I do remember reading a build thread on another forum where the aluminum tubing itself dispated enough heat that fans weren't warented. However, I believe he was running less diodes. It would be interesting to know what the temps would be with and without the fans.

interesting build tagging along

Yes more than likely if the fans fail things will get pretty warm, however depending on the design on many fixtures and how they are enclosed this could be common issue with LEDs. I also ran some LEDs on my previous nano on just plain old flat bar without fans, they did run very hot but still appear to work as new a year later so worst case scenario doesn't really mean frying everything.

Some testing will give better answers but the design may still work if only one fan fails and if it does appear to be a serious threat I do have some plan B's to integrate as safety devices, temperature monitoring is certainly one of them. The other thing is the drivers will be mounted on the same heat sink and they will shut down if their temp rises above 150C.

The fans should however be pretty reliable seeing that they are the same used in some flat panel TVs which would also be pretty reliant on them. Plus I do have two back up fans on hand for a quick change if needed.

With the tube style heat sink if the fans stopped the air in the tube would just keep getting warmer with no air circa. Regular heat sinks with open fins will dissipate a little of the heat.

I think you have a good thing going here sphelps, fairly inexpensive heatsink & I really like your design, well planned.

Well it depends, typically the DIY style is to get a huge chunk of heat sink and simply hang that over the tank so yes it would dissipate a lot more heat than tubes. However some purchasable fixtures use very little heat sink to keep weight and cost down and they do rely heavily on forced air movement (Just like the cpu in a typical computer). On top of this everything is enclosed in a nice tight shell to make things look nice which will add to problems if fans stop working.

So certainly more reliable on fans than what is typically seen in the DIY apps but I think in general all LED fixtures seem pretty reliant on their fans. I guess some of the purchased fixtures may very likely have protective shut off for high temps which I may or may not need to add.

Thanks Grizz, but keep in mind isn't necessarily that inexpensive. The aluminium tube itself cost me $90 and it took two hours just to cut it all up. Then there's the cost of welding as well. For me personally my cost stopped at $90 but others without the tools would be looking pretty close to $300 min. In comparison I could have gotten a standard finned heat sink large enough for around $100-$150, less if I went will multiple smaller ones.

I just ordered the u-channel that I plan to use for my build. I was going to go for the large heatsinks but couldn't source them cheaply enough in Canada. Six 6' x 2" u-channels plus one 6' x 4" u-channel all precut for me by a local machine shop for $102. Will probably start it when I get back from MACNA on Tuesday. Really interesting build using this here: http://www.reefcentral.com/forums/sh....php?t=2026851

Here's the heat sink all welded up and drilled.

http://i11.photobucket.com/albums/a1...1/DSC_6766.jpg

http://i11.photobucket.com/albums/a1...1/DSC_6768.jpg

And here's the beginning on the LEDs being mount, all blues are mounted.

http://i11.photobucket.com/albums/a1...1/DSC_6771.jpg

http://i11.photobucket.com/albums/a1...1/DSC_6770.jpg

Should be seeing some light this week :mrgreen:

Just a quick question...are you using any kind of nylon or other non-conductive material between the stars and the screws. I have been researching DIY fixtures for over a year and read hundreds of builds...almost all of the ones where screws went directly to the star resulted in shorts and a lot of re-work. You may have them there and I just don't see them.

Even these would work: http://www.ncix.com/products/?sku=61...tech.com%20Ltd

Yeah there are very small washers and I've tested each one for shorts.

Although I just went and retested and I did find one short so now I'm a little concerned. I think I'm going to go get some wider washers to be on the safe side. Thanks for the heads up!