On/Off Control

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