Electrical – Grant Products HPAW155 User Manual
8.4 Mains Supply Cable
All Grant Aerona Heat Pumps contain a
3kW immersion element as a boost
heat source. This element will energise
under either one or two conditions :
1. When the external ambient air
temperature drops between -5ºC
and +5ºC. This figure is variable and
adjustable at the ATC.
2. When the heat pump has not seen
a temperature rise of 1ºC or more in
the Return water from the heating
system, in a 20 minute period.
The cable sizing to the heat pump
must include for this additional 3kW
For Bivalent systems where a Gas,
Oil or Wood Pellet boiler is switched
from the heat pump the immersion
heater is disconnected. Refer to
If the boiler is to be used with the
3kW immersion heater still
connected, the additional load must
be taken into account and the
maximum demand must be
determined for each heat pump.
Using the 5m of umbilical cable, connect the controller (right) to the heat pump (left). The controller fits all standard single patresses
(surface and flush). Use one of the cable glands at the rear of the heat pump to protect this cable. To extend (if required) simply splice
a new section into the middle, ensuring all connections are sound and water proof. The size of cable is 0.5mm², and operates at ultra
low voltage (<50Vdc).
Always assume maximum possible
load when considering cable sizing.
The cable supplying power from the
consumer unit to the heat pump must
be connected via an external 2 pole
isolator. This allows the service engineer
to isolate the power supply before
working on the heat pump in safety.
Figure 8-6: Mains supply cable
Figure 8-3: ATC connection
Figure 8-4: Umbilical cable
Figure 8-5: ATC control unit