Viessmann SCU345 Manual page 57

Option: Thermal disinfection (OTDIS)
OTDIS
Thermal disinfection function
Adjustment range: ON / OFF
Factory setting: OFF
This function helps to contain the spread of Legionella
in the upper DHW tank zone by systematically acti-
vating the backup heating.
Reference sensor for the thermal disinfection
is the numerically fi rst free sensor! Reference
relay is the numerically fi rst free relay!
OTDES / PDIS
Monitoring period
Adjustment range:
0 ... 30:0 ... 24 (dd:hh)
Factory setting: 01:00
For thermal disinfection, the temperature in the upper
DHW tank zone has to be monitored. This protection
is ensured when, during the monitoring period, the
disinfection temperature is continuously exceeded for
the entire disinfection period.
OTDiS / DDIS
Disinfection period
Adjustment range: 00:00 ... 23:59
Factory setting: 01:00
OTDiS / TDIS
Disinfection temperature
Adjustment range: 0 ... 95 °C [30 ... 200 °F]
in steps of 1 °C [2 °F]
Factory setting: 60 °C [140 °F]
If the thermal disinfection function is activated, the
monitoring period starts as soon as the temperature
at the reference sensor falls below the disinfection
temperature.
When the monitoring period ends, the reference relay
activates the backup heating. The disinfection period
starts to count as soon as the temperature at the al-
located sensor exceeds the disinfection temperature.
If the temperature at the reference sensor exceeds
the disinfection temperature by more than 5 K, the
reference relay switches off until the temperature has
fallen below a value of 2 K [4 °Ra] above the disinfec-
tion temperature.
Thermal disinfection can only be completed when the
disinfection temperature is exceeded for the duration
of the disinfection period without interruption.
If the disinfection conditions have been fulfi lled by
solar loading before the monitoring period ends, ther-
mal disinfection is considered complete and a new
monitoring period begins.
Note
If the thermal disinfection option OTDIS
is activated, the display channels TDIS and
CDIS will be displayed. TDIS will be dis-
played regardless of the temperature meas-
ured at the reference sensor.
Due to the fl exible control logic, the exact time of
thermal disinfection is not predictable. In order to set
a fi xed time for the disinfection, the starting delay can
be used.
Thermal disinfection with starting delay
OTDIS / SDIS
Starting time
Adjustment range:
0:00 ... 24:00
Factory setting: 00:00
full hours only
When a starting time for thermal disinfection with
starting delay is adjusted, backup heating activation
will be delayed until that time, even after the monitor-
ing period has ended.
If the monitoring period ends, for example, at 12:00
o'clock, and the starting time has been set to 18:00,
the reference relay will be energized with a delay of 6
hours at 18:00 instead of 12:00 o'clock.
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