from the grow area.
Is your carbon filter really thick? It may be too thick/dense for the fan to push though.
I wouldn't add a fan directly to the intake, if you hook up another fan, might as well be another exhaust, either another separate exhaust or stack 2 fans to increase static pressure to push through your filter better. Although having an external fan in the same room as the box, pointing at the intake would probably help also.
Shade your thermometer when doing temp readings too, it's more accurate.
...and definitely increase the size of your intake hole....if your exhaust fan is 4inchs by 4inches, your intake hole should be about 4 inches by 8 inches (twice as big).
also check out Scrubninja's link in his sig to his ultimate beginner's guide to PC fans there's a wealth of info in there.
sry I don't feel like converting metric atm, you said your fan is 120mm...so you need an intake that's 120mm x 240mm.
Is your carbon filter really thick? It may be too thick/dense for the fan to push though.
I wouldn't add a fan directly to the intake, if you hook up another fan, might as well be another exhaust, either another separate exhaust or stack 2 fans to increase static pressure to push through your filter better. Although having an external fan in the same room as the box, pointing at the intake would probably help also.
Shade your thermometer when doing temp readings too, it's more accurate.
...and definitely increase the size of your intake hole....if your exhaust fan is 4inchs by 4inches, your intake hole should be about 4 inches by 8 inches (twice as big).
also check out Scrubninja's link in his sig to his ultimate beginner's guide to PC fans there's a wealth of info in there.
sry I don't feel like converting metric atm, you said your fan is 120mm...so you need an intake that's 120mm x 240mm.
A 120 mm fan takes two 120 mm intakes. If you want to stick to 2 inch intakes, you'll want eight of them.
Rectangular/square intakes
Rectangular/square intakes
This is a really useful tool for comparing areas and such.
Don't bother reading any of the formulas - way too involved for stoners. Just plug your numbers in and "solve others". If you type in 12cm as the diameter for the 12cm hole of the fan, it tells us the area is 113.1 sq cm. So if we want two times, we need an area of 226.2 sq cm. If you start the crappy old calculator in Windows, type that number in and hit sqrt and that shows us for a square intake, we would need 15cm x 15cm.
Let's say your cab is a bit wider and so you need the intake to be 20 cm wide - and need to know the height to make it. Take 226.2 and divide it by 20. That's right, our intake needs to be 20cm x 11.31 cm.
If you think about it, it's not hard at all to find out how many smaller circular holes of any size you would need as well, using this page. In fact it should be obvious so I won't bother typing it
But I can let you know if you can't work it out.
All these numbers can be substituted for inches and used on the page I linked - just be sure to keep all measurements in the same units - such as cm. And be aware that 2x is the bare minimum you would want. If you are going to stick something like, say, aquarium foam over your intake hole/s, then kiss you calculations goodbye. Any that you block the intake is.....well....blocking the intake. So be aware.
Rectangular/square intakes
This is a really useful tool for comparing areas and such.
Don't bother reading any of the formulas - way too involved for stoners. Just plug your numbers in and "solve others". If you type in 12cm as the diameter for the 12cm hole of the fan, it tells us the area is 113.1 sq cm. So if we want two times, we need an area of 226.2 sq cm. If you start the crappy old calculator in Windows, type that number in and hit sqrt and that shows us for a square intake, we would need 15cm x 15cm.
Let's say your cab is a bit wider and so you need the intake to be 20 cm wide - and need to know the height to make it. Take 226.2 and divide it by 20. That's right, our intake needs to be 20cm x 11.31 cm.
If you think about it, it's not hard at all to find out how many smaller circular holes of any size you would need as well, using this page. In fact it should be obvious so I won't bother typing it
But I can let you know if you can't work it out.All these numbers can be substituted for inches and used on the page I linked - just be sure to keep all measurements in the same units - such as cm. And be aware that 2x is the bare minimum you would want. If you are going to stick something like, say, aquarium foam over your intake hole/s, then kiss you calculations goodbye. Any that you block the intake is.....well....blocking the intake. So be aware.
