This is a bit of problem , as if not careful installation (to an old distribution board) could cause fairly regular imbalances , particularly when tasked with starting from cold/with cold water.

I know the manufacturers have gained CE marking , but I think we need some clear guidance form the IET now on this.

I know some comments don,t like wet system electric boilers , and if you have a home pre 2000 , gas is much cheaper from the heat perspective , however that may change. My home is fully electric and not very thermally efficient so i know a little about how the 4 months dec to march can feel.

Installation wise , you cant really use the din rail on a distribution board , so should be a separate switch near distribution board (and it perhaps should also feed the water pump) , however 40amp may not be enough , and finding a 50 amp is not easy , the manufacturer should have recommended unit to use , so perhaps give them a call. High amp fuse is an interesting choice , and car chargers (if they do get to home charging) will need something similar. 

Basically I think the IET need to have a discussion , I think we need something that is for new build , and something for retro fit, and we need to nudge the elctrical components people quickly , before we see high amp single spurs , causing affects on distribution boards , that could be affected , or even if we start having scenarios  where we affect the 100A distribution fuse.

In theory an electric wet system (and thermal losses of the building are key whether gas or electric ) , might not be too bad 150w water pump included on top of 12000w , providing you have thermostatic control , and keep it low 18oC. The real problem will be homeowners who run central heating at 22-24 , in a thermally inefficient home , and any external temperature below 5oC  , or if your tasking the system with hot water provision. With a quality gas boiler at £1400 the electric replacement should be around £500 , and if your really going electric , you have to ask the gas board to disconnect you (and remove the meter) to not pay further standing charges , actually removing your gas pipe to your property is lot more expensive and difficult.

In a well thought new build home an electric wet system should not be problem , one new 3 bed house i have looked at , was thermally efficient and 9kw would probebely do it as you can attain much more stable temperatures , so for new homes a wet system may well work.

I used some top of the range German fire clay inner radiators , and they have worked very well and i have run various experiments on efficency , from timing , to temperature set , and for me (and my thermally inefficent house) i try and set them in winter to back ground low heat and get by , but in a minus 5oC couple of days , things were not really as i would have liked , but most minus oC events are ok .

In bigger picture use of electricty for electric heating , for low income households needs looking at , and for the many 3 , 4 bed houses built before 2000 , who go to full electric heating , thermostatic control systems are a must.

The other thing is that its not just about keeping people warm , older houses may suffer slight damp and heating in some ways can be seen as good maintenance practice.          

This is a bit of problem , as if not careful installation (to an old distribution board) could cause fairly regular imbalances , particularly when tasked with starting from cold/with cold water.

I know the manufacturers have gained CE marking , but I think we need some clear guidance form the IET now on this.

I know some comments don,t like wet system electric boilers , and if you have a home pre 2000 , gas is much cheaper from the heat perspective , however that may change. My home is fully electric and not very thermally efficient so i know a little about how the 4 months dec to march can feel.

Installation wise , you cant really use the din rail on a distribution board , so should be a separate switch near distribution board (and it perhaps should also feed the water pump) , however 40amp may not be enough , and finding a 50 amp is not easy , the manufacturer should have recommended unit to use , so perhaps give them a call. High amp fuse is an interesting choice , and car chargers (if they do get to home charging) will need something similar. 

Basically I think the IET need to have a discussion , I think we need something that is for new build , and something for retro fit, and we need to nudge the elctrical components people quickly , before we see high amp single spurs , causing affects on distribution boards , that could be affected , or even if we start having scenarios  where we affect the 100A distribution fuse.

In theory an electric wet system (and thermal losses of the building are key whether gas or electric ) , might not be too bad 150w water pump included on top of 12000w , providing you have thermostatic control , and keep it low 18oC. The real problem will be homeowners who run central heating at 22-24 , in a thermally inefficient home , and any external temperature below 5oC  , or if your tasking the system with hot water provision. With a quality gas boiler at £1400 the electric replacement should be around £500 , and if your really going electric , you have to ask the gas board to disconnect you (and remove the meter) to not pay further standing charges , actually removing your gas pipe to your property is lot more expensive and difficult.

In a well thought new build home an electric wet system should not be problem , one new 3 bed house i have looked at , was thermally efficient and 9kw would probebely do it as you can attain much more stable temperatures , so for new homes a wet system may well work.

I used some top of the range German fire clay inner radiators , and they have worked very well and i have run various experiments on efficency , from timing , to temperature set , and for me (and my thermally inefficent house) i try and set them in winter to back ground low heat and get by , but in a minus 5oC couple of days , things were not really as i would have liked , but most minus oC events are ok .

In bigger picture use of electricty for electric heating , for low income households needs looking at , and for the many 3 , 4 bed houses built before 2000 , who go to full electric heating , thermostatic control systems are a must.

The other thing is that its not just about keeping people warm , older houses may suffer slight damp and heating in some ways can be seen as good maintenance practice.