Bosch W11P - Manual (Page 8)

Turn on all gas and water taps
Purge air from pipes
Output Control:
Fig. 5
4. Operation
Depress slide control knob
and hold it in
Ignition:
output decrease output increase
Press the piezo igniter
Repeat these steps if the flame does not stay alight
Switching off:
Release the slide control knob
after approximately 15 seconds
Move slide control to the far left
Turning control anti-clockwise
increases water flow rate and
reduces water temperature
Turning control clockwise
reduces water flow rate and
increases water temperature
Temperature adjustment