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How to cool your grow room


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#1 HeadPawthead

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Posted 02 August 2007 - 11:43 AM

A 90 CFM with a 600 watt light will raise your temperature above the intake by 21°. The 240 CFM fan will raise it 8°. 90 CFM wouldn’t be enough. It’s not the size of the cabinet that you want to take into consideration; it’s the wattage being used. Watts produce heat.

(600 × 3.2) ÷ 90 = 21.33

(600 × 3.2) ÷ 240 = 8

To find how much the light will warm the room with a different size fan you can just use the formula. Just take the wattage of the light and multiply by 3.2. Then divide the CFM of the fan to find how much the room will warm in Fahrenheit degrees.

For instance:

If the temperature of the intake air is 75° and you’re using a 600 watt light, the temperature would go up 5° if you used a 384 CFM fan. So, the temperature would end up 80°.

(600 × 3.2) ÷ 384 = 5

5° + 75° = 80°

Peace


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#2 hearmenow

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Posted 02 August 2007 - 12:04 PM

Great info VM. I will be putting this equation to the test once I get my exhaust fan, which is on the way. 400 X 3.2 = 1280/152 = 8 My home is usually around 74, so I can expect temps around 82 (F) in my growbox. Currently I'm running around 90, so this will really help.
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#3 HeadPawthead

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Posted 02 August 2007 - 12:09 PM

I've used this and it works fine, just don't forget along with exhaust, you need intakes. This could be anything, from a few simple holes drilled down low to adding a small pc fan to that hole, depending on your situation. General rule of thumb is, if you have a 3" exhaust, you'll need atleast 1.5 times that amount on your inlet. Peace

#4 Guest_pjboy31_*

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Posted 02 August 2007 - 12:58 PM

hey vid when you use comp fans do you just hardwirte them or add a plug?

#5 HeadPawthead

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Posted 02 August 2007 - 01:04 PM

Most pc fans are 12 volt, you can do a few things..... you can either splice an old charger to it, I actaully use an older 7 volt phone charger, sure its not 12 volts, but it is what I had handy and it does work. Another solution, although temporary, is you can use a 12 volt battery. If neither of these are to your liking, you can buy 110volt pc fans at radio shack. Peace

#6 green_nobody

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Posted 02 August 2007 - 05:40 PM

Most pc fans are 12 volt, you can do a few things.....
you can either splice an old charger to it, I actaully use an older 7 volt phone charger, sure its not 12 volts, but it is what I had handy and it does work.
Another solution, although temporary, is you can use a 12 volt battery.

If neither of these are to your liking, you can buy 110volt pc fans at radio shack.
Peace


if you got a old pc use the power supply of this one, they normally somewhere around 200-350W, so enough to power several fans of this class;)
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#7 Guest_pjboy31_*

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Posted 02 August 2007 - 06:00 PM

cool thnx guys .......................I want to cut some into my clone/seedling cabinet in the side so I can circulate air in there,. i will post pics later to show you all...........




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