Going over to Electric - Does a houshold supply need upgrading?

[Rich1982]

Not a DIY question as such, but a request for upgrading advice. I'm scoping out the costs involved in moving my home my away from fossil fuels and going fully electric.

My concern is am I likely to need to spend a lot of money upgrading the existing domestic power supply to 3 phase in order to achieve this?

I currently have a standard 80amp domestic supply (the main fuse states 80amp, the consumer unit indicates it is rated upto 100amps).

My home is a standard 3 bed property containing the ordinary appliances (washing machine, tumble dryer, fridge freezer, kettle, microwave, etc). I currently have an electric oven and hob for cooking, plus an 8kw electric shower.

Adding-in a heat pump with a max rated current requirement of 20 amps from the consumer unit; will that be feasible within the existing supply / consumer unit set-up, or will I need to factor in having the power system ugraded? I'd assume if an upgrade is required that would be to 3 phase, which I hear can be very expensive. Also, if this is feasible on the existing supply, if I then wished to add-in a charging point for an electric car at some point in the future could that realistically be accomodated as well?

Apologies if these are stupid questions. With the push toward electric homes it seem unlikely that everyone is having expensive upgrades to 3 phase put in, but it feels like there may be a risk of getting close to the 80amps provided on the standard supply.

I'd be grateful for any direction on this.

 

[johnb2713]

You'll be fine.

In all likelyhood your supply can be upgraded to 100 amps by changing the fuse, my DNO did this FOC.

The 20amps for the heatpump will be peak current during startup, not the constant running load unless it's a huge heatpump.
Car charger will be fine, most of the decent ones (ZAPPI) has the ability to reduce load dependent on grid load.

I have a lot of electrical load here including heatpumps, I can if I really try max out my mains supply, I've had it at around 105 amps for a short time, the service fuse takes ages to blow, even at 20 amps over it can take 90 minutes!

 

[Murdoch]

I would question the logic of this change.

Its approximately 3x the cost to heat using electric over gas AND don't forget that lots of electricity is still generated using fossil fuels

 

[johnb2713]

I would question the logic of this change.

Its approximately 3x the cost to heat using electric over gas AND don't forget that lots of electricity is still generated using fossil fuels

Aye if it's resistive heating possibly. If on the otherhand heating is done by Heatpump or by a ZEB like Tepeo then what you say isnt true.
In terms of burning fossil fuels for electricity, most of the electricity is generated with renewables and that is getting better every week.

 

[Murdoch]

Aye if it's resistive heating possibly. If on the otherhand heating is done by Heatpump or by a ZEB like Tepeo then what you say isnt true.
In terms of burning fossil fuels for electricity, most of the electricity is generated with renewables and that is getting better every week.

maybe Let’s let the op respond ?

and as for lecky generated by renewables - don,t get too excited as importing wood pellets from America isn’t very green either

 

[Andy™]

Its approximately 3x the cost to heat using electric over gas

only if you are using resistive heating, i.e panel heaters. using air / ground source heat pumps are very efficient. not sure exact ratio of electric / gas consumption though, but definitely not 3:1

still right on where the leccy comes from though, although more and more is from green sources but still a long way to go yet before saying its fully green sources

 

[johnb2713]

maybe Let’s let the op respond ?

Of course, just wanted to present a balanced view!

and as for lecky generated by renewables - don,t get too excited as importing wood pellets from America isn’t very green either

Yes I'm aware of Drax but there are lots of other power generators in the UK, and as you quite rightly said lots of electricity is generated by polluting fuels BUT a greater amount is produced by renewables which you omitted to mention (bottles half empty rather than bottles half full mode).

 

[johnb2713]

only if you are using resistive heating, i.e panel heaters. using air / ground source heat pumps are very efficient. not sure exact ratio of electric / gas consumption though, but definitely not 3:1

Heatpumps usually run between a COP of 2 and upto 4.5 dependent on outside air temp and flow temp. Gas boilers on the otherhand tend to run around 80 to 85% for a condensing boiler, much worse for a non condensing one. These figures need factoring in when considering heatpumps etc. So if gas is 10p kWh, correcting it for boiler efficiency would give you £12.5p per kWh of heat, a heatpump on a standard tariff say 30p would give you 10p per kWh of heat. If you have solar or battery then it really does come into its own, in my case 2.5p kWh heat.

still right on where the leccy comes from though, although more and more is from green sources but still a long way to go yet before saying its fully green sources

And it's not what I said!

 

[Mr Aargh]

Get solar. Lose the shower and change to an unvented mains pressure cylinder (at least 240 litre) . Heat your water most of the year with a solar Iboost.
Regardless of efficiency, it costs about 15kwh to heat from stone cold the cylinder. This on a Night time 20p flux tarrif is about 3 quid. Roughly same cost as gas would be.

 

[Mr Aargh]

Also I disagree regarding 80w fuse being enough. You divide load by 240. Your shower 8000w plus the car charger 6700w plus a washing machine 2600w and someone else using the kettle 3000 will overload that fuse because 20300w /240 is 84.583 amps. The shower is ridiculous and too costly. Change to a cylinder and system boiler plus solar and Iboost.

