On Wed, 27 Feb 2013 09:01:49 +0000, Malcolm wrote:

With which bit? Crap performance of air source heat pumps with air
temps just above 0C or contesting "Output input every time" on a
cradle to grave basis?

Both. We've had low temperatures the last few days and nights and are
living in a warm house, with the air source pump only on during the
day.

Have you measured how much heat it has produced and how much energy it has
consumed? With air temps just above freezing the collector ices up, ice is a
good insulator, the unit has to regularly defrost the collector. This is what
gives them crap performance under such conditions. It'll still churn out the
heat but with a poor COP.

Any evidence of cradle to grave energy costs?

--
Cheers Dave.
Nr Garrigill, Cumbria. 421m ASL.