In article ,
IMM wrote:
Unfortunately that is the case. It is best to use a diverter and a quick
recovery cylinder that takes all of the boilers heat, rather than a
mid-position valve. The cylinder will re-heat in quick time and make no
effect on the house heating for the short time it is re-heating the
cylinder. Quick recovery cylinders use less gas overall, and can be
downsized as they re-heat so fast.

If you want to wire any system for hot water priority it shouldn't be a
problem. After all, the ability should exist for hot water only in the
summer.

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*The more people I meet, the more I like my dog.

Dave Plowman London SW 12
RIP Acorn