Grant Products HPAW155 - Manual (Page 29)

Electrical
25
8.9 Extending the Electrics
It may be part of the system design to
incorporate Solar Thermal into the
design.
This is easily done with the use of an
additional two-pole relay. Following the
diagram in Figure 8-13 below will give
the solar thermal system a priority over
the heat pump when there is a demand
for DHW only.
This can, of course be added to both
monovalent and bivalent systems. It is
much easier to carry out all these types
of systems based on S-plan type
controls only.
Y and W type plans can be used, but
the need for additional relays is not
practical. It is much easier to convert Y
and W type plans to S types from the
start.
8.8 Bivalent Systems
For bivalent systems, it is necessary to
disconnect the internal immersion
element from the relay inside the heat
pump control panel. Taking the live and
neutral outputs from this relay extend
this wire to the boiler. Isolate this cable
through a fused double pole spur
switch and mark on the switch that the
supply comes from the heat pump.
Follow the wiring diagram as shown in
Figure 8-11 for a bivalent system.
MCB
230V
50Hz
L N E 4 5 6 7 8 9 10
1
Limit
2
c
1
Control
2
c
Programmer
Heating
zone
valve
CH HW
Fuse
Fuse
L
Off
O
Bl
Br
Gr
Off
O
Bl
Br
Gr
DHW
Zone Valve
Relay 3
N
1 3
Room
Thermostat
Cylinder Thermostat
L
N
E
E
N
L
In
Out
Solar
pump
Solar controller
Panel
sensor
Cylinder
sensor
2
Figure 8-14: Connection diagram for Grant solar thermal system
C CH HW
1 2 3
Heat pump
S-Plan controls
connections
IMPORTANT
Do not take the Neutral from the heat pump to feed the boiler circuit. This will create
an imbalance at the MCB and cause nuisance tripping. Always take the neutral
supply from the existing S-Plan wiring centre.