On 02/10/2020 10:39, Dave Liquorice wrote:
On Fri, 2 Oct 2020 10:13:17 +0100, The Natural Philosopher wrote:

in merely cool weather a heat pump can achieve a 4:1 uplift which puts
it at about 5p/KWh.

That's comparable in my case with oil at 50p/liter.

Not bought oil or looked at prices recently? Around 30p/litre these
days. (32.37 + VAT on 18th March...) Pre Covid 'twas around 50p/l.

And remember in the depths of winter even a 5KW heat pump at 2:1 uplift
may not be enough...

10 kW certainly wouldn't be enough here. Retrofitting a heatpump
system to and old property and greatly upping radiator sizes to get
enough output from them at 40 to 50 C strikes me as fraught with
problems. It certainly won't respond quickly to a cold snap.
Underfloor at least stands a chnace with a big thermal mass and
surface area to store and release heat at hopefully a decent rate.

Really heat pumps need massive insulation to reduce heat loss and
ginormous radiators or UFH or in wall pipework. That is almost
impossible to retrofit to an older house at a sane cost


--
"When a true genius appears in the world, you may know him by this sign,
that the dunces are all in confederacy against him."

Jonathan Swift.