In message ,
writes
On Thursday, 19 April 2018 21:19:41 UTC+1, Tim Lamb wrote:
Well the boiler got installed and eventually the electrician returned to
wire up the system.
Without much thought or any advice, I had opted for W plan. The circuit
diagram looked simple enough:-(

Well it is only 6 connections and earth. Even a plumber should be able
to join that up.

http://wiki.diyfaq.org.uk/index.php?...Controls_and_Z
oning#DHW_priority:_W-Plan

Indeed.

Sadly underfloor systems tend to have individual roomstats and further
complicated by splitting the manifolds upstairs/downstairs.

Boiler overrun provision also needs checking. I don't know if this is
internal to the Viessmann boiler in which case the boiler pump could
circulate through the output/return loop (about 20m of 28mm insulated
piping)

I'll have a play this morning and report back:-)

--
Tim Lamb