cooling your grow room

[videoman]

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.

(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

[danke]

Can't I just look at a thermometer?

To much math for me.

[juniorman8]

I think I'll save that formula for later use. Thanks videoman!

[sombodysomewhere]

What about the size of the room that has to affect the temps.

[juniorman8]

you have to take all factors into consideration. For instance, videomans formula puts me at +7 degrees (400W light & 180cfm exhaust). I stay real close to +4 though. My box is 4x2x6 with passive intake air from my office. It's been a while back but I remember someone posting another formula for figuring how strong your exhaust fan needed to be for the size of your box. How fast you can exchange the hot air inside has a lot to do with it also. Just my opinion.

[videoman]

So the formula is very close to correct for you. One bearing is that you obviously did your intake properly. The size of the room, meaning a much larger room, simply takes longer to have the temps raised, however it is the watts that produce the heat, not the size of the room. This is meant simply as a guide to give an idea of how much cfm you need. I guess it is assumed that most grow rooms are not the size of warehouses.

I think in your case, a difference of only 3 degrees between your grow room and the formula, proves it to work. Of course, if you had neglected, or did a poor job of designing the intake, the temps would simply rise.
Peace

you have to take all factors into consideration. For instance, videomans formula puts me at +7 degrees (400W light & 180cfm exhaust). I stay real close to +4 though. My box is 4x2x6 with passive intake air from my office. It's been a while back but I remember someone posting another formula for figuring how strong your exhaust fan needed to be for the size of your box. How fast you can exchange the hot air inside has a lot to do with it also. Just my opinion.