On Sat, 20 May 2006 02:44:58 -0700, wrote:

... we are planning on putting the new boiler and DHW tank in
the loft.

Following research on google we have decided that an indirect Pandora
heatbank best fits our DHW needs
....
The Pandora I have initially specified is 180l / 100kw / inlcuding two
2 port valves (S plan) that would serve heating/DHW.

That's going to be fun to get into your loft!
(and to site safely)

Now the main issue - choosing an appropriate boiler to cater for the
heatbank and also serve the heating (radiator) system. Following
various discussions with my plumber we have calculated our heating
requirements at around 26kw and to err on the side of caution we are
looking at boilers between 28-31kw.

That's an awful lot of heat. How many rooms does your mansion have, to the
nearest dozen? :-)

Have you checked with the whole-house calculations on

http://www.est.org.uk/housingbuildin.../boilersizing/

and

http://www.idhe.org.uk/calculator.html

(Note that the latter is wrong for mid-floor flats, at least.)

I'd expect to size a boiler at around 10-15kW for normal sized houses.
OTOH if you can afford a Pandora and a MAN then maybe you also have a
house with that sort of heating requirement :-)