"Dave" wrote in message
...
Do you happen to know whether the U values in the myson software are
correct?
Estimating air exchange is tough, any suggestions on how to approach it?

I use Myson V1.05, not sure if that is the latest version or not. Noticed
recently that there is a design program available at
http://www.centralheating.co.uk for £15.

Find the Myson useful for the maths because it takes into account your mean
water temperature and the room temperature but then transfer the results to
a spreadsheet. There is a "funny" with this version. The required outputs
are presented on a Dt60 basis but with a confusing product reference comment
to Dt50 and so have to be factored down to Dt50 before they are useable with
current rad data.

Jim A