Air-source heat pumps - are they good/crap?

I don't know, but they did claim they were looking into it. How serious/realistic I can't say it's not my field. I suppose there is an arguement but if the CCGT stations can't make money they close down and we still need them. I guess there's some pricing mechanism in the middle.

Well, of course they did. It was politically expedient to make such a pronouncement at that time.

Ive been unable to find any evidence that this is being looked at seriously beyond a few soundbites. I put it in the same category as Sunak justifying new oil licenses as making us more self sufficent for energy. Which anyone with even a minimal grasp of the facts knows is an outright lie.

Happy to be proven wrong.

Yes, but really depends on how much work the property needs to make a difference. To get my 1870's house up to an acceptable standard is more about comfort and convenience than a realistic payback time. I might get the investment back should I sell or rent it, but the cost of the improvements will take a very long time to be recouped from heating costs. From a policy point of view, of course, it being cheaper for me to burn gas than to improve insulation is not good.

We have one and its excellent. However, we have triple glazed windows, 25cm insulation jacket on the outside walls, plus underfloor heating. It uses around 4000kWh per year, most of which occur during winter. Outside temps are between -20 and +40. The system runs at 50 degrees for HW and depends on outside temp as to what temp it runs the floors. Once the structure is warm, the energy usage is very little.

ETA: I think it is excellent. I would probably not retro fit one without doing insulation, windows, and UFH.

Perhaps someone should invent "dishwashers".

Been waiting for that for a while - he's squeezed the heck (efficiency wise) out of a glow worm boiler and he'll do the same with a AHSP

Increasing the temperature of your water cylinder is an easy way to make your hot water last longer. The losses from a modern decent cylinder are pretty marginal in any case so there's not a huge saving to be made there anyway.

I tend to leave ours at 60 if it's just the two of us but if we have visitors I crank it right up as high it can go - makes a huge difference to the ability to have repeated back to back powerful showers. That's with an oil boiler, not sure how an ASHP would enjoy the same scenario.

My parents have underfloor heating and their main issue is the time it takes to get the slab to cool down - if the sun comes out during cold weather the additional solar gain on top of the heat output from the warm slab turns their house into a sauna and they end up with the windows open!

50 deg is borderline for scalding IMO - this suggests your hands have been conditioned to hot work or your water isn't as hot as you think it is

Are you a girl? My hands are certainly not leather skinned and 50C is absolutely fine. I wash my jeans and cottons at 50 and they don't come out the other end the size of a postage stamp when finished, which tends to support my claim that 50 isn't hot!

The other guy makes a good point about legionnaire's, running the water so cold.

RE hot water running out:
We have a 320L tank. But if you need a lot of HW, there is a “powerful” setting. It seems to produce water at the rate it’s being used. I have a wife and two daughters. They regularly have a bath and then two have a shower, then I shower and it’s fine.

In any case, 50 degrees is way hot enough for HW.

Our hot water is also mains pressure.