For all its merits, the traditional split and multi-split systems have several disadvantages, significantly limiting their use. In the first place it is a small length of interblock communications, usually not more than 20 meters; at such length reducing the power conditioner 30 percent is not to be avoided. Another disadvantage of the multi-split systems is a limited quantity of indoor units, usually from two to four pieces. All this leads to the fact that the air conditioning of an elite apartment or cottage several external units which do not want to "fit" in the architect's design are to be placed outside (sometimes even on the facade).
Until recently there has been the only way out of the situation - to mount one channel air-conditioner with the distribution of cooling air duct system located above the false ceiling. Besides reducing useful height of the rooms to 15 - 20 cm (the diameter of the heat-insulated ducts), this solution had one more major drawback - the air temperature control was possible only all over the place in general, as one indoor unit did not allow to fix its own temperature in each room. The solution was found in 1982, when the company Daikin introduced the first world's VRV air conditioning system.
Characteristics and features of VRV systems
* As in the multi-split systems, single outdoor unit can be connected to a number of internal, but in a VRV system its number could reach several tens.
* As in some multi-split systems, VRV indoor units can be of different types (wall, channel, cartridge, etc.) and have different capacity, usually from 2 to 25 kW.
However, VRV systems have some fundamental differences from all previously manufactured air conditioners:
* A separate Freon line between the external and internal units is laid in common multi-split systems. In VRV systems all units are connected to a single system of pipelines, that means the total track of two or three copper pipes connected to 30 indoor and 3 outdoor units. This solution allows to simplify (to reduce the cost and accelerate) the installation, and also makes it easy to expand the system in the future.
* The maximum distance between the indoor and outdoor unit (pipe length) makes 100 meters. Height drop between outdoor and indoor units (the vertical distance between the blocks) is 50 meters. So it was possible to place the outdoor unit in any convenient location - on the roof, in the basement, or even a few dozen meters from the house.
* The indoor units management can be inplemented both by individual wireless remotes (as in the common multi-split systems), and with a centralized management console that controls operating conditions of all the indoor units and the state of the system. Besides, VRV system can be managed from a PC.
* As compared with common air conditioners, VRV indoor units support the fixed temperature with pinpoint accuracy - up to ± 0,5 ° C.
The name “Variable Refrigerant Volume” reflects the main difference of VRV system from the rest of the air conditioning systems – using a single system of pipelines. In VRV systems each indoor unit has an electronic expansion valve, which regulates the amount of refrigerant supplied from a common route, depending on the heat load on the block. Thanks to this VRV system supports the fixed temperature more evenly without drop inherent the common air conditioners which regulate the air temperature by periodically switching on and off.Besides Daikin, nowadays such systems are produced by Mitsubishi Heavy, Mitsubishi Electric, Sanyo, Toshiba, Fujitsu General and others. So long as the name “VRV” is a registered trademark of Daikin, the name “Variable Refrigerant Flow” has been cosen to refer to the similar systems from other manufacturers. That means the same as the VRV (VRF means a class or type of the air conditioners). The difference between the VRF systems of different manufacturers is not very significant and is determined by the quantity of the connected units, the maximum length of the route, ease of the operation, reliability and the service life.