On Sun, 8 Jan 2006 at 23:45:29, Ed Sirett
wrote:
On Sun, 08 Jan 2006 10:55:03 +0000, Rick Bowlby wrote:

On Sat, 7 Jan 2006 at 20:17:12, Ed Sirett
wrote:
On Sat, 07 Jan 2006 12:14:49 +0000, Rick Bowlby wrote:

1) With condensing boilers is it still important to get the 'right' size
or might there be benefit in over-sizing a little?

1) Yes, see BoilerChoice FAQ (this is quite new so you may have missed it).

Which is 'yes'?! Actually I had read the FAQ, which was helpful -
"Modern boilers can adjust their output power over a range
automatically, therefore over-sizing is less of a sin that it used to
be, nevertheless getting this right will save some gas". However I do
want to ensure that there is a decent HW flow rate. Heatloss manager
reckons I need a 25kW boiler for heating, so I was thinking of going up
to 30-35 to be on the safe side with HW.

Seriously. That's a gross over estimate of the HW requirements when
combined with a cylinder/thermal store. You'd only need that sort of HW
if you have a stack of people (12+) people living at your place.

28-30kW (load of models around that size) would be quite enough.

However you should allow 40 litres of stored HW/person.

But I want to get a combi boiler and mains pressure HW, does that make
any difference?
--
Rick Bowlby