HVAC Refrigeration Cycle + Basic Vocab Terms

Blue

Common

Red

Power

Green

Blower Motor

White

Electric Heat

Yellow

Contractor

Orange

Reversing Valve

1st Step of the Refrigeration Cycle

Compressor

2nd Step of the Refrigeration Cycle

Condenser

3rd Step of the Refrigeration Cycle

Metering Device

4th Step of the Refrigeration Cycle

Evaporator

Compressor

Vapor Pump & only pumps refrigerant in vapor form

Condenser

Rejects heat

Metering Device

Regulates the flow of refrigerant

Evaporator

Absorbs the heat

Latent Heat

substance with no change in temperature

Superheat

Heat added to vapor above its boiling point.

Subcool

Heat removed from a liquid below its condensation point at a given pressure.

Sensible Heat

Heat that causes a change in temperature that can be measured with a thermometer.

Dew Point

The temperature at which air becomes 100% saturated and moisture begins to condense.

CFM

The volume rate of airflow moving through a space or duct per minute.

Delta T

The temperature difference between two points in an HVAC system (usually supply vs. return air).

Bubble Point

The temperature at which a liquid refrigerant blend begins to boil.

Saturation Temperature

The exact temperature at which a refrigerant changes phase (boils or condenses) at a given pressure.

Static Pressure

The outward pressure exerted by airflow perpendicular to duct walls, measuring resistance to movement.

Refrigeration Cycle

The continuous process of circulating refrigerant to absorb, move, and reject heat using compression and expansion.

Heat Pump

A reversible refrigeration system that provides both cooling and heating by reversing refrigerant flow.

Liquid Line

The high-pressure pipe carrying subcooled liquid refrigerant from the condenser to the metering device.

Airflow

The movement and circulation of air through an HVAC system and duct network.

Flash Gas

The instant vaporization of a portion of liquid refrigerant when passing through a pressure drop or metering device.

Suction Line

The low-pressure pipe carrying superheated vapor refrigerant from the evaporator to the compressor.

Gauge

Instruments used in HVAC to measure high-side, low-side, and system pressures for diagnosing and servicing refrigeration loops.