What is Variable Refrigerant Flow?
Variable refrigerant flow (VRF) systems have been popular in Japan and Europe since the 1980’s but their benefits were largely unknown in North America until recently. Here’s a run down of what you need to know!
Types of VRF installation
- Cooling and heating only – provides either cooling or heating through simple system architecture, however only one action can be provided at a time; simultaneous heating and cooling is not possible.
- Heat recovery – facilitates the intelligent management of thermal energy in buildings. Heat is removed from spaces that require cooling and redistributed to spaces requiring heating. This use of VRF technology permits individual spaces within complex building potfolios to be separately zoned and controlled. The result is reduced energy usage and increased savings in utility costs.
- Increased heat redirection – facilitated by simultaneous heating and cooling between zones (‘total heat recovery’) within buildings;
- Increased energy savings – possible due to double heat recovery between zones using the refrigerant circuit and between refrigerant systems, using an ambient loop;
- Reduced size and weight – when compared with traditional rooftop systems or chillers of similar tonnage. The result is easier installation and reduced floor space requirements for dedicated mechanical rooms.
- Reduced capital costs – result because of space savings;
- Increases design flexibility – possible due to the variety of indoor units available;
- Phased roll-out – facilitated through the modular nature of VRF design. This enables phased conditioning of the building where different areas become occupied post-construction or renovation. It also ensures the system adapts to changes in room layouts.
- Increased co-efficient of performance (COP) – results in high system efficiency. For every 1kW of electrical power used by the system, generally 4- 5kW of heating/cooling is provided. COP can reach 8 – 10 in heat recovery mode.
- Increased flexibility in design – occurs because of longer pipe runs when compared to other refrigerant-based heat pumps.
- Increased input options – available with water and air source configurations to suit specific applications.
- Reduced noise pollution – when compared to conventional heat pump systems; possible because of the external location of VRF compressors. Compressors are located outside the zone being conditioned.
Components of a VRF system
Outdoor condensing unit
- Transfers energy to and from the outside environment
- Receives control information on how much liquid or gas refrigerant is required to meet user demand
- Sends required liquid or gas refrigerant to indoor units
Indoor evaporator unit
- Transfers energy to and from conditioned area
- Is controlled independently from all other indoor units
- Receives liquid or gas refrigerant, dependent on whether heating or cooling is required