Well at the moment it is only a one off for Phil as for the future who knows??
The improvement with different gas will be lower temps also better heat disapation, it will do sub zero but that was not what I was after.
I was trying to build a unit on the edge of dew point at idle so say 16 degrees C and maybe 20 max under full load, the reason for this is so you wont need to insulate everything however I have found with this unit down to 3 degrees the tube does not get condensation build up on it at all only the copper block does, So if you insulate the blocks you should have no problems at low temps.....
I forgot to mention the fan will be 12V so it can be controled by the pc's fan controler