SteamyTea

That goes back to the old central heating method of always having the small bathroom radiator on, regardless of what the rest of the radiators were up to. Then put the thermostat in the coldest, unheated corridor. The problem with not zoning is that you can easily have uneven temperatures. Take my house, the rear is NE facing, so cold, front is SW facing, so warmer. Add in afternoon solar gain, even on a day like today, and the front can get quite comfortable while the rear is cold. That crossed my mind as well. Could do it on just times, say 40 minutes downstairs and 20 upstairs. Just a valve on a timer then.

The buffer/volumiser side is something that crossed my mind as well. How sensible is it to run a heat pump (or any 'boiler') very close to the minimum volume. My feeling is that it is a bit like running a car at the lowest oil, or coolant, levels. Possible, but probably not really the best thing to do if you can add a bit more easily.

I have been pondering that as well.

Yes, but I think a lot of that is down to the UK having oversized, but highly modulating, gas boilers. To run less controlled zones relies, more and more, on a decent room by room heat loss calculation. This becomes harder with UFH as you can only change the flow rate and flow temperature, you can't change the size of the emitter.

Sadly true. It used to be so good for the sports coverage.

As warm air rises, have you checked the air temperature up there? You may find a ceiling fan can shift enough to raise the temperature lower down. You could try it out with a desk fan first if you have one.

Emptied his sack.

I have done every panel on my car, where I live is like Stapleford, it is the place that stolen cars get torched.

They should give then automatics/EVs.

Not really. All the 'solar houses' books I read 20 years ago when studying this area were all a bit flaky and 'it will be alright'. Geometry and physics is really all that is needed. And a spreadsheet.

Where is it all going, downwards?

High temperature UFH is not the best, higher losses to the ground, not so nice to walk on in bare feet.

? Slow flow rate or high flow temperature.

Yes, you are right. Anyone else got one as it would be interesting to know how good, or bad, they are.

Yes. The best correlation was with AT difference, rather than just OAT. Probably more true in places that have prolonged periods below 0°C. The problem with cramming in as much energy in as shorter time is that it requires a larger output heat source and room for the storage. This penalises smaller houses. For my climate, as I said in my analysis, ToU probably does not make much difference. Out of the 2152 hours I have had my heating on, only 676 hours were 4°C or less (31.4%). 325 hours and I did not need heating as it was over 9°C (my mean switch on temperature) that is 15% of the time. Of course, having storage heaters I don't have the luxury of stopping output fully, so the room temperature just rises a bit for a few hours. Most of those few hours, the excess heating is during the day, when it is most useful and does not cause excessive heating, My mean room temperature, when it is 4°C or below, it is 18.6°C, when it is 5°C and above, it is 20°C (which is my target temperature).

Welcome. What thickness Celotex did you fit and did you fit a vapour control layer (VCL) and what are you doing to heat the space?

Would Shelly relays suffice? If you initially want to keep the storage heaters (as you have them and you are doing other work), remote control relays should do the trick. You just reduce the hours they are running to limit the input/output. The only thing I would worry about is how well they deal with a power cut. Do they reconnect easily and reliably?

You can get them, our old mate @Jeremy Harris had one. Can't remember the make. Think it was only 2 kWp, which would me useful in my house, but for larger properties several may be needed.

Shall have a look when I get time/bored. Currently looking at the temperature and energy distributions.

With UFH it is really down to how much insulation you can get under it. I suspect that radiators are going to be your best option. But still add floor insulation if you can. If you can put up with a bit of noise, and the new room/s are not constantly used, then plinth/fan assisted radiators may be an option. They take up less space.

Should always be the first thing to do.

Worth reading as it has some notes and comments that explain a lot of it.

One way to increase the efficiency of an ASHP is to increase the size of the external heat exchanger (the radiator). Our planning system puts a limit of 0.6 m3 for a permitted development unit I think though.