On Tue, 1 Dec 2020 10:30:18 +0000, Andy Bennet wrote:

Water Heater Top 3.0kW Water Temp 50C
Water Heater Bottom 3.0kW Only for Boost

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

Yep amd 50 C isn't really hot enough, doesn't relaibly kill
legionella.

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Cheers
Dave.