The on/ off control admits a higher control deviation (equal to the P-band), but reduces the number of switching of the charging pump. The domestic hot water temperature setpoint is defined as shown in the table below:
Table 5. On/Off Control
DHW setpoint |
Condition |
DHW_TempSp |
Auto operation - time schedule DHW_TempSp >= SYS-01: occupied setpoint. DHW_TempSp < SYS-01: un-occupied setpoint |
parameter DEX-01 |
DHW setpoint during extended operation |
parameter LEG-01 |
DHW setpoint during anti-legionella operation |
According to the currently-valid Drinking Water Guidelines, the DHW setpoint should be at least 65 °C, to guarantee a minimum DHW temperature of 50 °C.
If you set the charging control P-band UWT-01 to a lower value, e.g. 2.5 K, you can reduce the setpoint by the same amount = 62,5 °C.
The calculated setpoint can be increased by the:
On/ Off Control with Buffer Upper Sensor
The domestic hot water buffer temperature control
On/ Off Control with Buffer Upper and Lower Sensor
The domestic hot water buffer temperature control:
Fig. 4. DHW On/Off Control
Table 6. Parameter List
Description |
Range |
Default |
Units |
UWT-01: P-band buffer temperature control |
1...20 |
5 |
K |
SST-01: temp. difference primary/ secondary system |
0...60 |
10 |
K |