Technical data

132
Function description – Vitocontrol-S, VD2/CT3/CM2
Heating circuit control (continued)
Supply temperature control
Differential temperature:
The differential temperature may be
adjusted via coding address 9F; factory
supplied setting 8˚C / 15˚F .
The differential temperature is that
minimum temperature differential by
which the common supply temperature
should be higher than the currently
required supply temperature of the
mixing valve circuit.
System with only one mixing valve
circuit:
The common set supply temperature
will be automatically held 8˚C /
15˚F above the set supply
temperature of the mixing valve
circuits.
System with high temperature
(boiler) circuits and mixing valve
circuits:
The common set supply temperature
operates in accordance with its own
heating curve. The differential
temperature of 8˚C / 15˚F towards
the set supply temperature of the
mixing valve circuits is set up at the
factory.
A Max. common supply temperature
B Slope = 1.8 high temperature
(boiler) circuit
C Slope = 1.2 mixing valve circuit
D Common supply temperature (at a
differential temperature = 8˚C/
15˚F )
E Minimum common supply
temperature
Upper control limit
Electronic maximum limit:
Setting range: 1 to 127˚C /
34 to 261˚F.
Changes via coding address C6.
Please note:
The maximum limit is no replacement
for the underfloor heating system
temperature limiter.
Lower control range limit
Electronic minimum limit:
Setting range: 1 to 127˚C /
34 to 261˚F.
Changes via coding address C5 (only
effective in standard mode).
Control sequence
Mixing valve circuit
The mixing valve motor will not be
activated within the neutral zone
(±1˚C / 2˚F).
Supply temperature falls
(set value –1˚C / -2˚F)
The mixing valve motor receives the
open signal.
The signal duration lengthens with an
increasing control differential. The
duration of pauses reduces with an
increasing control differential.
Supply temperature rises
(set value +1˚C / 2˚F)
The mixing valve motor receives the
close signal.
The signal duration lengthens with an
increasing control differential. The
duration of pauses reduces with an
increasing control differential.
5351 340 v1.4
110
87
+8K
+20/ 68 -20/-4
8K
Supply temperature °C / °F
Outdoor temperature in °C / °F
189
230