Thanks Drew.......you've highlighted some pretty important stuff there that has been taxing my thoughts.
I made the chill box as a prototype really more for proof of concept, if I can iron out the bugs I'll make a more substantial one. when I'm ready to do longer test runs I'll simply be duct taping all the seams, that together with the simple idea I had for an expansion chamber should prevent it sucking in atmospheric air because of pressure changes even if some of the seals aren't 100%. I had the lid slightly a jar when I turned it on the first time as I had cables running under it so obviously not air tight.
I've also been thinking that if I start the air con unit a short while before the fans the evap will frost up and draw all the moisture out of the enclosure so it will be dry when I start the fans.
I think starting them both at the same time is just throwing the air around as the moisture is condensing out and that's why the fans frosted....some testing to be done there.
That's an excellent idea about putting a viewing panel in the lid.....I really do need a means to monitor whats going on.
The problem about the aircon unit cycling on and off is a little more vexing. It may have been better if I'd bought an "inverter" one as they moderate the compressor power rather than just on/off modes.
Of course you would not get this problem running a water filled reservoir as you do as you have quite a large heat capacity.
This is a more difficult one.
...the ideal solution would be being able to run the compressor continually to get the lowest possible temps without getting frost and having no need to cycle on off. You never know I may luck out there when I'm load testing, I may find it will run continuously with out frosting up, could even put a heat source in the box that kicks in below a certain temp to prevent it dropping too low and frosting everything when pc power use is low rather than have the compressor cycle on/off.
Or even better, I could sit the evap in a small reservoir of water that would come only part way up the evap rad, it would add heat capacity to the system and chill the evap during the compressor down times.
The problem behind this is frosting, if I can solve that then the compressor can run all it likes without need to cycle.
As regards hdd and ssd's your right , I was looking up mfr's spec last night, they don't like low temps.Edited by technogiant - 6/4/12 at 8:41am