[OT] Thermal Stores for hot water/heating

["Jonathan Shaw" <semi.jon@xxxxxxxxxxxxx>]

I read a lot about hot water cylinders before talking to plumbers and
decided that with underfloor heating + radiators & a condensing
boiler that a thermal store was the best option as theory is that
even when heating the house (rather than water) the themal mass of
the heatstore gives the boiler something to work on and
prevents/reduces boiler cycling/ inefficiency associated with
condensing boilers and zoned heating whre only one room may be
calling for heat.

None of the (getting on for 10) plumbers I have spoken to think this
is a good idea.  All generally vague reasons that seem to centre
on "I fit what I know" rather than listening to customer; oh and
the
annual service for the pressure relief valves needed for unvented
cylinders, nice litle earner.  One suggested in hardwater areas the
heat exchanger would calcify, but Googling doesn't seem to back this
up.  Naturally eh suppliers (Chelmerheating, Nu-heat, Gledhill) all
deny this is a problem.

Are there any heating engineers on the list that can offer advice?
Or anyone with a thermal store in a hardwater area?

TIA
Jon