Viessmann Vitoligno 300-C Installation And Service Instructions Manual page 155

Display and control elements
Function of the ON/OFF switch on the control unit
Fig. 80
Control functions
Heating water buffer cylinder
The heating water buffer cylinder is used to store
excess energy from heat generators.
The buffer charging condition is detected by buffer
temperature sensors. The control unit uses the buffer
charging condition to calculate the set value for the
combustion output of the boiler.
Optimum settings of the heating system have a posi-
tive effect on the service life and efficiency of the
boiler. Positive influencing factors are:
■ Low start-up frequency
High combustion output
■
Guideline values for load operation
80 % full load
–
– 20 % partial load
■ Longest possible runtime of the boiler (no cycling).
A boiler runtime of at least 1 hour with the highest
possible boiler output should be achieved.
The set temperature of the heating water buffer cylin-
der depends on the following parameters:
■ Outside temperature
■ "Buffer" heating curve (slope and level)
■ "Buffer" operating mode
(cont.)
The ON/OFF switch on control unit
button (green) for high limit safety cut-out
behind the cover.
Note
Do not operate the ON/OFF switch on the control unit
if the boiler is running.
Note
■ Matching the heating curve ("Buffer") to the volume
of the heating water buffer cylinder prevents cycling
of the boiler.
Standard values
■
Small heating water buffer cylinder
–
Low level of heating curve indicates early modulat-
ing.
– Large heating water buffer cylinder
High level of heating curve indicates late to no
modulating.
Function description
Danger
Touching live components can result in life
threatening injuries. After switching off the
ON/OFF switch on the control unit, there are still
live components inside the control unit enclo-
sure.
■ Isolate the system from the power supply, e.g.
by removing the separate fuse or by means of
a mains isolator, and check that it is no longer
live.
■ Safeguard the system against reconnection.
and the reset
A
is located
B
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