Grant Aerona 3 HPID10R32, Instructions Manual, Page: 20 / 100

Page 20
5.1 TEMPERATURE CONTROL
If a DHW demand is made, the heat pump will continue to provide
space heating for a minimum period of 15 minutes (parameter 3122
- refer to Table 5-1). If space heating is already being demanded
and has been on for this minimum period, then the heat pump will
change over to prioritise DHW.
In either case, once DHW is being provided, the flow temperature
will target 55°C, irrespective of the space heating target
temperature. Also note that there is no weather compensation
control when in DHW mode.
The time limit for DHW can be set using parameter 3121. The
default setting is 60 minutes. After this time period has been
reached, the heat pump will default back to the original demand that
was in place prior to the DHW demand or to a stand by state if the
change is demand state occurred during the DHW demand.
If the unit times out on parameter 3121, remember the motorised
valve of the DHW circuit will remain open as it is controlled by
the cylinder thermostat and not the heat pump and will not heat
up to the correct temperature when using the space heating flow
temperature. It is also possible that the cylinder could be robbed of
heat to the space heating circuit if the stored water is hotter than the
flow temperature to the space heating circuit.
If the motorised valve for space heating is open during DHW
demand, the 55°C flow temperature will also enter the space
heating circuit, increasing the recovery time of the cylinder.
To minimise this high temperature period and higher than normal
running costs, ensure that space heating and DHW demand times
to not occur simultaneously.
5 Domestic Hot Water
Table 5-1: DHW and space heating parameters
Level
Parameter
Function description
Display and input value
Remarks
Group Code Default Min. Max. Unit
I 31 21 Maximum time for DHW request 60 0 900 1 min
I 31 22 Minimum time for space heating 15 0 900 1 min
For details of how to access the parameter settings, refer to Section 9.3.
5.2 QUICK RECOVERY CYLINDERS
As the water temperature from the heat pump is lower than from
a traditional system using a boiler, a much larger coil is required
inside the cylinder to transfer the heat efficiently.
Grant UK has developed a range of “Quick Recovery” hot water
cylinders for use with a heat pump.
In order to ensure that a minimum of at least 8K temperature
difference is maintained between cylinder flow and return, the
correct Grant UK Quick Recovery cylinder must be selected to
match the heat pump output.
Failure to use the correct cylinder can result in a reduced heat
transfer in the cylinder and a lower temperature differential.
Section 5: Domestic Hot Water