Variable refrigerant flow (VRF) systems vary the flow of refrigerant to indoor units supported demand. This ability to manage the quantity of refrigerant that is provided to fan coil units placed throughout a building makes the VRF technology ideal for applications with varying loads or where zoning is required. VRF systems are available either as heat pump systems or as heat recovery systems for those applications where simultaneous heating and cooling

is required.

In providing superior comfort, VRF systems offer design flexibility, energy savings, and cost effective installation. This descriptions can define the advantages of a typical VRF system; describe the advantages offered by the most advanced outdoor units available, and provide general guidelines for selecting a heat pump system versus a heat recovery system. Variable refrigerant flow systems are electric systems that use air or water source heat pumps to provide space heating or cooling to a building's open spaces. VRF systems will condition multiple zones in a very building, every of which can have completely different heating and cooling wants. Using refined management technologies, VRF systems have the flexibility to modulate the quantity of refrigerant sent to every zone severally and in tune with various and dynamical house learning loads, thereby increasing energy savings. VRF systems use refrigerant to manoeuvre heat throughout a building that permits them to use energy a lot of expeditiously.

VRF technology has been obtainable in world markets for a few times. Until recently, there has been little interest in VRF technology in North America. Lowering the environmental problems and market adoption of the key components of VRF systems such as variable speed fans and compressors etc. have helped increase the attention of VRF systems in the market.

VRF systems are essentially large-scale versions of the ductless mini-split air conditioning systems that have made inroads into several niche residential and commercial markets in the Upper Midwest. VRF systems move heat between an outdoor unit and one of many indoor units used to heat or cools an individual zone in a building. Sophisticated controls enable multiple indoor units to be placed on constant main refrigerant loop so the amount of lines required to manoeuvre refrigerant throughout the building will be decreased. Variable speed compressors and fans work to minimize energy use once the system is working below part-load conditions.

Key components

Outdoor unit

The main heating and cooling plant of a VRF system is sometimes an air supply or water supply apparatus. Ground supply or "geothermal" apparatus systems have tried effective in some western applications. The purpose of the outside unit is to exchange heat with the outside atmosphere, either by discharge heat (when cooling) or fascinating heat (while heating). Heat is changed with the outside atmosphere employing a device crammed with R-410a refrigerant, which is then pumped throughout the building to one of many indoor units. Variable speed mechanical devices are used so lower compressor speeds will be used throughout part-load circumstances.

Indoor units

Refrigerant from an out of doors unit is tense to 1 of the many indoor evaporator units, every of that is chargeable for heating and cooling a private zone in a very building. Indoor evaporator unit’s management the quantity of warmth being drop to an area victimization linear or electronic growth valves (EEVs). Indoor evaporator units exchange heat between the refrigerant and close air by processing air over the unit's evaporator coil. During the warmth exchange, the refrigerant either condenses or evaporates. Refrigerant returns to AN negotiator heat recovery unit or on to the outside unit, where it is subsequently heated or cooled again.


VRFs use a R-410a refrigerant that is a lot of energy dense than water or air. This means that a smaller volume of vapor or liquid refrigerant is required to move the same amount of heat. This can lead to pumping motor savings and a lot of economical transfer of warmth to/from zones. R-410a is a non-ozone depleting compound; however, R-410a does have a high global warming potential, so it must be collected and disposed of properly.

Heat recovery unit

A heat recovery unit (HRU) permits for the coincident heating and cooling of many individual zones that ar co-located on constant main refrigerant loop. For example, AN HRU would possibly extract heat from the refrigerant arriving from a cooled zone to heat refrigerant feat for a special zone that's presently in heating mode. By reusing the heat that can be extracted locally, HRUs can reduce the size of the overall heating and cooling loads that must be satisfied by the outdoor unit.

Efficient motors

Fan coil units can be outfitted with electrically efficient variable speed motors, such as electronically commutated motors (ECMs), to modulate airflow rates with changing heating and cooling loads. Fans that operate at lower speeds when heating and cooling loads are low use far less energy and often have the added benefit of being quieter.