On Tue, 1 Dec 2020 12:35:55 -0000 (UTC), jon wrote:

I would swop over your top and bottom heaters, you only want to
heat
the top for boost.

Manual boost is not used during the night, so is not counted in used
kWhs.

But if the boost heater is at the bottom you heat the whole tank when
you use boost, not just the top.

--
Cheers
Dave.