Bigger Supplies Needed.

70kW for a domestic? Presumably someone's making the mistake of thinking that heat pumps should be a direct replacement for gas boilers in uninsulated homes - rather than upgrading the insulation to a sensible level first.

   - Andy.

"Well son, three phase is a stronger sort of electricity used in industry. Some people are frightened of it, but nothing actually prohibits domestic use.

Some people think that outlets connected to different phases must be kept 2 meters apart, but that regulation was abolished about 50 years ago"

On the face of it, three 100 A fuses give you 69 kVA, but I doubt that such a high power ADMD would be agreed with the supplier.

69 kVA for, say 12 hours a day for 3 months, would cost about £15k!!!

Well to compete with the temperatures achieved  by gas heating in solid walled houses the price of leccy needs to come down a lot, to be the same as or cheaper than gas per kW. Or as noted above we need to start demolishing older housing stock, and rebuilding with cavity walls that can be insulated and so on. If not there will simply be a lot of cold houses, or at least ones with only one heated room. However, folk have lived to a ripe old age like that in the past, so they may well do so again - most if the UK housing stock not only pre-dates WW2  it also pre-dates central heating...

At the daily mail level that's not such a bad description of a 3 phase supply considering the sort of dogs dinner we usually get when they try to describe anything technical.

3 phase need not be stronger. Plenty of the world gives 3 phases at 32A per phase in places where we would have 1 at 100A, it just makes for more flexible meter tails and lower pscc.

Oddly I was disabusing someone of the 6 foot rule only the other day in relation to two sockets in the same lab -they wanted to make an HS near miss, it isn't.

And even when it was a rule, all it needed was a warning label, and phase barriers inside switchgear supplied by more than one phase - we had plently of places where alll 3 phases came into the same box.

Mike.

Or as noted above we need to start demolishing older housing stock, and rebuilding with cavity walls that can be insulated and so on.

Actually a lot can be done while retaining the original structure - I've taken a 1910 build stone house that a 24kW combi struggled to keep warm and insulated it so that I now reckon 3kW keeps it toasty warm even on the coldest Yorkshire days. It was certainly a lot of work and a lot of disruption, and I was aided by a few features that made it easier (e.g. no internal doors adjacent to outside walls), but it is possible.

   - Andy.

Would I be correct in assuming that you put insulation inside the walls? Not possible in my house without ripping out the high skirting boards, dado rails, picture rails, and cornices!

In response to Mike, I am rather fed up of people in the media bleating about only being able to afford to heat one room. What do they think that we always used to do?

Dunno -  as a child I well remember drawing in the ice on the inside of the bedroom windows for a few weeks a year. My grandparents also had a paraffin heater in the outside loo that got lit at bedtime if the forecast was for ice, though that was not for our comfort, (humans had a gazunder after all ) , but really to stop the cistern freezing, and they had a portable gas fire that they used to lug from room to room in the event of visitors and gas taps near the fire places in the main rooms and one in the bathroom that the rubber hose could be connected to.  It got condemned during the change over to north sea gas, so then after a year or two more they had a boiler installed and moved into the 1970s.
Mike.

Would I be correct in assuming that you put insulation inside the walls? Not possible in my house without ripping out the high skirting boards, dado rails, picture rails, and cornices!

Internal insulation - i.e. Insulation on the inner faces of external walls (as distinct from inside the wall cavity), yes. And yes it was a lot of disruption. In our case much of the original lime plasterwork had perished and the joinery had seen better days so stripping back to brick/joists was on the cards anyway. Yes we lost the original plaster cornice ... but I was able to reinstate them with modern reproduction fibrous ones which don't look at all out of place. The new skirting boards are just as tall as the 1910 originals (you do have to shop around for them though). And insulation under the downstairs floors, and under the roof, and 0.8U value windows.

External insulation would probably have been a lot easier, cheaper and technically better (keeping the thermal mass inside), but as it was a stone built house in a conservation area that option wasn't open to us.

I guess the point I was making, is that it is possible and still a lot less disruption (and cost) than demolishing and rebuilding. There's actually quite a lot of renovation going on - bathrooms and kitchens seem to be stripped out completely every couple of decades (or so it seems), it's not uncommon in older housing to get walls and ceilings re-skimmed before redecorating - if the 'norm' became adding insulation whenever the opportunity arose (e.g. when the walls were bare anyway, or add insulation backed plasterboard rather than just skimming) some significant improvement could be done with relative ease. It needs to be done to a plan though - a bit pointless adding little bits of internal insulation if next step was proper external insulation.

   - Andy.

I think part of the problem is that there is not a one size fits all solution to this  - at best there may be 'cookie cutter' recipes for certain types of building on mono-cutlure housing estates.
Clearly you are capable to organise/oversee what is in effect your own bespoke design, as I suspect many on here might be, but that will not be the typical householder, at least not without a lot of support (given the number of heating timers out there whose owners cannot work out how to program them, there is quite a lot  missing at the bottom of the understanding ladder in many cases ).

This lack of understanding seems pervasive, and it is very telling that  it can be quite tricky getting an accurate energy rating assessment done on any building that is a bit non-standard - even the folk who have  been on the course seem unable to articulate what is happening  beyond 'computer says no!'

For a generation, maybe more, adding heating has only meant installing radiators and a gas pipe, and making a hole for the flue in a place that does not violate the rules reproduced on the back page of the makers instructions. Considerable upping of the game will be needed to avoid a lot of wasted effort.

Mike.

(proud owner of a recent extension where the really well insulated ceiling stops at the inside blockworks, so  there is gap between the cavity insulation and the ceiling - result a melted outline stripe on the flat roof in winter and cold tops to all the walls. doh!  - had I been around that would not have happened, but it did.)

Or we could keep warm by gluing our hands together.

www.dailymail.co.uk/.../Insulate-Britain-protesters-face-court-alleged-injunction-breach.html