Ballast heatsinks, for passive cooling?

[Outsiders71]

It's about that time again to start growing veggie seeds on my grow-shelf however I need to rework some things to make a better environment.

I have a 3 shelf setup, with 2x4' 2 bulb T-8 fixtures per shelf, all surrounded by 2mm mylar except for the back. Each fixture has a ballast that is meant to run 4 bulbs, so I'm over-driving 2 bulbs. This works great for light intensity but it also raises the heat substantially. To work around this last season I installed a window fan on the back of each shelf to pull out some of the heat. It worked OK.

I was wondering how I can more effectively remove some of the heat and if possible passively do so. I was thinking of re-wiring all the ballasts, and mount them on the outside of the fixtures. Then mount an aluminum bar such as one of these:
http://cgi.ebay.com/6061-T6-Aluminu...ryZ45024QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

On top of each ballast. Would these work effectively for removing the heat? Or would I be stuck in the same situation?

Lastly I have a 2 computer fans, one on each side, running on each shelf. I want to better supply air flow and was thinking of using 4" duct fans, and duct tubing. Anybody have experience with this?

Any ideas would be great!

 

[Not a Number]

Why waste your money on those aluminum bars which have minimal surface area for heat transfer when you can buy real heat sinks from just about any electronics store? Or find a junked stereo/audio visual receiver and gut it for the heat sinks on the power supply.

http://www.allelectronics.com/cgi-bin/item/HS-128/270/HEAVY-DUTY_ALUMINUM_HEATSINK,_TRAPEZOID_.html

 

[Av8tor1]

71,

I would recommend checking with your local community and tech college electronics teachers, I know at ours we have boxes of used high quality heat sinks left over from upgrades and stripping out donated equipment. We give them (and their fans) away to anyone who asks... big time savings

Not is correct, the key to dissipating heat is surface area and air flow... think fins, thin fins which facilitate airflow and maximize surface area

(old pentium 2 heat sinks are just about perfect for what you are looking for, and now considered obsolete for any puter type application)

Av

 

[Outsiders71]

So you think I should just order a bunch of CPU heatsinks and combine them?

 

[Outsiders71]

Best I could find:
http://www.sureneeds.com/fanp2secc.html

 

[Av8tor1]

If I was having issues with excessive ballast temps that that would be the unit I would try, they are rather long and narrow as opposed to being square like most current models.... but I would contact the local tech school first and try to find good used... BTW, you wont connect the blue wire, it is for "smart" cpu fan speed control or maybe RPM monitoring.. I forget which, but using the red and black only will make the unit run at full rpm...

the fans will be of the 12vdc flavor

 

[Outsiders71]

Think I might have found something better:

http://cgi.ebay.com/Fan-and-Heatsin...ZWD1VQQ_trksidZp1638.m118.l1247QQcmdZViewItem

 

[Av8tor1]

FWIW, looks good to me

be sure to use thermal tape or paste when mounting, can make a big diff...

 

[Outsiders71]

Yeah I'm going to get some thermal paste.

Do you know if it's possible to somehow power the DC fan's by wiring it somehow to the ballast? Would be sweet if possible...

 

[Av8tor1]

71,

No... not in any feasable manner, the best option is just use an old wall pack from an old printer or some other home/office/toy/appliance that used a 12vdc wall adapter.

I use one from an old canon 4100 printer, its about 13.5 vdc and has good current capacity.

If you cant find one, just ask around or go to radio shack or wally world, pretty common item

(you can use an old power supply from a puter if you want to complicate things a bit )

careful with the secondaries of your ballast, pretty high voltages mate... nice owie

Av

 

[Outsiders71]

Yeah I'm using a wall adapter now for the 8 fans I got going in there. Would like to consolidate if possible. Maybe I'll just get a cheapo PSU, and run the wires longer.