How to adjust and install a Vaillant VRT-QZA brand thermostat?

Adjustments and installation of a Vaillant brand thermostat, the VRT-QZA.
A little obsolete because it hasn't been in the catalog for 20 years, but you never know.
Notice here: pdf.lu/F7Tz
My essentials:
Hex key (allen or BTR): amzn.to/3tWXHmG
Hose for draining the boiler: amzn.to/3tXTBdS
Grease I use: amzn.to/36GQvCp
My joint paste sealing kit, Amazon affiliate link: amzn.to/3x08PAP
My Digital Multimeter: amzn.to/3wXlp3S
Pump that I use for inflating expansion tanks: amzn.to/3XAE5RR
Amazon affiliate links.
Video No. 282

[@69PlombierChauffagisteRamoneur]

Salut bon Dimanche soir :) /alex

[@conceptchauffage]

Salut bonne semaine