So...about my Vessi and temperature, the folks from the labs actually emailed me directly. I think my Vessi may have an issue. It took 4 days to get to 41 degrees but from what I've seen here, thats not normal. Bob had talked about an algorithm about how the unit cycles and all that. Here is from an engineer:
From the performance tests we have done, the displayed temperature may continue to be 41. However, that reading is just from one spot towards the bottom of the vessel. The beer above that point is actually colder than that spot. From the tests we have done, it all depends on the ambient temperature of the room the Vessi is in, the set point for temperature, the specific gravity of the beer, the alcohol content of the beer, and the amount of liquid in the vessel. Our goal is to be +/- 2F at any place in the vessel to your set temperature.
It is normal for the unit to take more than 24 hours to get from 70 to 39. Our algorithms for temperature control purposefully slow the cooling down to prevent over-chilling (and freezing) the upper section of the vessel while going from max temp to set temp. For set temperatures at 46F and above, the unit will cool until it reaches the set temperature straight away with no delays, because we did not see over-chilling issues at that temperature set point.