Viessmann Vitoligno 250-S Installation And Service Instructions For Contractors page 43

Additional heat generator group
Coding in the delivered condition
Parallel operation
D7:1 Parallel operation of both heat
generators is possible.
Note
Parallel operation only possible if
the additional heat generator has a
boiler circuit pump.
(cont.)
Possible change
D7:0 Parallel operation of both heat gen-
erators is not possible.
Code 1
43