Hi all, Question about compressing a gas. When you compress a gas it heats up. Does the compression supply a certain amount of energy to raise the temperature or does the compression merely raise the temperature using the energy that was already present in the gas? What I am getting at is the compression cycle in a heat pump. How much heat energy is supplied by the source and how much is supplied by the energy input? I was under the impression that the heat pump took all of the heat energy it needed from its source but needed electrical energy to compress the gas to initiate a phase change allowing it to release the heat.