7
FOR THE USER
The route of the refrigerant through the heat pump in heat radiator mode
In
the evaporator
(heat exchanger)
the refrigerant meets the outdoor air. The air is drawn through the evapora-
tor by a fan located on top of the heat pump. The refrigerant, which was previously in a liquid state, will evaporate
in this process. The pressure is low and heat is required. Heat is taken from the outdoor air. A sensor in the
expansion valve (6) ensures the evaporator utilises as much of the “free energy” as possible before the refrigerant
(in a gas state) is led into the compressor.
In
the compressor
the pressure of the refrigerant increases. The temperature of the vapour reaches approxi-
100ºC. The warm gas is then led into the condenser.
The condenser
is the heat pump’s heat emitting part. In the condenser, which is a fully soldered heat exchanger
in stainless steel, the refrigerant (gas state) meets the water from the heating system (radiators and fl oor coils).
When the warm gas is cooled by the circulating heating water, it changes into a liquid state (condenses). Energy
is emitted in this process to the heating system or hot water. After the condenser, the refrigerant, which is now in
liquid form, continues through a drying fi lter.
The dr ying fi lter
is used to collect any moisture in the system. After the fi lter, the refrigerant passes through a
sight glass.
The sight glass
is used to check the fl uid level in the system. There should be no bubbles in the sight glass
during normal operations. However, there might be bubbles when the heat pump is started and stopped or during
defrosting. After the sight glass, the refrigerant continues on to an expansion valve.
In
the expansion valve
the pressure of the refrigerant drops. This also causes the temperature to drop. When
the refrigerant has left the valve and passes the evaporator it changes to vapour again. This completes the
refrigerant circuit. The expansion valve is equipped with a sensor (bulb) just before the compressor. The sensor
controls the amount of fl uid entering the evaporator.
1
2
3
4
5
6
1
2
3
4
5
6
Heat transfer fl uid out
Heat transfer fl uid in
Refrigerant fl ow in heat rad.
mode
Refrigerant fl ow in defrosting
mode
Service
conn.
Non-return
valve
Suction accumulator
Bulb
Low pressure
switch
Service
conn.
High pressure
switch
Four-way
valve
How a heat pump works
Service
conn.
