Viessmann VITOLIGNO 300-C Installation And Service Instructions Manual page 177

Control functions
(cont.)
Functions
Reheating suppression with solar circuit
If a solar circuit is installed, reheating suppression of
the heating water buffer cylinder can be selected.
The reheating suppression changes the required set
value ("Set system temperature
water buffer cylinder in case of solar charging
(code 33).
The changed "Set system temperature
the heating water buffer cylinder has sufficient capacity
for the solar circuit.
Control sequence (with heating water buffer cylin-
der)
Start
The boiler starts if the "Set system temperature
the selected buffer temperature sensor ("boiler start
sensor", coding address 39) is undershot.
Solar circuit control
The solar circuit pump is controlled via the differential
temperature between the solar circuit and DHW heat-
ing (code 6E). If the differential temperature between
the solar circuit and the DHW is above the set value,
the solar thermal system activates the pump and mixer
for heating DHW. The actual collector temperature
must be sufficient.
Heating circuit control unit
The heating circuit flow temperature is captured by the
flow temperature sensor.
The set flow temperature of each heating circuit is
■
determined from the following parameters:
Outside temperature
–
– Set room temperature
– Operating mode
– Heating curve slope and level
■ The flow temperature is regulated by the stepped
opening or closing of the mixers.
The mixer motor control changes the actuating and
pause times subject to the control differential (control
deviation).
■ Coding addresses that influence the heating circuit
control unit:
A0 to FB
For a description, see codes overview
Set system temperature = highest temperature demanded by all control circuits (heating circuits, DHW heating)
*12
Actual buffer temperature = actual temperature value (currently present temperature) of the heating water buffer cylinder
*11
Set buffer temperature = set temperature for the heating water buffer cylinder
*10
*12 ") of the heating
*12 " ensures that
" at
*12
Control mode
The boiler combustion output is reduced if the "Actual
buffer temperature " "Set buffer temperature
*11 ≥
Shutdown
The boiler heats the heating water buffer cylinder until
the selected temperature ("Buffer cylinder charging up
to temperature", code 37) at the selected buffer tem-
perature sensor ("Buffer cylinder charging up to sen-
sor", code 36) is reached.
DHW is heated until the following conditions are met:
■ Max. DHW temperature (code 6F) is reached.
or
Differential temperature between solar thermal sys-
■
tem and DHW heating (code 6E) is less than the set
value.
Functions
The heating circuit flow temperature is captured by the
flow temperature sensor.
Time program
In accordance with the times programmed in the
"Heating" program, the control unit time switch regu-
lates between central heating with standard room tem-
perature and central heating with reduced room tem-
perature.
Every operating mode has its own set level.
Outside temperature
A heating curve must be set to adjust the control unit
to the building and the heating system. See chapter
"Adjusting heating curves"
Function description
" .
*10
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