100% Electric on low incomming supply options?

Hellsteeth

I would be interested in people’s opinion in my situation to improve my heating comfort and efficiency of a property I have purchased.
The property is probably about 250 years old in rural France. It has no Gas, LPG or Oil and therefore no existing installed wet radiator system.
It is fed via three phase power with a maximum of 4KW per phase.
Currently the property is heated with a combination of wall mounted 2KW thermostatic heaters and a large (approx 12KW) wood burning stove. Not all the heaters can be used at the same time due to the limited supply.
The floor is solid stone with clay tiles on top and therefore cold to the touch.
The walls are insulated with a something like polystyrene balls in the cavity.
It is all double glazed.
I have about 3 acres of land and a small stream running through the property.
As the property is long and thin with bathrooms at each end I have two 150L water tanks with immersion heaters. The tanks are at separate ends of the property.
Currently I am on the French equivalent of Economy 7 except it is split into two time periods. It is cheap rate between 0230 and 0630 and then again between 1200 and 1500.
I have considered a ground source pump from the land or stream but believe the house is not really insulated enough and would be cost prohibitive to put in under floor heating.
I have considered a back boiler from the wood burning stove to heat water and maybe three radiators but also want something autonomous for frost protection when the property is empty.
I have read through a lot of this forums view on the various new heaters on the market and their dubious energy efficiency claims. I do however like the controllability concept some of them have for connecting them all together in a wireless network altering temperatures of individual heaters or zones during the day as rooms are used and unused.
This leads me to believe I should go for modern night storage heaters, especially as I am able to give them a mid-day top up between 1200 and 1500.
However and here is my real question. As I am limited to just 4KW per phase, I would be unable to run more than three medium sized ones at once. The house is 100% electric so that means the heating has to compete with cooker, washing machine, drier, kettle, hair drier, hot water immersions etc.
Nothing prevents me from putting in an oil or LPG tank and a traditional wet system of course. I just feel this must be a reasonably common issue to remain electric on a limited supply with a very controllable system that allowed the heaters to be used in rotation so not tripping out the incoming supply.
As mentioned at the start I would welcome some pointers.

lovesgshp

You have a 12Kw 3 phase supply then, or am I missing something?

Cardew

Geotherm wrote: »

You have a 12Kw 3 phase supply then, or am I missing something?

In France you pay a higher tariff for being able to draw more supply from the mains supply. i.e. someone who is limited to a 12kW supply will pay considerably less than someone who elects to be able to draw, say, 20kW from the mains.

To the OP.

You refer correctly to dubious energy efficiency claims. As said many times on this forum all electrical heating is 100% efficient and you get out exactly the same heat from ANY electrical heater.

I would have thought that storage heaters would be the worst possible appliance for you being absent from the property. They will use xxkWh of electricity regardless of the temperature inside or outside.

It seems to me what you need is simple heaters wired through a Froststat. All UK houses with gas CH should have a thermostat that cuts in when the temperature drops sufficiently and there is a possibility of it freezing - I have mine set to 3C.

Very simple and cheap enough that you could have them in several zones.

http://www.bhl.co.uk/product/HWELL_T4360A_1009_FROST_STAT_240V

lovesgshp

In France you pay a higher tariff for being able to draw more supply from the mains supply. i.e. someone who is limited to a 12kW supply will pay considerably less than someone who elects to be able to draw, say, 20kW from the mains.


Similar here Cardew. We have 15Kw 3 phase supply. Norm is 3 - 6 Kw. We have to pay per Kw supplied.

Cardew

Geotherm wrote: »

Similar here Cardew. We have 15Kw 3 phase supply. Norm is 3 - 6 Kw. We have to pay per Kw supplied.

You still of course pay for each kWh consumed.

The problem with Storage heaters is their complete lack of flexibility.

Of course much depends on how long the OP is in residence. However it would be a nonsense to have to 'charge them up' every day just in case they were needed.

Owain_Moneysaver

Air to air heat pump
Solar thermal for hot water

For frost protection you need very little electric heating on a frost stat.

However your first priority must be to insulate - can you lay a layer of insulating board over the existing floors? Do you have loft/ceiling insulation?

Hellsteeth

Thanks for the quick replies.

To Geotherm: Yes it is 12KW 3 phase, 60 Amps on the main breaker. But if I exceed 4KW on any one phase I lose all three phases.
I am using a 'delesteur" that deselects or cuts in at just under 4KW and cuts out the heating in order to avoid trips.

To Cardew: I had not thought of the storage heaters using power when the property is absent. This is a good point I had not considered.

To Owain Moneysaver: The floor is very old and would be a real shame to dig it up. We do have some thick rugs down covering a lot of it.

Controllability seems to be the key whatever the system.

lovesgshp

Why not go for a 3 phase air/water heat pump? I don't know the size of the property, but it may be a good option.
You could use a ASHP or a GSHP to run radiators if you get the right spec. unit.
Comment below from a client of ours here, GSHP with rads, low insulation property.

Everything seems to be working a treat, we are delighted with it all. We got our first bill today for a month, considering we had to put it on pretty high at the beginning and assuming the cost will be much less in the summer months at euro 311 I think not bad. We should achieve about a 50% saving compared to the gas. It is also working well with the timer so we have it working as much as possible in the night and that seems to have helped since the cost is split in the three phases of the day. We really like the way it heats and maintains the warmth at a lower temperature than with the gas.