Fan coil

Generic term used to describe the air moving section of any air conditioning unit usually containing the cooling/heating element. Can also be described in terms of a cassette unit, wall mounted unit, ducted type unit etc.

Cassette

A fan coil section originally designed for location within a suspended ceiling but can actually be installed into any type of ceiling that has a suitable ceiling void above. The body of the fan coil unit fits within the ceiling void with only a diffuser panel visible containing the air outlets.

Wall mount

A term used to describe a fan coil unit mounted at high level on a wall.

Ducted

A term used to describe a fan coil unit that is completely contained within a ceiling void. The treated air is supplied to the room via a ductwork run and ceiling mounted diffusers.

Ceiling suspended

A term used to describe a fan coil unit that is suspended from a solid ceiling or structure. Generally used where a suspended ceiling does not exist or is unavailable.

Floor mounted

A term used to describe a fan coil unit that is either mounted upon at low level upon a wall or fixed directly to the floor.

Condensing unit

The externally mounted unit that is the “engine” of the air conditioning system, providing cooling duty to the fan coil and rejecting the unwanted heat.

Multi-split

A term used to describe a system where there is a single outdoor unit (Condenser) connected to a number of internal fan coil units. The fan coils can each have independent control but are not able to simultaneously heat and cool.

Split system

The most popular type of single air conditioning unit. The internal fan coil unit is split (separated) from the external condensing unit and connected by means of small bore pipes and cables. Can have any type of fan coil fitted and be heat pump or cooling only.

VRF

Variable Refrigerant Flow – Uses a single external unit connected to any number of internal fan coil units. Similar to multi-split but differs by way the system is piped. VRF is at the pinnacle of packaged air conditioning design, providing solutions for almost any building layout or construction. VRF systems also have the most advanced control options and can be linked with most building management systems.

VRV

Variable Refrigerant Volume is a protected trademark of Daikin who originally developed this type of system. In all other respects it is as other manufacturers VRF system – as above.

VAV

variable air volume – A central plant system for large buildings, shopping centres etc.

close control

A term to describe a system that provides precision control of the internal temperature and humidity. For clean rooms, laboratories and specialist environments.

comfort cooling

A common term to describe cooling for comfort as opposed to close control.

condensate

Condensate water or the moisture removed from the air when the air is cooled. Condensate has to be removed and is usually drained by gravity or pumped.

COP

Coefficient of performance. A ratio used to determine how efficiently a heat pump operates. Usually expressed as a ratio such as 3 to 1. Where 3kw of heat will be produced for 1kW of input power.

Heat pump

The majority of air conditioning systems today are heat pump. In simple terms heat pump describes the systems ability to provide heating as well as cooling. However the heat produced is “recovered” from the external environment by reversing the refrigeration cycle i.e. the outdoor unit becomes the indoor unit and vice versa.

Inverter

An internal control that acts as a self regulating electronic “throttle” for the compressor, varying the available duty with the room load. Thus allowing more precise delivery of energy to match the required load at anytime.

Cooling capacity

Usually expressed in kW and refers to air a conditioning unit’s ability to remove or add heat to a space. The cooling capacity is further represented as a ratio known as SHR (sensible heat ratio). Example SHR 0.70 this is the ratio of sensible heat to latent heat capacity.

Latent heat

Latent heat is the amount of energy in the form of heat released or absorbed by a substance during a change of state (i.e. solid, liquid, or gas), or a phase transition. In terms of air conditioning latent heat is the energy contained within the moisture component of air.

Sensible heat

Sensible heat is that which affects the temperature of a substance and can be conducted, convected or radiated. In terms of air conditioning sensible heat is generated by the lights, computers, heat from the sun etc.

Total heat

The sum total of sensible and latent heat.