Viessmann SCU345 Manual page 44

LOAD(1, 2, 3) / DT1(2, 3) F
Switch-off temperature diff.
Adjustment range: 0.5 ... 49.5 K [1.0 ... 89.0 °Ra]
in steps of 0.5 K [1.0 °Ra]
Factory setting: 4.0 K [8.0 °Ra]
Note
The switch-on temperature difference must
be at least 0.5 K [1.0 °Ra] higher than the
switch-off temperature difference. The set
temperature difference must be at least
0.5 K [1.0 °Ra] higher than the switch-on
temperature difference.
Speed control
LOAD(1, 2, 3) / DT1(2, 3) S
Set temperature difference
Adjustment range: 1.5 ... 50.0 K [3.0 ... 90.0 °Ra]
in steps of 0.5 K [1.0 °Ra]
Factory setting: 10.0 K [20.0 °Ra]
Note
To enable speed control, the corresponding
relay has to be set to "Auto" (adjustment
channel MAN) and the pump control type
has to be set to Puls, or ADAP (adjustment
channel PUMP).
44
LOAD(1, 2, 3) / RIS(1, 2, 3)
Rise
Adjustment range: 1 ... 20 K [2 ... 40 °Ra]
in steps of 1 K [2 °Ra]
Factory setting: 2 K [4 °Ra]
When the switch-on temperature difference is
reached, the pump is activated at 100% speed for 10 s.
Then, the speed is reduced to the minimum pump
speed value.
If the temperature difference reaches the adjusted
nominal value (DT S), the pump speed increases by
one step (10 %). The response of the controller can
be adapted via the parameter "Rise". If the difference
increases by the adjustable rise value RIS, the pump
speed increases by 10 % until the maximum pump
speed of 100 % is reached. If, at decreasing tempera-
tures, the temperature difference decreases by the
adjustable rise value RIS, the pump speed decreases
by 10 %.
Maximum tank temperature
LOAD(1, 2, 3) / S1(2, 3) MAX
Maximum tank temperature
Adjustment range: 4 ... 95 °C [40 ... 200 °F]
in steps of 1 °C [2 °F]
Factory setting: 60 °C [140 °F]
If the tank temperature reaches the adjusted maxi-
mum temperature, the tank will no longer be loaded
in order to avoid damage caused by overheating. The
symbol is shown on the display if the tank tem-
perature exceeds the maximum value.
The corresponding reference sensor can be chosen,
see "Sensor maximum tank temperature".
Switch-on hysteresis -2 K [-4 °Ra]
Sensor maximum tank temperature
LOAD(1, 2) / SMXS1 (2)
Sensor tank maximum temp.
Adjustment range:
1st tank: S2, S3
2nd tank: S4, S5
Tank being loaded vertically: S2, S3
Factory setting:
1st tank: S2
2nd tank: S4
Sensor allocation for the tank maximum limitation.
The maximum limitation always refers to the sensor
selected.
If e. g. S3 is selected, the differential control will still
be carried out using S1 and S2. The temperature at S2
can exceed the adjusted limit temperature, the system
will not switch off. If the value at S3 reaches the limit
temperature, the system will be switched off.
Note
In 3-tank systems, the reference sensor can
only be selected for the numerically 1st tank.