Dresser Grow - Ventilation Help

[Didiastole]

Hello there.

I need some help with my dresser grow box. My dresser is 27 x 30 x 13 (Width x Height x Depth).
I have 4 x 12mm, 1 x 10 mm, 3 x 8mm PC Fans. I don't know their power or CFM. The bigger the more air it blows.
I am planning on build a 250w CFL grow, 10 or 8 cfl light bulbs. No ducting because I couldnt figure out how to manage it yet.

I have read that it is not necessary to have intake fans, just exhaust and let the fluid dynamics do its job, but here where I live the temps hits 80+ degrees very often.

This is what I sketch'd for this dresser grow (please don't mind the metric measures):

Two 12mm fans intake at right and two 12mm fans exhaust at left to make sure all air from outside blown to the bulbs are pulled out after travelling a - almost - straight path.
And 3 or 4 intake fans on bottom part blowing fresh air directly on the plants or above them(I am not sure if this is the best option) to provide CO2 and cool the temp.

I need any suggestion, tips or even critics on this sketch. Do you think the top fan scheme will do its job on keeping the temps down? Do you think I should only provide exhaust?
Thank you!

 

[415friendly]

That many CFL bulbs in that small a space will raise your temperatures too high.

I ran 8x45w CFLs (each were 150w equivalents) in a 23 x 36 x 48 cabinet and even with extraction fans, had temperatures climb up into the 90's.

I upgraded to a Mars Reflector 96 and saw my temperatures drop and my light intensity increase.

I would consider investing in a cheaper LED for under $100 ( the Mars 300 springs to mind) if you're on a budget.

 

[Didiastole]

You are right. I've considered upgrading to LED. The only concern now is to find the right led panel in my region. I will learn more about leds now. Any suggestion on that?

 

[Locoschmoko]

You are right. I've considered upgrading to LED. The only concern now is to find the right led panel in my region. I will learn more about leds now. Any suggestion on that?

Hello friend . as the previous guy stated Marshydro are a safe bet, you can pick them up on Amazon or there own website. I am currently using the reflector 48 as I've got a small grow space and it's working wonders. LED'S and the Mars Hydro Reflector 48 in my experience run SO cool you will probably get away with 1 pc fan exhaust and a passive intake, reducing electric consumption and noise levels. The amount you will spend on CFL'S and venting the heat from them you will be far better investing in an LED panel such as a Marshydro 48/96 reflector or the Mars 300. From what I've heard though the Mars 300 isn't an official model from them though? Any questions on Marshydro products you should head over to the Marshydro grow light discussion thread here

Loco

 

[Dwight Monk]

Problem with LED is distance, can't have them right on top of plants like CFL and need some space on top of the light for air flow (as most have fans on the top), so with a 30" starting height minus distance for light minus pot height doesn't give you a lot to work with for plant height, not saying it can't be done but when I bought my 3' grow box I realized it was going to be tough growing thru full cycle in it and built myself a taller one (which turned into two taller ones on top of prebuilt one I bought). I have 4 total small computer fans in my boxes I built, and seems to get plenty of air flow far as I can tell so I wouldn't think you would need much more than 4 for the cubic feet or area you working with, in my mind better to have the inlet fans lower and the upper fans as exhaust only as heat rises and all that good stuff (same as cooler air in a room is closest to the floor, hotter air closer to ceiling).

 

[Didiastole]

Thank you for your replies. I've been doing some research and yes, in my case LED would be good to solve heating, but height is a problem here. I dont have enough room to make sure it doesnt burn my plants. I better stick to CFL for a while...

I am thinking of placing all four pc fans right next to each other on the back of the dresser pulling air out, while having some intake fans on bottom along with some passive (holes).

 

[CookieMan]

Why not go taller. 30" will be very hard regardless.

 

[Lost In Nugs]

i would put 4 more fans under the canopy, this is where the rot starts when scrogging

i guess the one intake fan on the top would be counterproduktive,the extraction fan could suck way too much right through and the air from below extracted too slow

the heat rises on its own so there is no need to push it with an intake fan on the highest point. would NOT do it this way.

a lot of movement down below and a strong extake on the top to keep that negative pressure

 

[Lost In Nugs]

Another thing is that i would not go CFL or buy Diodes. I would learn more about DIY with white COB. They are dimmable easily and will not heat up your tent this much. I would say from 100W CFL and Mars Diodes about 50 to 70 percent is heat. Waste of energy imho. A good quality cob at the same wattage of your CFL will not be as hot as the CFL because its more efficient. Remember that. 300W of COBs will be cooler then your CFL and are wayyy further away. So the plants dont get as hot too.

My light costs 440 bucks of parts and is dimmable from 50 to 410 Watts for 85x55x120 cm. Use it at 220W in the picture and full blast on the smaller one.

I would go for 2x Bigger Cobs like Vero 29 at max 80W each or 4 smaller like the very cheap CLU048 1212 at 40W each. Go for 4000K for Veg and Bloom. You can dim the light from 0 to about 160W almost seamless. 4xClu incl top quality driver, cpu coolers, aluminum and everything you need for about 200 Dollars.

Look out for the thread 'My very first DIY COB fixture' in the DIY section of the Grow Forums. I am willed to help you build your own. Have a nice day