Many apologies. I forgot to add the line that said I had got a figure of 46Kw when I used the whole house sizing method. Sorry, it all looked way out.
That is why I found the Stars number a bit low and have checked that I used the same u-values for the same elements of the model.
I'm...
I'm lucky(!) enough to be moving into a large old timber framed house which needs quite a lot of updating . The central heating seems to be in fairly good condition and has a Boulter Pathfinder oil boiler (45Kw), TRVs on radiators but a hot water tank about as far away from the boiler as could...