On Mon, 4 Mar 2013 17:40:21 +0000, Malcolm wrote:

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?

Please tell me how I would measure that - simply and without too much
effort on my part.

Air to water I'd expect to have some heat metering built in. Though if it's
anything like the heat metering built into our solar thermal controller it
would be next to useless(*). Otherwise it's probably not possible. The makers
information ought to have it but I wouldn't be surprised if the COP at
various outside/inside air temperatures was quietly side stepped.

I've no idea and am not that interested. The bills from the fuel
suppliers are, to my mind, more relevant.

Part of the house has storage heating, which I hate.

And rightly so. I was involved just over a year ago in replacing six
night storage heaters in a small local museum with a 10kW air-to-air
heat source pump.

As you are so keen on getting the bills down how come they installed air to
air? That was excluded from the RHPP (£850 grant payment for air to water)
and the RHI. The RHI could be paying them 4.7p/unit produced now (Under the
"commercial" Phase 1 part of the RHI) for the next 20 years.

Well, if you're right about COP, then that's important to you. But you
should ask yourself whether you should be worried about it

Electricity is not going to go down in price over the next 5 to 10 years.. If
a dozen or so nuke stations get built it might at least stabilise.

(*) Takes the panel manifold temperature and the tank bottom temperature and
the transfer fluid flow rate. That temperature difference is normally *far*
higher than the temperature difference between the flow and return of the
transfer fluid loop. It is the latter that really shows how much heat has
been transferred from the fluid to the tank.

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