I’ll try not to get too technical on this subject, but there are some basic principles that you need to know before we get going. Firstly, we won’t be talking about hot and cold too often. It will be all heat, just at different temperatures above absolute zero (-460 deg F).
Next, we will be working in a unit of heat measurement known as a British Thermal Unit or Btu, and this is defined as the amount of heat required to raise or lower 1 pound of water 1 degree Fahrenheit.
Also it is important to remember that heat travels in one direction only; from a warm, high temperature area to a lower temperature area, and that we don’t “make cold”, we simply remove heat from one area and transfer it to somewhere else.