TheScullster wrote:

Do you have a link to this requirement please John?

http://www.odpm.gov.uk/stellent/grou...reg_600288.pdf

I have seen people advise the use of fast recovery cylinders, but never
stipulated as a requirement for Building Regs!

Yup sorry, I might have overstated the requirements slightly, reading
the detail :

"1.43 For systems incorporating integral or
separate hot water storage vessels, ways of
meeting the requirement include:
a) arranging for hot water storage systems to
meet the insulation requirements of BS 1566,
BS 699, BS 3198, or BS 7206 (as appropriate);
or
b) in ordinary cases, insulating vessels with a
35mm thick, factory-applied coating of
PU-foam having a minimum density of 30kg/m3.
(For unvented hot water systems additional
insulation should be provided to control the
heat losses through the safety fittings and
pipework but without impeding safe operation
and visibility of warning discharges. (See
Approved Document G.)"

And:

"1.44 Provisions should enable efficient
operation without excessive boiler firing and
primary circuit losses. A way of demonstrating
compliance for indirectly heated hot water
storage systems would be for the size of the
heat exchanger to be at least that
recommended in BS 1566, BS 3198, or
BS 7206 (as appropriate) and for them to be
served by a pumped primary system."

I have not looked at BS1566, or 3198, but it looks like there is a
rquirement to meet L1, but that does not need to be as fast as a "fast
recovery" cylinder. Just well insulated and fast ish!

--
Cheers,

John.

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