24
The voltage generated by the PCB can vary according to the incoming mains voltage and
therefore it maybe necessary to select a different range on your multimeter. These are DC
voltages which can fluctuate from 19 – 22V DC.
It is important to understand that the PCB generates a voltage that requires switching at
the relative component in order for the lighting up sequence to activate. In the case of the
micro switch 21V DC is supplied from J4 (second wire from right) and assuming water is
flowing through the hydraulic valve, then the signal voltage will be switched and returned
to the PCB at J4 first wire on the right. This principle also applies to the external controls
e.g. the time clock and room thermostat. The contacts in either of these must be closed for
the central heating to operate.
To Next Page
Loading...
