| A | B |
|---|
| Absolute pressure | Positive pressure measurements that start at zero (no pressure at all). Also gauge pressure plus the pressure of the atmosphere (14.7 psi at sea level at 70°F). |
| Atmospheric pressure | The pressure exerted on all things on the earth’s surface as a result of the weight of the atmosphere. It is 14.7 psi at sea level at 70°F. |
| British thermal unit (Btu) | The amount of heat needed to raise the temperature of one pound of water one degree Fahrenheit. |
| Cold | A relative term for temperature. Cold means having less heat energy than another object against which it is being compared. |
| Conduction | A means of heat transfer in which heat is moved from one material to another by means of direct contact. |
| Conductor | A material in which the transfer of heat by conduction occurs easily. |
| Convection | The transfer of heat by the flow of liquid or gas caused by a temperature differential. |
| Enthalpy | The total heat content (sensible and latent) of a refrigerant or other substance. |
| Floodback | Refrigerant returning to the compressor in the liquid state. |
| Gauge pressure | The pressure measured on a gauge, expressed as pounds per square inch gauge (psig) or inches of mercury vacuum (in Hg vac.). Also pressure measurements that are made in comparison to atmospheric pressure. |
