Andy Hall wrote:

However, in a new property it is possible to easily provision an
adequate mains water supply. This may not be so easy in an older
property, so before rushing off to chase imaginary regulations, do
check the mains water supply to make sure that it is adequate.

The only way to meet the backup requirement is through some form of
storage - none of the mains fed hot water systems inherently do that.

In terms of mains fed hot water systems, apart from combi boilers you
can have a pressurised hot water cylinder - stores the hot water and
is heated via a coil similar to an open vented system - or a thermal
store where the bulk water is heated directly or indirectly by the
boiler and that is pumped through an efficient heat exchanger when
required. Both of these get you over the rate of heating problem of
low to mid range combi boilers in that they store the hot water or the
energy to heat it.

However, they are only as good as the mains supply.

Having said that, there are on the market, pressurised water storage
vessels. IIRC, these operate on a similar principle to the pressure
vessels used in sealed CH systems- i.e. with a diaphragm with air or
nitrogen on one side, water on the other. The application is for
where the static pressure of the supply is OK but the flow rate poor,
and there is a requirement for periodically large amounts of water.
I believe that these can be fitted on a ground floor - I tried to find
the manufacturer, but can't for the moment. ISTR them being quite
expensive, however.

This has been suggested to me:
http://www.gah.co.uk/GAH_Dualstream/frameset.htm

No idea about cost though. I also note that the diaphragm only
has a 2-year warranty.

Alternatively, you could have a break tank in the garage, mounted
above a single feed pump.

Chris
--
Chris J Dixon Nottingham UK


Have dancing shoes, will ceilidh.