Viega Multiplex Trio E Instructions For Use Manual page 21

Handling
Seal the hoses for the water connection (2 x R ½ x DN 12).
Screw the hoses to the hot and cold water inputs.
Mount the corner valves to the hot and cold water installations.
Unscrew the filter in anti-clockwise direction.
Remove the filter.
Open the water inlet for a few seconds to flush the pipe.
Multiplex Trio E fitting, electronic mixing unit 21 from 38