In an earlier contribution to this discussion,
Stephen wrote:

On Fri, 5 Sep 2008 22:06:42 +0100, "Roger Mills"
wrote:

Yes, or even less. Very few systems with conventional boilers run at
a dT of 60 - 55 is more usual.

Sorry to start this up again but I have been using the Barlo heat loss
program and see it has an option to set water temperature. Does it
matter what this is set to? I presume that it makes no difference to
the room heat loss calculation but is only used if you ask it to
select appropriate radiators from the Barlo range?

Yes, that's right.

I have tried the Myson program and it gives slighly lower heat losses.
Any idea which program is nearest the mark?

Not really, but if you want to be safe, take the higher heatloss figure.
Have a close look at what U values each program uses for various types of
construction. Differences in U value will give differences in heat loss.
Also look at air changes per hour; that makes a difference, too.

I'm not quite sure what materials to list my walls as. Am I right to
think that the downstairs ceiling/upstairs floor should be selected as
floorboard/joist/plaster where I have a joist with a floorboard on one
side and plasterboard the other?

That sounds about right. Unless there is a large temperature difference
between upstairs and downstairs (like heating one but not the other at
certain times) the heat loss/gain through the ceiling and upstairs floor
won't be much anyway - particularly if there are carpets upstairs.

I know three walls of the house are cavity with a brick outside and
breeze block inside so I guess that's the brick/breeze cavity option?

Yes. Are the cavities insulated? If so, there should be an option for that,
too.

The problem is that the front of the house is tile clad on the
outside, with who knows what behind it, I guess a single breeze block?
What would this be described as?

The programs may not have an exact match for this - but selecting a
brick/block or block/block cavity wall probably won't be far out. I think at
least one of the programs allows you specify your own wall type - complete
with U value - in which case you can insert an appropriate value. I have a
feeling that there is information about typical U values on one of the
government sites - where building regs etc. can be found - but don't ask me
exactly where - the appropriate government department (the one which used to
be Prescott's) seems to re-invent itself too often for me to be to be able
to keep up with it!
--
Cheers,
Roger
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