On Tue, 11 Dec 2007 02:42:23 -0800 (PST), Pete C
wrote:

Yes, you asked "It would be really useful to find out how he achieved
the fivefold
increase in performance"

and I answered, or at least pointed you to the answer.

The problem is the inconsistency of that answer. It simply isn't
possible for the solar panel to contribute the amount of heat saved.
However, nor is it likely that the control changes could amount for
the unexplained 80% of the saving which cannot be attributed to the
solar panel.

If the control changes alone _did_ make this difference then that
makes them a much more worthwhile investment than would normally be
thought to be the case. The alternative is there is ome of factor or
factors which have led to the saving or its calculation and we don't
know what they are.