"daestrom" wrote in message
...

"Ron Purvis" wrote in message
...

wrote in message
oups.com...
Derek Broughton wrote:

The "figures" are a ridiculously low number for cost of hot water that
you
made up. I can _easily_ save £100 a year with a system that will cost
me
about that much. Check back next year for real use figures...

Good lord. None of the figures are cost of hot water.

The £20 a year figure is proposed saving from a basic system, and will
vary a fair bit IRL.

The £100 a year figure is how much a £2000 system would need to save
per annum to ever pay its way even if you made the most wildly
optimistic assumptions.

What you don't seem to understand is that just because you made up a
number, doesn't make it valid. Your number has no basis in reality.

His '100' number is 5% annual return on a '2000' investment (or, the
interest on a 2000 loan). While one may quibble about the exact interest
rate, 5% isn't all that far off from current reality.

As far as how much one saves, that is open to debate. After all, how much
a household uses can vary quite a bit with the particular residents. And
system performance as well.

daestrom

My quibble was with the made up number of only saving 20 British pounds a
year. I was not referring to the 5% annual return.