Norsup P13X/32 Installations- Und Gebrauchsanweisung Seite 20

4.OPERATION AND USE
(4) Silent setting and silent timing setting
Click the silent setting button ,and the interface displays as follows:
4-1 The silent button
Click the silent button , the unit will enter the silent mode, and
interface displays as follows:
Click the silent button again, to exit the silent mode.
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