 

[johnb2713]

Also I disagree regarding 80w fuse being enough. You divide load by 240. Your shower 8000w plus the car charger 6700w plus a washing machine 2600w and someone else using the kettle 3000 will overload that fuse because 20300w /240 is 84.583 amps. The shower is ridiculous and too costly. Change to a cylinder and system boiler plus solar and Iboost.

Well Mr Aargh you maybe should do a little more research rather than relying on gut feeling.

The fuse characteristics in service head you will see that an 80amp fuse with a 100 A current will take 2.7 hrs to blow, 180 amps it will blow in 2 minutes, with 84 amps it wont blow. You also need to consider how likely it is for someone to be using 8kW shower whilst the car is on charge, the washing machine just happens to be taking maximum load at that time and somebody else is boiling the kettle. even if were to go on for several hours in this state, the fuse still wouldn't blow hence my advice the OP had little to worry about but request the upgrade anyway.

 

[Rich1982]

Thank you for the advice chaps I'm very grateful.

Where we live there is no mains gas, so the choices are a little more restricted and each come with their own pros and cons (heating oil / LPG / electric).

Oil and LPG both require ordering an storage, but more crucially, unlike mains gas and electricity haven't been on any form of price cap.

It's not really an eco decision, more around practically and governments and parites of all flavours seem fairly set that this is the way things are going.

The water question is a very interesting one that's been raised. I'd understood on-demand electric heating was considered much more efficient? Whilst it's high draw in the moment of being heated, you're not heating water in a big tank and keeping it on the boil for 24hrs say just to have a 5 minute shower (I'm aware that it's not kept literally boiling, but at 50 degrees or whatever it is). Is that incorrect??

Rich

 

[Murdoch]

Get solar. Lose the shower and change to an unvented mains pressure cylinder (at least 240 litre) . Heat your water most of the year with a solar Iboost.
Regardless of efficiency, it costs about 15kwh to heat from stone cold the cylinder. This on a Night time 20p flux tarrif is about 3 quid. Roughly same cost as gas would be.

There’s no way you will heat your hot water “most of the year”

 

[johnb2713]

Thank you for the advice chaps I'm very grateful.

Where we live there is no mains gas, so the choices are a little more restricted and each come with their own pros and cons (heating oil / LPG / electric).

Yep, youre pushed down a single path really, no-brainer.

Oil and LPG both require ordering an storage, but more crucially, unlike mains gas and electricity haven't been on any form of price cap.

Oil and LPG have always been expensive, I had LPG in the early 80's it was horrific.

It's not really an eco decision, more around practically and governments and parites of all flavours seem fairly set that this is the way things are going.

Nah, take the Brownie points, be an eco warrior for this ~

The water question is a very interesting one that's been raised. I'd understood on-demand electric heating was considered much more efficient? Whilst it's high draw in the moment of being heated, you're not heating water in a big tank and keeping it on the boil for 24hrs say just to have a 5 minute shower (I'm aware that it's not kept literally boiling, but at 50 degrees or whatever it is). Is that incorrect??

Electric heating is pretty much 100% efficient, storing the water in a tank does create some losses BUT it does enable you to harvest the energy from Solar. With modern tanks the energy loss is minimal, my wife complains that the airing cupboard doesn't get warm any more with our new tank. If you have space for a tank, do fit one it's better all round.

 

[offgridAndy]

FYI I had a LPG tank installed in the spring. 2800 Ltr bomb installed FOC and gas service supply pipe installed to house. We did the ground works and concrete base. I have a fixed rate contract for the LPG supply for the next 2 years 60p per ltr. If I had been an existing customer and had transfered over from Calor the price per lire would have been 50p. So in comparrison with oil the LPG cost is OK, plus cleaner and no filters to keep clean. Don't discount LPG automatically, it depends on your choices available.

 

[johnb2713]

FYI I had a LPG tank installed in the spring. 2800 Ltr bomb installed FOC and gas service supply pipe installed to house. We did the ground works and concrete base. I have a fixed rate contract for the LPG supply for the next 2 years 60p per ltr. If I had been an existing customer and had transfered over from Calor the price per lire would have been 50p. So in comparrison with oil the LPG cost is OK, plus cleaner and no filters to keep clean. Don't discount LPG automatically, it depends on your choices available.

Currently, according to official government data, the cost of gas between July to September 2023 shows that the UK averaged 7.15p per kWh for gas. LPG currently averages at around 12.2p per kWh. So, LPG is almost double.
Using an off peak tariff and/or solar and battery to run a heatpump or a ZEB boiler like Tepeo makes a lot more sense and of course it's greener than gas.

 

[binky]

The water question is a very interesting one that's been raised. I'd understood on-demand electric heating was considered much more efficient? Whilst it's high draw in the moment of being heated, you're not heating water in a big tank and keeping it on the boil for 24hrs say just to have a 5 minute shower (I'm aware that it's not kept literally boiling, but at 50 degrees or whatever it is). Is that incorrect??

Rich

you can get small unvented cyclinders with say 15 litres of stored hot water - enough for a sink full of water or very quick shower. These tend to be in the 1.5-3 kw range, so would work better with solar outputs. Temperature ca be set to be around 50C or higher. On demand is basically electric shower in a box, so 7-9 kW is quite normal