My switchmaster SM905 is ticking loudly all the time - Why?

Hot Water System?

Sunvic select 107 XLS + Glow worm ultracom hxi?

i need fixing instructions for the switchmaster sm 905?

switchmaster 805 not turning?

rReplacing a Switchmaster 3 way motorised valve with a Drayton 3 way valve?

Switchmaster sm805 How does it work?

3 way valves?

Switchmaster 905?

replacing switchmaster midi 3 port valve?

The timer is not working on my Switchmaster 905 heating timer?

switchmaster cylinder stat to honeywell cylinder stat?

switchmaster?