EVI technology are designed for highly efficient heat generation in cold climates and air conditioning in hot weather.

Due to the presence of an additional injection circuit, EVI type of heat pump can operate at temperatures from -30°C with a conversion factor (COP) of 2. At higher temperatures, the COP reaches 4.7. Such characteristics allow us to talk about the use of heat pumps as the main source of heat supply throughout the year. The heat pump is easily and inexpensively integrated into the finished heating system (boilers of various types), allowing you to reduce heating costs by 2-3 times. Thanks to the use of a DC inverter circuit, heat pumps can change the heating or cooling power depending on the consumer’s request. This gives an additional increase in the heating conversion ratio (COP) and conditioning (EER).

COP (efficiency) of air-to-water heat pumps is subject  of surrounding air temperature fluctuations. Standard heat pumps can ensure that the temperature difference between the heat source (outside air) and the supply water to the heating system is no more than 60°C. This means that for an air source heat pump, at an outdoor air temperature of -15 °C, the maximum water supply temperature does not exceed 45 °C. With radiator heating, this water temperature may not be sufficient.

To solve this problem, a simple, but very effective solution was adopted.

An additional heat exchanger has been added to the working fluid circuit and

thermal expansion valve (TRV). Part of the refrigerant (from 10 to 25%), after the condenser, is taken to an additional circuit with an expansion valve. In the valve, the working fluid is expanded and then sent to an additional heat exchanger. Additional heat exchanger functions are evaporation of refrigerant. The low temperature steam injected directly into the compressor. Compressors are equipped with another input. Such type of compressors are called EVI(intermediate vapor injection) compressors.

This process occurs during the second part of the compression of the vaporized refrigerant.

Main refrigerant flow is overcooled by 8-12°C and enters the evaporator with a lower temperature. This allows you to absorb more natural heat.

Due to these processes, there is a “shift” of temperature. EVI technology significantly improves the efficiency of the heat pump.

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