Electric Boiler - confused

Qyburn

markin said:

The is no 3-way valve but im not certain the boiler is not heating the tank, they seem connected.

I see a two-port valve, silver housing with yellow warning sticker, just above the paint tin in tge second photo.

Is there another similar one anywhere?

Qyburn

Five separate switches, as well as the programmer! Enough to confuse anyone. It's going to be a job working out what each switch controls, and where it's fed from.

For example the right hand immersion switch, controlling the lower immersion, looks like it may have a separate supply.  Could be off peak? That would make some sense with off peak heating the whole tank, and separate boost immersion mounted higher to provide top up when needed.