Viessmann VITOTRONIC 300 GW2 Installation And Service Instructions Manual page 89

Heating circuit control
Functions (continued)
Upper limit of control range
Electronic maximum limit
Setting range:
1 to 127°C / 34 to 260°F.
Change via coding address "C6".
Please note:
The maximum limit does not replace
the limit thermostat required for
underfloor heating systems.
Limit thermostat for underfloor heating
systems:
The limit thermostat switches the
heating circuit pump off when the
supply temperature rises above the
preset value. In this situation, the
supply temperature cools down only
slowly, i.e. automatic re-starting can
take several hours.
Control sequence
Mixing valve circuit
The mixing valve motor is not activated
within the "neutral zone"
(±1°C / 2°F).
Supply temperature falls
(Set-point value –1°C / -2°F)
The mixing valve motor receives the
signal "Open mixing valve".
The greater the control difference, the
longer the duration of the signal and
the shorter the duration of the
intervals.
(continued)
Lower limit of control range
Electronic minimum limit
Setting range:
1 to 127°C / 34 to 261°F.
Change via coding address "C5".
Supply temperature rises
(Set-point value +1°C / +2°F):
The mixing valve motor receives the
signal "Close mixing valve".
The greater the control difference, the
longer the duration of the signal and
the shorter the duration of the
intervals.
Functional description
89