Viessmann SCU345 Manual page 52

Tank cooling
COOl / OSTC
Tank cooling option
Selection: OFF / ON
Factory setting: OFF
When the tank cooling function is activated, the con-
troller aims to cool down the tank during the night in
order to prepare it for solar loading on the following
day.
If the adjusted maximum tank temperature (S1MAX /
S2MAX / S3MAX) is exceeded and the collector
temperature falls below the tank temperature, the
system will be reactivated in order to cool down the
tank.
Reference temperature differences are DT1 (2, 3) O
and DT1 (2, 3) F.
Heat dump
COOL / OHDP
Heat dump
Selection: ON / OFF
Factory setting: OFF
52
COOl / OTCL
Overtemperature collector
Adjustment range: 70 ... 160 °C [150 ... 320 °F]
in steps of 1 °C [2 °F]
Factory setting: 110 °C [230 °F]
COOL / OTPUM
Pump or valve logic
Selection: ON / OFF
Factory setting: OFF
COOL / HDREL
Heat dump relay
Selection: system dependent
Factory setting: 3/4
If the heat dump function OHDP is activated, the se-
lected relay is energized with 100%, if the collector
temperature reaches the adjusted collector overtem-
perature OTCL. If the collector temperature falls by
5 K [10 °Ra] below the adjusted collector overtem-
perature OTCL, the relay will be switched off.
A selection can be made between pump logic and
valve logic (OTPUM ON = pump logic, OTPUM
OFF = valve logic). If pump logic is selected, the relay
for solar loading switches off and the relay for heat
dump remains switched on.
The relay for the heat dump function can be selected
in the HDREL channel.
Note
OTCL
The adjustable value
the collector emergency temperature
by 10 K [20 °Ra]. The heat dump function
will only be available if the collector cooling
function and the system cooling function are
deactivated.
Heat exchange function
DT4 / DT4O
Switch-on temperature diff.
Adjustment range: 1.0 ... 30.0 K [2.0 ... 60.0 °Ra]
in steps of 0.5 K [1.0 °Ra]
Factory setting: 6.0 K [12.0 °Ra]
DT4 / DT4F
Switch-off temperature diff.
Adjustment range: 0.5 ... 29.5 K [1.0 ... 59.0 °Ra]
in steps of 0.5 K [1.0 °Ra]
Factory setting: 4.0 K [8.0 °Ra]
is locked against
CEM