Let's talk fans....

The only part of your lamp that's gotta be in the grow chamber is the heatsink with wired leds attached. If you've got enough heatsink, (or wimpy-enough leds) you don't even need a fan. Remember, fans actually create more heat via motor operation, fan blade interaction with air molecules, etc. We just use fans to move heat where it does less damage. If you've checked out W.'s 10+2 lamp, he's got his sink cooling fan exhausting the heat out attached ductwork. Mine jes' fire in the general direction of my main exhaust, which is not so elegant.

There's a school of thought that tries to eliminate fans from led lamp design altogether. From a design perspective, it's a loftier aspiration. If your light's designed to operate without a fan, it can't overheat because of a fan failure. :thumbsup: Plus you save a couple watts on the fan motor, and a tiny bit of heat actually added by the fan's operation, etc.

I prefer to enter the battle planning to use enough concentrated watts to need a fan. This is war, baby! :gunfighter2: Plus, I like my electronics running cool.

But here's a thought: with the emitters spread out where the junction heat's not so concentrated -- if your heatsink is well-finned where it'll really catch some air -- you might be able to cool it with general circulation fans in the grow area, aimed so they just catch part of the heatsink. I played with this a bit while setting things up, and it seemed like it woulda worked. I'm kinda klutzy, though, and feel more confident with the fan stuck right to the sink.

A flaw in my design that's always griped me; I've got a fan running to cool the heatsink, but the "breeze" coming off the sink fan is firing 180deg away from the plants. :wtf:

Don't get me wrong, it works well. But I've been thinking of cutting a ~3" hole outta the center of a heatsink and mounting the fan so it cools the sink and fires the (slightly) warmed air downward at the plants. The cooling fan would then be functioning also as a circulation fan. It'd need a simple baffle to block the fan from simply pulling air straight through the hole. Just a thought--trying to redirect that wasted exhaust airflow into something beneficial.

Alternatively to the hub-and-spoke design, you could do a criss-cross design, or a square "catwalk" layout, too. Whatever layout you use, if your heatsinks are thermally connected, you don't need a fan behind every set of emitters. This is especially true with beefy, highly conductive heatsink stock.

I decided to think of my lights as "built-in;" after all, it's not like I'm running from room to room with the things--the flower room ain't goin' nowhere. So, rather than approaching the design from a traditional "portable" light paradigm, it became: "Okay, how do I light this specific space?" It's custom-made, baby! imp: