On Friday, 5 July 2019 15:11:05 UTC+1, Maurice wrote:
We have a hot-water cylinder with 2 immersion heaters.
Is there such a mains unit that would provide for 2 inputs, and offer a 3-
way choice of:

As well as the manual bath/shower switch MK K5207WHI mentioned by Tuffnell Park below, economy 7 controllers like

https://www.electricaldirect.co.uk/p...control-556045

will do the bottom heater on timed (which can be adjusted using tappets behind the clockface) and the top heater on boost, but not simultaneously.

Owain