Bosch WORCESTER GREENSTORE User Manual download pdf (Page 6)

Heat transfer ﬂ uid in. The heat pump collects stored solar energy. It contains a heat transfer ﬂ uid which is a

solution of water and glycol. This antifreeze mixture collects the heat from the earth or rock and is fed into

the evaporator. The temperature is on average around 3-5ºC.

In the evaporator, the heat transfer ﬂ uid meets the refrigerant. At this stage, the refrigerant is in a ﬂ uid state

and is at approximately -10ºC. When the refrigerant meets the heat transfer ﬂ uid it starts to boil. It then forms

a vapour, which is fed into the compressor. The temperature of the vapour is around 0ºC.

The pressure of the refrigerant increases in the compressor and the vapour temperature rises from 0ºC to

approximately +125ºC. The hot gas is then forced into the condenser.

The condenser transfers the heat to the heating system (underﬂ oor heating or perhaps radiators) and the hot

water system. The vapour is cooled in the condenser and becomes liquid. The pressure in the refrigerant is

still high when it reaches the expansion valve.

The refrigerant pressure is lowered in the expansion valve. At the same time, the temperature also drops to

approximately -10ºC. When the refrigerant passes the valve and the evaporator it changes to vapour again.

The expansion valve also regulates the amount of refrigerant fed into the evaporator.

The heat transfer ﬂ uid is led out from the heat pump to the ground loop to collect new stored solar energy.

The temperature of the ﬂ uid is approximately 3ºC cooler than the ﬂ ow in.

Underﬂ oor heating

Radiator

Fan-assisted

radiator

Heat pump

Rock

Soil

0ºC

-3ºC

0ºC +100ºC

-10ºC

2 3 4

Heating system

pump

Heat transfer ﬂ uid

pump

How the heat pump works

The heating circuit

The collector circuit

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Bosch WORCESTER GREENSTORE User Manual Page 6