Salus ST620VBC - Boiler Control Modes; Boiler Control Mode Explanations

RF Boiler Control
When the switch on the Boiler Module is in the AUTO position, the
Boiler Control will automatically receive the RF signal from the
ST620 and control the module output so that it switches the boiler
accordingly.
The user can also move the switch to the MANUAL ON position;
when in this mode, the boiler will be always turned on and the LED
indicator will also be lit constantly.
The user can also move the switch to the OFF position; when in this
mode, the boiler will not receive a signal from the ST620 and the
LED indicator will also be lit constantly.
ST620VBC INSTRUCTION MANUAL20
Salus ST620VBC Manual 008_89 09/02/2012 14:00 Page 20