In regime 'Heating' the heat from the sun warms the input buffer (position 2 of the three-way valve). The thermopump does not consume underground water, just the warm buffer water through the circulation pump. The microprocessor controller monitors the buffer and underground water temperatures. When the buffer temperature becomes "<" or "=" to the underground water temperature, the water changing pump switches on and the circulation pump switches off. The work continues with the underground water heat, until sun warmth is received (work throughout the night or when there is insufficient sun)
In regime 'Cooling' the sun heats up the boiler (position 1 of the three-way valve) together with the thermopump. Moreover, in case of heat excess from the sun collector, the thermopump control switches between the three-way valves and the heat is discarded together with the processed water in the input buffer.