HVAC Common Terms

HVAC Common Terms

Air Changer per Hour (ACH) – how many times the air is changed in the room per hour using ventilation systems.

BTU (British Thermal Unit) – a measurement of heat used in HVAC systems. The amount of energy needed to raise the temperature of one pound of pure water by one degree Fahrenheit.

Chiller – an appliance that removes heat from the liquid phase. This is done through vapor-compression or refrigeration cycles. The cooled fluid from this process passes through air condition systems reducing the air temperature. This device is the main component of HVAC systems.

Ductwork – special channels and pipes that are used in AC and HVAC systems for airflow.


Dehumidifier – an appliance that reduces the level of humidity in the air.

Heat Pump – a simple device designed to absorb heat from a colder space and release it to warmer places.

heat pump

Split Zone Air Conditioner – a type of air conditioning system. These systems have two separate units, an outdoor and an indoor unit. The condenser is located in the outdoor unit, and the evaporator is located in the indoor unit. Both units are connected with a lineset or pipe filled with the refrigerant.

Indoor Unit
indoor unit
Outdoor Unit
outdoor unit

Thermostat – a device that controls and regulates the systems. This device allows you to easily set the optimal temperature inside your home.


Refrigerant – is a fluid that is used in the refrigeration cycle in some popular devices like air condition systems or heat pumps. These substances mainly transfer the heat by changing phases from liquid to gas in HVAC devices. Examples of popular refrigerants are R410a, R134a, R-717, and R-290.