Viessmann Cascade control unit Installation, Operating And Service Instructions page 19

Operating conditions
Party mode
A switching contact at the party key input enables the control unit to be
changed over to standard mode. The control unit will operate in standard
mode as long as the switching contact is closed.
Set value (multi-boiler control unit)
Party key
time
The control unit can be changed to standard mode for an adjustable period by
connecting a pushbutton to the party key input. After the set period has
expired, the control unit will automatically change back to its previous setting.
In the "Operating details" menu (see page 15), you can scan whether the
control unit is set to party mode.
(cont.)
The impulse at the party key input lets the
control unit operate in standard mode for the set
0h
period.
Please note:
The course of the set standard mode cannot be
terminated prematurely.
Functions
19