the "trick" with chillers (as you just learned) is getting a nice COLD start. a lot has to do with the size (HP rating) of your compressor. most "smaller" compressors cant handle the heat load of "modern" CPU's, so you can use your res a buffer between the CPU and the compressor. depending on the size of your res, it might take 1 hour to "take away all the cold energy" the compressor put into it...does that make any sense?
that (and condensation) is why people insulate the heck out of everything on their chiller; trying to keep the CPU as the only heat source the compressor has to overcome. unfortunately, during the "chill down" period is when you can get condensation on the tubes/WB/res...
condensation only happens to things that are colder than the dew point of the air its in.
dew point chart , its dependent on air temp AND (relative) humidity.
this is also the time that you run the risk of freezing your coolant IE if your using JUST distilled water, and you get it -0C its going to freeze. so you start putting car antifreeze in the mix, unfortunately, that makes your "water" thicker and thus slows down the flow rate with lowers the efficiency of you WB. there are a few other additives that many chillers' use but im not a "pro" @ this...
GOOD LUCK and BE SAFE keep an eye out for condensation although it *MIGHT* not kill anything, the possibility of a dead mobo/CPU/vid card/PSU/MEM is always there!