GLOSSARY
Sub-Cooling
Process whereas additional sensible heat (as opposed to latent heat) is removed
from condensed refrigerant liquid prior to the metering device. The proper
method for charging a system utilizing a TXV.
Temperature
Degree of hotness or coldness as measured by a thermometer; measurement of
speed of motion of molecules.
Test Light
Light provided with test leads, used to test or probe electrical circuits to
determine if they are alive.
Thermostat
A temperature control device. Typically mounted in conditioned space.
Thermostatic Expansion
Valve (TXV)
Thermostatic Expansion Valve. A metering valve which acts as a superheat
controller. Most are mechanically operated, and utilize a remote sensing bulb
attached to the outlet of the evaporator assembly (via a sealed capil-lary tube) to
regulate flow of sub-cooled liquid refrigerant at the evaporator inlet.
Therm
Quantity of heat equivalent to 100,000 Btu
Ton
A unit of measurement used for determining cooling capacity. One ton is the
equivalent of 12,000 BTUs per hour.
Vacuum
Reduction in pressure below atmospheric pressure.
Vacuum Control Systems
In some air conditioning systems, vacuum is used to operate dampers and
controls in system.
Vacuum Pump
Special high efficiency device (pump) used create deep vacuum within an AC/R
systems, for the purpose of moisture removal (dehydration), removal of non-
condensibles and can also be used, as well, for leak checking.
Valve, Service
Typically, a multi-ported valve used by service technicians to isolate remote
system components, as well as check pressures and charge refrigerating units.
Valve, Solenoid
Valve actuated by magnetic action by means of an electrically energized coil.
Volt
Electrical "pressure" applied to a circuit. One volt will cause one ampere of
current (volume) to flow in a circuit containing one ohm of resistance.
Water-Cooled Condenser
Condensing unit which is cooled through use of water.
Watt
Unit of electrical power. Volts x Amps = Watts.
Wax
Undesirable component in many refrigeration lubricants, which may separate
out of solution if cooled sufficiently.
Wet Valve
Device used in measurement of relative humidity. Evaporation of moisture
lowers temperature of wet bulb compared to dry bulb temperature in same area.
