On 8 Oct 2004 02:45:03 -0700, (Simon Langford)
wrote:

Then I opened up the ground and first floors just a little bit, until
some warmth came through. This morning when the heating came on,
everything was nice and warm.

That's promising.

When I checked the pressure in the system before forcing the heat up
to the top floor, it was at 1 bar. After getting the top floor hot it
was down to almost zero, so maybe there was a blockage somewhere which
has now been shifted.

Checkout Ed Sirrets combi/Sealed System FAQ.

I'm going to do a proper bleed tonight, and
might get myself a digital thermometer as recommended here, to do a
proper balance.

Having tried the digital multi-meter thermocouple type, and the 'pocket'
IR type, I can assure you that the IR type makes the task an order of
magnitude easier. I can't find the one I have online anymore, but these
two look similar
http://www.thermometersdirect.co.uk/item257.htm
http://www.mh-1.com/ordering.htm

I'm still pretty sure that the boiler runs flat out (i.e. never cuts
out under its own thermostat). It is quite a large house, especially
the ground floor which is more than twice the area of the other floors
and has some very high ceilings. So maybe a 24KW boiler is only just
up to the job?

A google search for Andy Hall's posts on calculating what the radiator
(and hence boiler) sizes should get you the info you need to check it
out.

With an undersized boiler, accurate balancing is even more important to
get the best of what you have. If the boiler is undersized, you probably
will end up with a larger temp drop across the rads than the oft quoted
11C; that doesn't matter - what is important is to get the same drop
across each rad.

We're about to remove a large radiator from the
kitchen and put a wood burning stove in its place, so that might help
the boiler load. (I know the kitchen will be colder when the stove's
not lit...)

I have a friend who managed to connect a wood-burning stove (with back
boiler) in parallel with his central heating boiler.

Phil
The uk.d-i-y FAQ is at http://www.diyfaq.org.uk/
Remove NOSPAM from address to email me