I think it was 3 summers ago I fitted a split aircon unit in my
living room. It's 12,000 BTU (3.5kW cooling and a bit more
heating, 3.8kW IIRC). This was after fitting a similar unit
for my parents, and being very impressed with it.

I've had a power meter on it all this year. Started using it in
the early spring to heat the room when I didn't need to heat the
whole house. Through the summer, it did some cooling, although
not as much as in previous years as it wasn't very hot. Used it
again for heating this week. Just checked the power meter, and
it's clocked up 60kWhrs, which comes to about £6.50, which is
much lower than I would have guessed had I not measured it.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]