Technical data

129
Function description – Vitocontrol-S, VD2/CT3/CM2
Cascade control (continued)
Net calorific strategy 2 (coding 3C: 2)
Start-up Switching OFF
Boiler sequence
The boiler sequence is determined by
the boiler sequence selection and the
following coding addresses (see also
page 168):
38 Changing the lead boiler and the
boiler sequence.
38: 1 Every 1
st
day of the
month, the boiler with the
burner which has
operated for the shortest
number of hours becomes
lead boiler.
38: 2 After 200 to 20,000 run
hours, the boiler with the
next higher number
(coding address 07 of
Vitotronic 100) becomes
lead boiler.
39 Boiler 1, 2, 3 or 4 permanent lead
boiler.
3A Boiler 1, 2, 3 or 4 permanent last
boiler.
41 ECO threshold boiler 1.
42 ECO threshold boiler 2.
43 ECO threshold boiler 3.
44 ECO threshold boiler 4.
Via the ECO threshold, every boiler can
be disabled or enabled subject to the
outdoor temperature. The ECO control
becomes disabled, if the boiler is
required to achieve the set supply
temperature, when enabled boilers
have failed. At least the lead boiler
remains active if all boilers in a system
are disabled by the ECO control.
5351 340 v1.4
Time
0
0
0
33
50
33
100
100
100
150
200
Total Boiler 2 Boiler 1
Rated output in kW
50
Time
0
0
0
33
33
33
66
100
100
100
150
200
Total Boiler 2 Boiler 1
Rated output in kW