The practice of dividing a home into small sections for heating and cooling control. Each section is selected so that one thermostat can be used to determine its requirements.

Device used to measure pressure in inches of water.

Temperature read with a thermometer whose bulb is encased in a wetted wick.

Volatile Organic Content

The gaseous state of a substance.

A pump used to remove air and moisture from a refrigeration system at a pressure below atmospheric pressure. This procedure is done prior to charging the system and assures that the system is free from all non-condensibles.

A unit of measure for cooling capacity. One ton = 12,000 BTUs per hour.

Is the practice of selecting an air conditioner with a cooling capacity smaller than the cooling load.

An automatic valve that feeds refrigerant  to the evaporator coil. The amount of refrigerant fed to the coil is based on the line temperature leaving the coil. This is the preferred method to feed refrigerant to the coil as it is more accurate than an orifice or flo-rator commonly used. This is commonly call the TXV.

A temperature sensitive switch for controlling the operation of cooling and heating.