Dhw Tank Temperature Control - Viessmann Vitotronic 300 GW6B Installation Instructions Manual

Vitotronic 300, GW6B Installation and Service

DHW Tank Temperature Control

Brief description
H The tank temperature control is a constant temperature
control function. This is achieved by starting and
stopping the DHW pump. The switching differential is
±2.5 K.
H When the DHW tank is heated, a set supply
temperature is specified that is 20 K higher than
the set DHW temperature (adjustable at coding
"60" in the "DHW" group).
Functions
Time program
An automatic or an individual time program may be
selected for DHW pump and the DHW recirculation pump.
Compared with the heating circuit heatup phase, DHW
heating starts 30 min earlier in automatic mode.
The individual time program enables up to 4 time
phases per day to be set for DHW pump and the DHW
recirculation pump for every day of the week.
All tank heating sequences will be completed
independently of the time program.
In conjunction with coding "7f" in the "General" group
H Detached house
Coding "7f:1":
– Automatic mode
The heating times for heating circuit 1 are applied
to systems with two or three heating circuits.
– Individual time program
The time phases for DHW pump and the DHW
recirculation pump have the same effect on all
heating circuits.
H Apartment building
Coding "7f:0":
– Automatic mode
For systems with two or three heating circuits,
the heating times for the respective heating circuit
will be applied.
– Individual time program
The time phases for DHW pump and the DHW
recirculation pump can be adjusted individually for
each heating circuit.
Priority control
H With priority control: (coding
"a2:2" in the "Heating circuit..." group):
The set supply temperature will be adjusted to 32°F
(0°C) during tank heating. The mixing valve closes
and the heating circuit pump is switched off.
H Without priority control:
The heating circuit control unit continues to operate
with the same set value.
H With modulating priority control in conjunction with
heating circuits with mixing valve:
The heating circuit pump remains switched on.
During tank heating the set supply temperature of the
heating circuit will be reduced until the set boiler water
temperature has been reached.
The set supply temperature is determined from the
following coding:
– Outdoor temperature
– Differential between the set and the actual boiler
water temperature
– Heating curve slope and shift
– Set coding "a2" in the "Heating circuit..." group
Frost protection
The DHW tank will be heated to 68°F (20°C) if the DHW
temperature falls below 41°F (5°C).
Forth phase heating function
(auxiliary function for DHW heating)
This function is activated by providing a second set DHW
temperature at coding "58" in the "DHW" group and
activating the fourth DHW phase for DHW heating.
Set DHW temperature
The set DHW temperature can be adjusted between 50
and 140°F (10 and 60°C).
Coding "56" in the "DHW" group enables the set range
to be extended to 203°F (95°C).
Coding "66" in the "DHW" group enables the set value of
the programming unit and/or remote control Vitotrol 300
to be assigned.
DHW recirculation pump
This delivers hot water to the draw-off points at
adjustable times. Four time phases can be selected
at the control unit for every day.
Function Description
81