Introduction to VRV / VRF
Variable Refrigerant Volume or Variable Refrigerant Flow (depending on manufacturer) has been around or about a quarter of a century. The basic idea is that a large outdoor unit serves multiple indoor units. Each indoor unit uses an LEV (electronic liquid expansion valve) to control its refrigerant supply to match the demand of the space it serves. The outdoor unit also varies its output to match the communal demands of the indoor units it serves. Thus, at any point in a system there will be a variable volume of refrigerant flowing. Various strategies are used to vary the output of the outdoor units including;
• Modulating fan/s
• Heat exchanger valved in sections
• Variable speed inverter drive compressor/s
• Multiple compressors
• Twin or multiple modular outdoor units
Outdoor unit capacities range from around 14 kW to over 100 kW. Indoor units cover the full range of DX models normally available.
System types
VRV/VRF systems can be used for cooling only, heat pumping and heat recovery. On heat pump models indoor units can be in either mode but all must be in the same mode if served by the same out door unit. The cooling only and heat pump models are basically large, sophisticated, efficient multi-splits. The heat recovery or simultaneous mode systems provide both heating and cooling from the same outdoor unit and thus exploit this technology most effectively. They offer considerable potential for energy savings in many applications.
System types
VRV/VRF systems can be used for cooling only, heat pumping and heat recovery. On heat pump models indoor units can be in either mode but all must be in the same mode if served by the same out door unit. The cooling only and heat pump models are basically large, sophisticated, efficient multi-splits. The heat recovery or simultaneous mode systems provide both heating and cooling from the same outdoor unit and thus exploit this technology most effectively. They offer considerable potential for energy savings in many applications.
great article Heating and Cooling Mississauga
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