On Thu, 28 Feb 2013 20:21:32 +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.

So? Evidence for an air source heat pump having a good COP with air temps
just above 0C. And that you gte more out from the heat pump than you put in
ove the cradle to grave measure?

Do you actually have one of these units yourself?

Not particularly relevant, you have one. What is the COP with say an air temp
of 2C and 80% RH?

Part of the house has storeage heating, which I hate. I'd like to replace
that with something a little more controlable and cheaper. I've been looking
at air source heat pumps, but the drop in COP with low air temps is a major
drawback when we spend quite significant periods (weeks) of the winter with
air temps 5C and high humidty, mist/hill fog.

Assuming a COP of 3.5 under ideal conditions droping that to 2.5 means the
input energy to get the same output goes up by 40%, either that or you get
cold...

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