There is definitely something wrong with the heat exchangers. I built 2 basic heat exchangers with a basic heat vent on one side and a basic coolant cell on the other side of each one. I placed some cells away from them to build up some heat in the reactor and waited untill they ran out. I would expect since there are 2 vents that get rid of heat at 4 each that the total heat should eb going down by 8 each tic. Instead in the heat window, the tic goes up and down a bunch, sometimes the total heat even goes up at this point with no active cells. It seems like the heat is just getting moved around or double counted somehow.
If you press escape, you can mute audio in the settings menu