Handbook 752 Air Conditioning and Climate Control Sensible Heat As heat energy is added to a solid, its observed temperature will increase. This is called Sensible Heat . Latent Heat The process of changing the material’s state requires the addition of an extra amount of energy. This additional energy necessary to cause refrigerant to change state from a gas to a liquid or from a liquid back into a gas is called Latent Heat , which means unnoticed heat. It is called unnoticed because at the point at which a change of state is about to take place, a material will absorb a significant amount of heat without getting noticeably warmer.
For example, water boils at 212° F and applying additional heat will not raise the water temperature but will increase vaporization or evaporation rate resulting in steam vapor. NOTE BTU = British Thermal Unit 1 BTU = The amount it takes to raise one pound of water 1% F Technical Training 17