Function Description Constant Temperature Control Unit - Viessmann VITODENS 222-F Installation And Service Instructions Manual

Function description
Constant temperature control unit
s
Heating mode
The selected set boiler water tempera-
ture will be maintained when a demand
is being raised by the room thermostat
and the heating program is set to DHW
and central heating "G".
The boiler water temperature will be
maintained at the default frost protection
temperature when there is no demand.
Heating the DHW primary cylinder from cold
The heating circuit pump is switched ON
and the three-way diverter valve will be
changed over, if the cylinder tempera-
ture sensor captures a temperature
lower than the defaulted set tempera-
ture.
■ The cylinder primary pump is switched
ON if the boiler water temperature ≥
set DHW temperature.
■ The burner is switched ON if the boiler
water temperature ≤ set DHW temper-
ature, and the cylinder primary pump
is switched ON when the required
boiler water temperature is reached.
126
°C
4 8
A
The electronic temperature limiter inside
the burner control unit limits the boiler
water temperature.
Flow temperature setting range: 20 to
74 °C.
The primary cylinder is heated up to the
set DHW temperature. Heating stops
when the set temperatures have been
reached at the cylinder temperature sen-
sor and at the outlet temperature sen-
sor.
After heating, the cylinder primary pump
and the three-way diverter valve remain
ON for a further 30 s.