Adjustment Channels - Viessmann SCU224 User Manual

SCU224

4.2 Adjustment channels

System layout selection
Arr:
System layout selection.
Adjustment range: 1 ... 10
Factory setting: 1
Security enquiry:
∆T -regulation
DT O / DT1O / DT2O /
DT3O:
Switch-on temperature diff.
Adjustment range: 2.0 ... 40.0°Ra
[1.0 ... 20.0 K]
in steps of 1 °Ra [0.5 K]
Factory setting: 12.0°Ra
[6.0 K]
DT F / DT1F / DT2F / DT3F:
Switch-off temperature diff.
Adjustment range: 1.0 ... 39.0°Ra
[0.5 ... 19.5 K]
in steps of 1 °Ra [0.5 K]
Factory setting: 8.0°Ra
[4.0 K]
Pump speed control
DT S / DT1S / DT2S / DT3S:
Nominal temperature difference
Adjustment range: 3.0 ... 60.0 °Ra
[1.5 ... 30.0 K]
in steps of 1 °Ra [0.5 K]
Factory setting: 20.0 °Ra
[10.0 K]
RIS / RIS1 / RIS2 / RIS3:
Rise
Adjustment range:
2 ... 40 °Ra [1 ... 20 K]
in steps of 2 °Ra [1 K]
Factory setting: 4 °Ra [2 K]
Minimum pump speed
nMN, n1MN, n2MN:
Pump speed control
Adjustment range:
30 ... 100
in steps of 5 %
Factory setting: 30
In this channel, a pre-defined system layout can be selected.
Each system layout has a set of pre-programmed settings
that can be individually changed.
If the system layout selection is changed later on, all adjust-
ments made in the other channels will be lost. Therefore,
changing the system layout is always followed by a security
enquiry.
Only confirm the security enquiry if you are sure that
you wish to change the system layout selection!
Î To confirm the security enquiry, press button 3
The controller works as a standard differential controller. If
the switch-on difference is reached, the pump is activated.
When the temperature difference falls below the adjusted
switch-off temperature difference, the respective relay
switches off.
Note:
The switch-on temperature difference must be
at least 1 °Ra [0.5 K] higher than the switch-off
tempe rature difference.
Note:
When the drainback option ODB is activated,
the temperature differences DT O, DT F and
DT S are set to a fixed adjustment:
DT O =
DT F =
DT S =
Previous adjustments made in these channels will
be overridden and may have to be entered again if
ODB is deactivated later on.
Note:
For pump speed control, the operation mode
of the corresponding relay must be set to Auto
(adjustment channel MAN1 / MAN2)
When the switch-on temperature difference is reached,
the pump is activated at full speed for 10 seconds. Then, the
speed is reduced to the minimum pump speed value (factory
setting = 30 %).
If the temperature difference reaches the adjusted nominal
temperature difference, the pump speed increases by one
step (10 %). If the difference increases by the adjustable rise
value, the pump speed increases by 10 % respectively until the
maximum pump speed of 100 % is reached. The response of
the controller can be adapted via the parameter "Rise".
Note:
The nominal temperature difference must be
at least 1 °Ra [0.5 K] higher than the switch-on
tempe rature difference.
A relative minimum pump speed can be allocated to the
outputs R1 and R2 via the adjustment channels nMN,
n1MN and n2MN.
Note:
When loads which are not speed-controlled (e.g.
valves) are used, the value must be set to 100 % in
order to deactivate pump speed control.
20 °Ra [10 K]
8 °Ra [4 K]
30 °Ra [15 K]
39
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