Viessmann VITOCAL 151-A Installation And Service Instructions Manual page 128

Indoor unit maintenance
Removing hydraulic components and EPP...
3.
BK
4.
6.
Fig. 77 Observe the colour coding of the core wires
connected to the high limit safety cut-out (as
per IEC 60757):
BK Black
RD Red
WH White
128
RD
WH
5.
?
7.
7.
(cont.)
2.
!
1.
8.