The Heat Pump; Function Description - Danfoss DHP-AX Installation And Service Instructions Manual

11

The heat pump

11.1

Function description

In order for the heat pump to be able to retrieve heating energy from the outdoor air and transfer it to the
heating system of the house, two separate circuits are required. The figure below shows the different circuits
and how they work together in the transfer of heating energy.
Water
Expansion valve/
pressure drop
Enclosed
refrigerant
1 A fan draws up the outdoor air through an air heat exchanger, which heats up the cold refrigerant, which
evaporates into a gas. The energy produced during this process is retrieved from the passing outdoor air.
2 The refrigerant that now supplies energy in the form of heat is transferred to the compressor, which both
increases its temperature and pressure.
3 The extremely hot refrigerant continues to the condenser. Here, the refrigerant is cooled and releases
its heating energy to the heating system. The refrigerant's temperature drops and condenses to a liquid
state.
4 The heating system transports the heating energy out to the water heater or the heating system, which
indirectly heats the house.
5 The refrigerant is then transported through the expansion valve where the pressure and temperature
drop and the process starts again.
A heat pump utilises the free energy from the sun and that is found in a natural heat
source, such as rock, ground, ground water or air. The heat pump can be compared
to a reversed refrigerator; in a refrigerator heat is transferred from the inside of the
refrigerator to the outside, whereas in a heat pump, the stored solar energy that is
stored in a heat source is transferred to the inside of the house. The heat pump uses
the solar energy in the heat source and gives back two to three times more heat
energy than it uses in electrical energy. The heat pump is, therefore, a very environ-
mentally friendly and economical way of heating a house.
Figure 14: The relationship between consumed electrical energy and free solar energy.
Heating system and
water heater
Condenser
3
Compressor/
5
pressure increasing
1
Fan
Outdoor air
Figure 15: Function principles of a heat pump.
VMBMH302
4
Heating system – is the circuit that contains
the water that transports the heat/energy to
the heating system and the water heater.
Refrigerant circuit – is the circuit that con-
tains a chlorine and freon free refrigerant that
inside the heat pump, transfers the retrieved
2
heat energy to the heating system through
evaporation, compression and condensation.
Air heat exchanger
Service – 21