Viessmann Vitocrossal 300 CA3 2.5 Installation And Service Instructions Manual page 133

Vitocrossal 300 CA3 Series 2.5 to 6.0 Installation/Service
DHW Tank Temperature Control
Auxiliary circuits
DHW heating in conjunction with the heating circuits can
be disabled or enabled by changing over the operating
program (see coding "d5" in the "Heating circuit..." group).
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.
The DHW tank is only reheated by the boiler if the
temperature falls below this value.
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.
Controlled sequence single boiler control
Coding "55:0" in the "DHW" group; tank heating
The DHW tank goes cold [set value -5°F (–2.5 K),
adjustable via coding "59"]:
H The set boiler water temperature is set 36°F (20 K)
higher than the set DHW temperature (adjustable via
coding "60").
H Pump on:
– Starting the DHW pump is subject to boiler water
temperature (coding "61:0").
The DHW pump starts when the boiler water
temperature is 14°F (7 K) higher than the DHW
temperature.
– Starting the DHW pump for tank heating
immediately (coding "61:1").
The DHW tank is hot [set value +5°F (+2.5 K)]:
H The set boiler water temperature is reset to the
weather-compensated set value.
H Pump delay off:
The DHW pump runs on after tank heating
until one of the following criteria is met:
– The differential between the boiler water temperature
and the DHW temperature is less than 13°F (7 K).
– The weather-compensated set boiler water
temperature has been reached.
– The set DHW temperature is exceeded by 10°F (5 K).
– The set max. delay off time is reached (coding "62").
H Without pump delay off (coding "62:0").
(continued)
Adaptive tank heating
Coding "55:1" in the "DHW" group;
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),
adjustable via coding "59"]:
H The set boiler water temperature is set 36°F (20 K)
higher than the set DHW temperature (adjustable via
coding "60").
H Pump on:
– Starting the DHW pump is subject to boiler water
temperature (coding "61:0"):
The DHW pump starts when the boiler water
temperature is 13°F (7 K) higher than the DHW
temperature.
– Starting the DHW pump immediately (coding "61:1").
The DHW tank is hot:
H The control unit checks whether the boiler will still
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 DHW pump stop times to prevent the set
DHW temperature being substantially exceeded after
the tank has been heated up.
Function Description
133