Heating The Buffer Cylinder With Booster Heaters - Viessmann VITOTRONIC 200 Service Instructions Manual

Function description
Buffer cylinder
(cont.)

Heating the buffer cylinder with booster heaters

Only the instantaneous heating water heater can be
used as a booster heater for the buffer cylinder, as it is
integrated hydraulically into the flow of the secondary
circuit.
The external heat generator is integrated into the sys-
tem flow via a mixer, downstream of the buffer cylinder.
This results in a direct heating of the heating circuits.
The buffer cylinder is heated by the external heat gen-
erator indirectly via the heating circuit return.
Stop optimisation
The stop optimisation ("Stop optimisation heating
buffer cylinder 7205" set to "1") ensures that the set
buffer cylinder temperature is always reached at the
end of a time phase with the operating status "Stand-
ard".
Cooling of the heating water/coolant buffer cylinder
Note
Does not apply to central cooling if a heating water
buffer cylinder for central cooling is bypassed by
means of a hydraulic bypass circuit.
Switching cooling on and off
If the buffer temperature exceeds the current set buffer
temperature by more than "Start hysteresis coolant
buffer cylinder 722B", cooling of the buffer cylinder is
activated. The current set buffer temperature is always
the lowest set flow temperature of all connected cool-
ing circuits. The set buffer temperature is limited to
"Min. temperature coolant buffer cylinder 722A"
even if a lower value is calculated for one of the con-
nected cooling circuits.
46
For heating the buffer cylinder with an instantaneous
heating water heater: See page 40.
Therefore, the heating of the buffer cylinder starts ear-
lier by the required heat-up time, even if the start con-
ditions have not yet been met. The heat-up time is
automatically set to between 0.5 and 2 h, subject to
the heat-up times of the previous few days.
/
Cooling of the heating water/coolant buffer cylinder
ends if the temperature at the stop temperature sen-
sors drops below the stop temperature or as soon as
"Min. temperature coolant buffer cylinder 722A" is
reached.
Note
In the event of a fault in the buffer temperature sensor,
cooling of the heating water/coolant buffer cylinder is
stopped immediately.