Question about ventilation and fans

[MarieJN88]

This is my grow box, still under construction.. (Length: 90cm x Width: 60cm x Height: 75cm = 0.41 cubic meter)


My question is does this 30/35CFM fan enough for outake?



THX

 

[Zakola]

For a small box like that you don't really need an intake fan for fresh air the exhaust fan could work to suck the air in, a simple hole (at the bottom) would work + it can be stealth. For exhaust it depends to where and how far the exit is. So where the outake go?

 

[MarieJN88]

to a small window taking to the ventilation shaft.. and 35cfm is it enough?

 

[IndicaDom]

Well how many exchanges of air do you want per hour? Lets go with 20 exchanges of air per hour, your box is .41 cubic feet correct? That means we need a fan that can clear out .41 cubic feet x 20 exchanges per hour = 8.2 cubic feet per hour. Now your fan is rated at 30 - 35 CFM, what does CFM mean again, cubic feet per minute. Now we can see we only need 8.2 cubic feet per hour, and our fan does 30 cubic feet per minute. So we can see that we are well above our threshold for being able to exchange the air in a .41 cubic foot box 20 times per hour. So yes to answer your question that fan should be more than enough to exhaust that box with a proper passive intake.

 

[IndicaDom]

Now looking at the picture again it seems you aren't closing the box off at all, you are simply leaving the side open, in this case the fan on the ground is more than enough and the PC fan can be removed.

 

[MarieJN88]

Now looking at the picture again it seems you aren't closing the box off at all, you are simply leaving the side open, in this case the fan on the ground is more than enough and the PC fan can be removed.

I didn't close my box yet coz i still need to add more lights and fix my fans before..
So now I have 2 fans of this maybe i could use them to exhaust more air from my box one on each side to take the heat of the bulbs with 2 passives intake opposite to them on the bottom of the box.

 

[IndicaDom]

I didn't close my box yet coz i still need to add more lights and fix my fans before..
So now I have 2 fans of this maybe i could use them to exhaust more air from my box one on each side to take the heat of the bulbs with 2 passives intake opposite to them on the bottom of the box.

That sounds perfect. I think passive intake is the best and with the fans pulling air past the bulbs you shouldn't have a problem keep the cabinet cool.

 

[MarieJN88]

The temperature in my box is above 30 degree Celsius, i have 2 outake fans and 1 intake.. how can i resolve it?