Viessmann SCU224 User Manual page 40

SCU224
Maximum tank temperature
S MX / S1MX / S2MX:
Maximum tank temp.
Adjustment range:
40 ... 200 °F [4 ... 95 °C]
Arr 10:
40 ... 190 °F [4 ... 90 °C]
in steps of 2 °Ra [1 K]
Factory setting:140 °F [60 °C]
Collector temperature limitation
Emergency shutdown of the collector
EM / EM1 / EM2:
Collector temperature limitation
Adjustment range:
170 ... 390 °F
[80 ... 200 °C]
in steps of 2 °Ra [1 K]
Factory setting:
270 °F [130 °C]
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Once the adjusted maximum temperature is exceeded,
the solar pump is switched off and further loading of the
tank is prevented to reduce scald risk or system damage. A
fixed hysteresis of 4 °Ra [2 K] is set for the maximum tank
temperature.
When the temperature at the corresponding sensor exceeds
the adjusted maximum tank temperature, the
shown on the display.
Note:
If the collector cooling or the system cooling
function is activated, the adjusted tank tempe-
rature may be overridden. In order to prevent
system damage, the controller is also equipped
with a non-adjustable emergency shutdown if the
tank reaches 200 °F [95 °C].
If the adjusted collector emergency shutdown temperature
(EM / EM1 / EM2) is exceeded, the controller switches off
the solar pump (R1 / R2) in order to protect the system
against overheating (collector emergency shutdown).
A hysteresis of 20 °Ra [10 K] is set for the collector
temperature limitation. While the collector is in emergency
shutdown, (flashing) is shown on the display.
Note:
If the drainback option ODB is activated,
the adjustment range of EM is changed to
170 ... 250 °F [80 ... 120°C]. The factory setting
in that case is 200 °F [95 °C].
WARNING! Danger of injury and system da-
mage through pressure surges!
If water is used as a heat transfer
medium in a pressure-less system,
the water will start boiling at 212 °F
[100 °C].
Î If a pressure-less drainback
system is used with water as a
heat transfer medium, do not
adjust the collector tempera-
ture limitation EM to more
than 200 °F [95 °C]!
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