133
Function of the ON/OFF switch on the control unit
Fig. 76
The
ON/OFF switch on control unit
A
and the reset
button (green) for high limit safety cut-out
B
is located
behind the cover.
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.
Note
Do not operate the ON/OFF switch on the control unit
if the boiler is running.
Control functions
Heating water buffer cylinder
The heating water buffer cylinder is used to store
excess energy from heat generators.
The buffer charging level is detected by buffer temper-
ature sensors. The control unit uses the buffer charg-
ing level 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
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
Display and controls
(cont.)
5679249
Functions
