Viessmann VITOTRONIC 200 Installation And Service Instructions Manual page 64

Function Description, Vitotronic 200/300-K
DHW Tank Temperature Control
System with tank loading system
The above functions also apply in conjunction with tank
loading systems.
Set the following coding: "55:3" in the "DHW" group;
"4c:1", "4e: 2" in the "General" group.
System with solar control unit
A third set DHW temperature can be assigned at coding
"67" in the "DHW" group.
The DHW tank is only reheated by the boiler if the
temperature falls below this value.
Control sequence
Coding "55:0" in the "DHW" group;
tank heating
The DHW tank goes cold (set value -5°F (-2.5 K);
change at coding "59"):
H The common set supply temperature is set 36°F (20 K)
higher than the set DHW temperature (change at coding
"60").
The DHW tank is hot [set value +5°F (+2.5 K)]:
H The common set supply temperature is returned to the
set weather-compensated value.
H DHW pump delay off:
The DHW pump continues to run on after tank heating
until one of the following criteria is met:
– The weather-compensated set supply temperature
has been reached.
– The set DHW temperature is exceeded by 9°F (5 K).
– The set max. delay off time is reached (coding "62").
H Without pump delay off (coding "62:0")
Coding "55:1" in the "DHW" group;
adaptive tank heating
With adaptive tank heating, the speed of the temperature
rise during DHW heating is taken into account.
The DHW tank goes cold [set value -5°F (-2.5 K); change
at coding "59"]:
H The common set supply temperature is set 36°F (20 K)
higher than the set DHW temperature (change at coding
"60").
The DHW tank is hot:
H The control unit checks whether the boiler will be
required to supply heating energy after the tank has
been heated up or whether residual boiler heat should
be transferred to the DHW tank.
Accordingly, the control unit determines the burner and
circulation pump stop times to prevent the set DHW
temperature being substantially exceeded after the
tank has been heated up.
64
Vitotronic 200, HO1B and 300-K, MW2C Installation/Service
(continued)
Coding "55:2" in the "DHW" group;
tank temperature control with 2 tank temperature sensors
Tank temperature sensor 1 enables the DHW pump for
tank heating and is evaluated for stop conditions during
the pump delay off time.
Tank temperature sensor 2:
Tank heating will start early if a lot of hot water is drawn
off. Tank heating will terminate early if no hot water is
drawn off.
DHW tank goes cold:
H Set value -5°F (-2.5 K), change at coding "59"
or
H Actual DHW temperature at sensor 2 < set DHW
temperature x factor for start time (adjustment at
coding "69")
The DHW tank is hot:
H set value +5°F (+2.5 K)
and
H Actual DHW temperature at sensor 2 > set DHW
temperature x factor for stop time (adjustment at
coding "68")
Coding "55:3" in the "DHW" group;
tank temperature control tank loading system
The DHW tank goes cold [set value -5°F (-2.5 K); change
at coding "59"]:
H The common set supply temperature is set 36°F (20 K)
higher than the set DHW temperature (change at coding
"60").
H The primary pump in the tank loading system starts.
H The 3-way mixing valve opens and then regulates to the
specified set value.
H The circulation pump for tank heating cycles (briefly
switches on and off) until the set supply temperature
has been reached [set DHW temperature +9°F (+5 K)].
Then it runs constantly. If, during heating, the actual
value falls below the required set temperature, the
circulation pump for tank heating will temporarily cycle
again.
The DHW tank is hot:
H (Tank temperature sensor 1:
Actual value ≥ set value
and
Tank temperature sensor 2:
Actual value > set value -3°F (-1.5 K):
H The common set supply temperature is returned to the
set weather-compensated value.
H The DHW pump stops immediately when the 3-way
mixing valve is fully opened.
or
H The DHW pump stops after expiry of the delay off time
that is selected at coding "62".