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Connecting to the heating system
Principle method of operation
The principle method of operation is based on the vapour compression cycle with any additional heat being provided by
the built in electric heater. The control unit controls the heat pump using the outdoor sensor T2 and the flow sensor T1
according to the set heat curve. If the heat pump is unable to meet the heating requirements, the HWDU and the additional
electric heater starts automatically and together with the heat pump provides the required temperature. Hot water is prioritised and controlled by a sensor, T3 in the hot water cylinder. While the DHW is being heated in the hot water cylinder, the
CH production by the heat pump is stopped temporarily through a three-way valve. When the DHW temperature is satisfied
the heat pump continues the CH production.
Operation in extreme cold conditions:
At outdoor temperatures lower than approximately -20, the compressor in the heat pump is switched off and all heating and
hot water heating is via the built in electric heater.
Greensource heat pump and HWDU
E10
C11
C12
G1A
G1B
P11
Q10
Q12
Q13
Radiator system
Expansion vessel
Primary water storage tank*
Radiator pump
Radiator pump
Pressure gauge
Mixing valve
Isolating valve
Water outlet
E20
E21
F21
G2
G3
Q20
Q21
Q22
V21
Heating system
Heat pump
Safety valve
Heating system pump
Fan
3-way valve
3-way valve
Air vent
Filter heating system
E40
C41
E41
V40
W40
F42
Tap water system
Expansion vessel
Hot water cylinder
Hot water
Cold water
Temperature & pressure
relief valve
Isolation valve
Pressure reducing valve
Non return valve
Tundish
Q42
Q43
Q44
Q45
Sensors
T1
T2
T3
T5
T6
T8
T9
T10
T11
T12
Heating system flow
sensor (indoor unit)
Outdoor sensor
DHW sensor
Room sensor
Hot gas sensor
Heat pump flow sensor
(outdoor unit)
Heat pump return sensor
(indoor unit)
Condenser
Evaporator temp.
Air intake
* The drawing above shows the correct connection method for the heat pump where the flow rate around the heating system can fall below 70% of the
nominal flow (i.e. system with zone controls and thermostatic radiator valves). If the heating system has been designed to be fully open at all times then the use
of the primary water storage tank is not required
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