Retro fit ASHP with 2nd zone and UFH

[AberDoc]

I have a Valliant ASHP with a hydraulic station running DHW and a radiator circuit. This is all controlled via a VRC700 unit operating on eBus.

I am looking to replace 5 traditional radiators with UFH, but Valliant do not offer advice on this as they don't sell UFH components.

A 1980s extension with basically zero insulation has been expanded from 12 m2 to 24 m2 and is about to be fully insulated.

I need to make a decision on the floor celotex then concrete for traditional floor or concrete then celotex plus screed for UFH

Looking at this logically my belief is this is possible via the following:

Add VR70 2 zone wiring box

Add VR91 secondary wired thermostat on eBus for UFH zone 

add UFH flow temp stat

add 2 x zone valves (1 for rads and one for UFH)

add UFH manifold with non blending pump (circulating water is 40C) 3 way non attenuated 10mm outflow pipes 

Is this sensible or should I just reinstate the rads?

Edited March 16, 2023 by AberDoc
spellings

[ReedRichards]

Do you want the underfloor heating for aesthetics/space-saving (no radiators) or comfort or economy of operation?

[AberDoc]

space saving primarily 

[ReedRichards]

I asked because you may or may not get any improved economy from a mix of UFH and radiators, as was discussed today on another thread.

[AberDoc]

thanks, I am hoping that the new build will increase the overall efficiency of heat retention within the property.