The point I'm trying to make is where can I go to get a good,
impartial recommendation about the right kind of system, and what
specification that system should be? It's no good talking to a plumber
because all you will get (in my experience) will be "You want a combi,
gov! Sort you out a treat it will!" before they even know how many
bathrooms I have, or whether I have a washing machine and a
dishwasher, or how many people live there.

I have not read previous posts on the subject (but I have read the faq). So here
are my thoughts:

The size of a boiler needs to be matched to the size of the radiators etc to
which it will be attached.

The heat loss from each radiator depends on its area. If you cant find this in
a radiator catalogue or else where try a factor of 170 Btu/sq ft /hour


You can also work out the heat loss from the pipe work. Say 10 Btu/hour per foot
lenght for 15mm piping.

Do you have an indirect cylinder and will you be keeping it? A ball park figure
for an indirect cylinder is 12000 Btu/hour

Calculate the total heat loss and then maybe add on a safety marging say 20% and
this will give you an idea of what size boiler to use. The look to see what
size boilers you can buy and what the difference in price between a small one
and a larger one is. This will give you and idea of what to do. Also how big is
the boiler that you have now? does it run continously on a very cold day or does
it spend time switched off whilst the radiators cool the water/boiler to the
point where the boiler will start gain.


Alternatively get a few quotes and look what size of boiler is specified.

You might also want to consider a high efficiency condensing boiler. Do you
want to dispense with your expanion tank and hot water tank )which I assume that
you have now)

Happy Xmas
Michael Chare