Viessmann VITOTRONIC 100 Installation And Service Instructions Manual page 126

Function description
Cylinder temperature control
Code "55:2":
Cylinder temperature control with
2 cylinder temperature sensors
Cylinder temperature sensor 1
enables the cylinder primary pump,
and is evaluated for stop conditions
during the pump run−on time.
Cylinder temperature sensor 2
(inside the cold water inlet) is
designed to start cylinder heating
prematurely when large volumes of
DHW are drawn off as well as to stop
cylinder heating prematurely, if no
DHW is drawn.
Select starting and stopping points
via coding addresses "68" and "69".
Code "55:3"
Cylinder thermostat
storage system
DHW cylinder goes cold
(set value 2.5 K; adjustable via
coding address "59"),
H The set boiler water temperature is
adjusted 20 K higher than the set
DHW temperature (adjustable via
coding address "60").
H The cylinder primary pump is
switched ON.
126
(only for single boiler systems) (cont.)
cylinder
H The three−way mixing valve opens
and then regulates to the defaulted
set value.
H The cylinder primary pump cycles
(short term ON and OFF) until the
set flow temperature has been
reached (set DHW temperature
+ 5 K), then it runs constantly.
If, during cylinder heating, the
actual value stays below the
required set temperature, then the
cylinder primary pump will
temporarily cycle again.
The DHW cylinder is hot
Cylinder temperature sensor 1:
Actual valueyset value
and
Cylinder temperature sensor 2:
Actual value > set value 1.5 K)
H The set boiler water temperature is
reset to the weather−compensated
value,
H The cylinder primary pump is
switched OFF:
Immediately, if the three−way
mixing valve is fully open
or
after expiry of a run−on time
adjustable via code "62".