Viessmann Vitoligno 300-P Service Instructions For Contractors page 114

Function description
Control functions
External connections at plug aVD
1 2 3
143
A External demand/Heating program
changeover/External "Mixer open"
(zero volt contact)
B External blocking/external "Mixer
close" (zero volt contact)
Preselected heating pro-
gram
(Contact open)
Central heating
9
OFF/DHW OFF
or
Central heating
w
OFF/DHW ON
or
Central heating
rw
ON/DHW ON
114
(cont.)
A
B
Code
D5:0
(delivered
condition)
D5:1
External heating program change-
over/external "Mixer open"
The "Mixer open" function can be allo-
cated via coding address "9A" (see
page 63) and the heating program
changeover (see page 62) can be allo-
cated to heating circuits via coding
address "91".
Changed heating program
(Contact closed)
⇔
Constant operation with
reduced room temperature/
DHW OFF
⇔
Constant operation with stand-
ard room temperature, DHW in
accordance with coding
address "64"