Grant Aerona3 Series - 5 Domestic Hot Water; Temperature Control; Heat Pump Cylinders

Section 5: Domestic Hot WaterPage 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 but you may want to increase or decrease this time period. 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 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. By using the Grant wiring centre, the demand to
space heating circuits is not activated when the DHW demand is present.
To minimise this high temperature period and higher than normal running
costs, ensure that space heating and DHW demand times to not occur
simultaneously.
5.2 Heat Pump 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 Irl has a full range of high efficiency cylinders available from 210ltr to
300ltr in mono and duo wave cylinders.
In order to ensure that a minimum of at least 8K temperature difference is
maintained between cylinder flow and return, the correct Grant IRL heat pump
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.
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 DOMESTIC HOT WATER