Hang on, there's something odd here. Immersion heater with 13A fuse OK, (but not via a plug & socket) then what about heating controls and pump. They should be fused at 3A and as I read the thread it appears that they are all connected via the same 13A plug. Yet no one has commented on this, or the total combined load. This sounds dodgy as it is, never mind adding anything else to the 'hash up'. Or have I missed something?With a socket for the Immersion/pump/heating controls.