Air Sourced Heat Pump.

we also need to know the outside temperature acceptable to achieve this, and I suggest that in the UK on average this should probably be accepted as -10C.

That does seem rather pessimistic. All the heating design guides I've seen suggest something more like -1°C for warmer parts of the UK to -5°C for the cooler parts. That's not to say that the temperature never falls below that, of course it does, but when it does for most of us it's only for a few hours overnight on a few occasions a year - and the short periods where heat loss exceeds maximum heat input doesn't lead to instant catastrophe - but rather the thermal inertial of the building carries things across in exchange for a small drop in room temperature. In many areas we only design for perhaps 99% of situations - the extra cost for covering the final 1% is very frequently not justifiable.


I agree that wet UFH isn't very responsive - I've got it at home (under timber floors running from a thermal store, blended down to just below 40 degrees) - as a result we mostly just have all the room 'stats set to a constant setting all day - ignoring the programmable features)  - but that's not to say it runs 24x7 - it only does that on the coldest days in winter - for the rest of the year the thermostats regulate it down.

 

Heat up time nearly infinite because the heating has forgotten the thermal mass

Only if you're trying to heat the house up from stone cold on the coldest winter days -  in reality that almost never happens (it would be a disaster for the plumbing anyway as the pipes would be frozen) - in all other cases the heat loss would be less than the heat input.


I think we're looking at this the wrong way around anyway. The problem isn't to replace gas with electric and guarantee the same level of service. I think we should recognise that "society" (well, the majority of scientists, all of government and an increasing number of the general populace) have concluded that continuing to burn fossil fuels is a very bad idea and needs to stop. That's "society's" top priority. Ideally that should happen in a minimally disruptive way of course, but if there are to be compromises, then so be it, but the priority remains. A bit like when society decided to outlaw slavery - that was the principle they took - undoubtedly someone pointed out that technology of the time couldn't possibly replace slave labour with anything mechanical and enticing free workers into doing the work previously done by slaves would clearly be impossible. But such arguments missed the point - society stuck to its principles and just accepted higher prices and lower supply of the likes of cotton, sugar and tobacco (and everything else previously produced by slave labour).


By all means point out that in the "brave new world" if you don't have a properly insulated house you'll be less comfortable at times (and have to put on a jumper or resort to only heating the rooms you're actually using like our grandparents did). But let's put our best efforts in solving the inevitable problems rather than just hoping the problem will just go away, as it seems it won't.


   - Andy.

we also need to know the outside temperature acceptable to achieve this, and I suggest that in the UK on average this should probably be accepted as -10C.

That does seem rather pessimistic. All the heating design guides I've seen suggest something more like -1°C for warmer parts of the UK to -5°C for the cooler parts. That's not to say that the temperature never falls below that, of course it does, but when it does for most of us it's only for a few hours overnight on a few occasions a year - and the short periods where heat loss exceeds maximum heat input doesn't lead to instant catastrophe - but rather the thermal inertial of the building carries things across in exchange for a small drop in room temperature. In many areas we only design for perhaps 99% of situations - the extra cost for covering the final 1% is very frequently not justifiable.


I agree that wet UFH isn't very responsive - I've got it at home (under timber floors running from a thermal store, blended down to just below 40 degrees) - as a result we mostly just have all the room 'stats set to a constant setting all day - ignoring the programmable features)  - but that's not to say it runs 24x7 - it only does that on the coldest days in winter - for the rest of the year the thermostats regulate it down.

 

Heat up time nearly infinite because the heating has forgotten the thermal mass

Only if you're trying to heat the house up from stone cold on the coldest winter days -  in reality that almost never happens (it would be a disaster for the plumbing anyway as the pipes would be frozen) - in all other cases the heat loss would be less than the heat input.


I think we're looking at this the wrong way around anyway. The problem isn't to replace gas with electric and guarantee the same level of service. I think we should recognise that "society" (well, the majority of scientists, all of government and an increasing number of the general populace) have concluded that continuing to burn fossil fuels is a very bad idea and needs to stop. That's "society's" top priority. Ideally that should happen in a minimally disruptive way of course, but if there are to be compromises, then so be it, but the priority remains. A bit like when society decided to outlaw slavery - that was the principle they took - undoubtedly someone pointed out that technology of the time couldn't possibly replace slave labour with anything mechanical and enticing free workers into doing the work previously done by slaves would clearly be impossible. But such arguments missed the point - society stuck to its principles and just accepted higher prices and lower supply of the likes of cotton, sugar and tobacco (and everything else previously produced by slave labour).


By all means point out that in the "brave new world" if you don't have a properly insulated house you'll be less comfortable at times (and have to put on a jumper or resort to only heating the rooms you're actually using like our grandparents did). But let's put our best efforts in solving the inevitable problems rather than just hoping the problem will just go away, as it seems it won't.


   - Andy.