Combi or system boiler for new build with UFH?

[bernardgreen]

but by the time it comes up from the tank into the roof space along and drops down the wall it will be around 12m.

For what it is worth....

My cottage has a similar problem of long pipe runs ( > 10 metres ) between kitchen and bathroom.

My solution to avoid the inconvenience and waste of waiting for hot water to reach taps furthest from the hot water cylinder was to have two hot water cylinders. One small cylinder in the kitchen and a larger one in the bathroom.

 

[oldbutnotdead]

Another thread has started up about when TMVs are needed:
https://www.diynot.com/diy/threads/requirement-for-thermostatic-mixing-valves-tmvs.551603/

Useful that, ta. Bath only in domestic situations apparently (which is not the story you get from manufacturers guidance sheets. Lesson noted )