Iíve got an EvoHome Y-Plan system that I installed myself. Iíve done it exactly as per the book, with a BDR91 relay on each side of the 3-port valve. Wiring in the 10-way junction box is as per page 47 of the installation guide. Initially I was thinking that at some point I might add a third relay for boiler control, but the default TPI is working fine for me anyway.
All the radiators have HR92s on them apart from the Bathrooms which have retained their TRVs. The hot water cylinder has the CS92 hot water kit fitted. The boiler is a traditional system boiler, however itís running with an external expansion vessel in the loft rather than a tank. The pump is set to a fixed speed. I do not believe that there is an automatic bypass valve. (And yes, with most of the radiators closed the valves whistle a bit)

Weíre looking at having the Kitchen done. Not just units but some building works too and as part of that having warm water Under Floor Heating fitted to the newly enlarged room rather than the existing HR92 radiator. The Kitchen work will be done by a local indie (not the big chains!) and they will be managing the trades.

I'm not expecting their plumber will know EvoHome, so before speaking to their plumber Iíd like to get my head around it first...

Whatís the best way of adding in UFH into an existing Y-Plan system and then controlling it with EvoHome?

I'd like to do it properly and if that means additional complication in converting to S-Plan 2-port valves with automatic bypass etc then so be it - I'd rather it was done the best way than any cheap bodges.