Turn on heat simulator first. Then take an element (In my case it was water) and heat it or console set it to a certain (high) temperature with the save paused. When you unpause it cools down at a normal rate. Now set it back to where it was, while paused, and save it. When you unpause it now it will have magically lost several degrees. This is incredibly annoying when you have saves that are temperature dependant and you get everything just right then save it and it breaks!
EDIT: It does it whether the save is paused or not! D:<
Jacob, it is blatently a glitch, possibly caused by this save. It's not rounding, it's 100% confirmed losing more than 1/1.5 degrees of temperature, about four or five degrees. I don't know what the pressure accuracy is supposed to be but it is also causing problems. It seems to not do it when paused anymore, but it's still doing it when saving unpaused.
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Take this and save it to a new save. While unpaused, type in the console !set temp dstw 379.15 then immediately quicksave. Not only does it loose it's temperature instantly, it also shatters the tungsten (that may be normal though, it may be on the edge of breaking anyway).