Overheat protection STB heater

Overheat protection, STB, for heater.

Suitable
Vaillant VWL 9C
VWL 71/2
VWL 91/2
VWS 61/2
VWS 62/2
VWS 63/2
VWS 64/2
VWS 81/2
VWS 82/2
VWS 83/2
VWS 84/2
VWS 101/2
VWS 102/2
VWS 103/2
VWS 104/2
VWS 141/2
VWS 171/2
VWW 61/2
VWW 62/2
VWW 81/2
VWW 82/2
VWW 101/2
VWW 141/2
VWW 171/2
VWL 61/3 S
VWL 62/3 S
VWL 81/3 S
VWL 82/3 S
VWL 101/13 S
VWL 102/3 S
VWL 141/3 S
VWL 171/ 3 S