Glossary of Terms

AHU
Air handling unit. An air handler is usually a large metal box containing a blower, heating or cooling elements, filter racks or chambers, sound attenuators, and dampers. Air handlers usually connect to a ductwork ventilation system that distributes the conditioned air through the building and returns it to the AHU.
Air Conditioning
Air conditioning – a system for controlling the humidity, ventilation, and temperature in a building or vehicle, typically to maintain a cool atmosphere in warm conditions
Air Source Heat Pumps
An air source heat pump (ASHP) is a system which transfers heat from outside to inside a building, or vice versa. Under the principles of vapor compression refrigeration, an ASHP uses a refrigerant system involving a compressor and a condenser to absorb heat at one place and release it at another.
BTU
The British thermal unit (BTU or Btu) is a traditional unit of energy equal to about 1055 joules. It is the amount of energy needed to cool or heat one pound of water by one degree Fahrenheit. In science, the joule, the SI unit of energy, has largely replaced the BTU.
Cassette
An indoor unit that is fitted in to a false ceiling. Return air is drawn up through the central core and then discharged through the four edge slots. A popular form of office or retail air conditioning.
Compressor
An air compressor is a device that converts power (usually from an electric motor, a diesel engine or a gasoline engine) into kinetic energy by compressing and pressurizing air, which, on command, can be released in quick bursts. There are numerous methods of air compression, divided into either positive-displacement or negative-displacement types.
Condensate
Water condensation is formed with an indoor unit as a natural by product of the cooling process. This water is collected in a tray and is piped away to drain. Often it is not possible to provide a gravity drain and so a special pump is fitted to remove the water to a suitable waste point.
Condenser
A condenser unit used in central air conditioning systems typically has a heat exchanger section to cool down and condense incoming refrigerant vapor into liquid, a compressor to raise the pressure of the refrigerant and move it along, and a fan for blowing outside air through the heat exchanger section to cool the refrigerant inside.
Controller
A hard wired or hand held controller for operating Air con equipment.
Ducted unit
Built in Air conditioning unit that distributes from a grille in the ceiling or wall.
Ductwork
Preformed galvanised steel sections which air is travelled through by means of fans to a distribution grille in the wall or ceiling.
Fan Coil unit
A fan coil unit (FCU) is a simple device consisting of a heating or cooling coil and fan. It is part of an HVAC system found in residential, commercial, and industrial buildings. Typically a fan coil unit is not connected to ductwork, and is used to control the temperature in the space where it is installed, or serve multiple spaces. It is controlled either by a manual on/off switch or by thermostat.
Ground Source Heat Pump
A geothermal heat pump or ground source heat pump is a central heating and/or cooling system that pumps heat to or from the ground. It uses the earth as a heat source in the winter and as a source of cooling in the summer.
Heat Exchanger
An item of equipment that transfers heat from one fluid to another without allowing them to mix.
Heat Pump
An Air conditioning system that can provide heating aswell as cooling by reversing the flow of refrigerant. Most air conditioning equipment are now Heat pumps.
HR
Heat Recovery ventilation. Heat recovery ventilation, also known as HRV, mechanical ventilation heat recovery, or MVHR, is an energy recovery ventilation system using equipment known as a heat recovery ventilator, heat exchanger, air exchanger, or air-to-air heat exchanger which employs a counter-flowheat exchanger between the inbound and outbound air flow. HRV provides fresh air and improved climate control, while also saving energy by reducing heating (and cooling) requirements.
Mechanical Services
Mechanical services – Heating, plumbing, ventilation and Air conditioning services.
Multi Split System
Split type air con system which has two indoor units and one outdoor unit.
Refrigerant
Fluid that flows through sealed Air con pipe work in a cycle from indoor to outdoor unit changing from liquid to gas and back again. The properties of refrigerant means that it will evaporate and absorb heat and then condense back to fluid and release the heat.
Split System
Split type Air conditioning system is a one indoor and one outdoor unit in the system.
Ventilation
The provision of fresh air to a room or building etc.
VRF
Variable refrigerant flow is an HVAC technology. VRF uses refrigerant as the cooling and heating medium, and allows one outdoor condensing unit to be connected to multiple indoor fan-coil units, each individually controllable by its user.