Going Electric - going green?

I am currently in the dark ages - solid fuel boiler supplies hot water and radiator system heating. No gas to the property which is 100 years+ old. Solar company has not quoted as the house would be marginal, I am sceptical about a heat pump. So have considered electric boiler to run the current wet radiator system.
Pros: cheapest system to install. Least disruptive system to install. Clean and easy to run. (Get rid of my coal bunkers!). Can run on renewable energy.
Cons: Electric boiler not officially considered green. Electricity is very expensive. System will be expensive.
Your thoughts, experiences and advice would be appreciated


The principles behind them are very well understood. And you almost certainly have at least one in your house already - your fridge. If you have a hot water cylinder, then you have may have two (the water in the cylinder is often heated indirectly from the heating).

I’m planning on fitting a heat pump when my gas boiler comes due for replacement (or possibly earlier if I get to house renovation first).

Solar Thermal might be an option for you too.

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Just to let you know, I’ve had a Mitsubishi heat pump for 2 winters now, has been great, with no issues at all. heats water to 50C constantly. Do know that your radiators will likely need to be replaced with larger, double covector designs to maximise efficiency. If you curious about energy usage, have a look at this (a year with this heatpump):

My only worry with your properties is that you say it’s over 100 years old, so I can’t imagine it having the best insulation, which heat pumps need to be efficient. The worst case is that it costs the same as a conventional electric boiler. If your really concerned about reliability, you can connect multiple backup heaters to most systems, in case of a failure or if it suddenly goes to -30*C (lol). I can even connect a convential boiler to my system and run it in hybrid configuration


Don’t forget about this for the cost of the system

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Is that ground or air source?

Do you have a record of how much energy you used for heating before the heat pump was installed for comparison?

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Air source. Not enough space for ground and it would probably be too expensive. Unfortunatly we changed to a heatpump as soon as we moved in as we did not want to deal with storage heaters and economy 7. We did use the storage heaters for 1 night, and they used 48 kWh. and
3 rooms were not even heated. compare that to the same time with the heat pump keeping the house at 21C (warmer than the storage heaters) for 18 hours, than at 18C for the night

edit: thought it would be worth noting that this heat pump isn’t even being used in the most efficient configuration yet.


Thanks for replying. Concerns are the initial cost and need/advice to replace existing radiators; older property so insulation is an issue; government grant scheme seems to be a bit of a mess; haven’t been impressed by the companies I have spoken to.
Like you I do not have space for ground source, would want to hide ugly, noisy(?) air source.
If electric vehicles is the way to go why not electric boiler system?

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I haven’t started my research yet, but I understand there are some pile-like options for ground sources, which means the footage doesn’t have to be large. I don’t know whether vertical methods would work out cheaper or more expensive than digging up lots of ground to lay horizontal loops.

Also, how big is your property (if you don’t mind telling us)? (for reference, I use ~4000kWh pa on gas, ~95% of which is for heating, to keep a 3-bed semi warm enough for me [which is not very]. I suspect that’s quite low usage.)

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If it’s an older property, with older radiators, my understanding is that there’s a good chance they’d work out quite well. It’s modern, small-bore, radiators that are apparently not much use with heat pumps.

That’s an excellent question.

99% of people probably have an electric kettle, and electric showers often do their own water heating. And now we have those instant hot water taps as well. I wonder how efficient these appliances actually are? (I’d always assumed they were pretty good, but now you’ve got me thinking about it!)

OTOH, aren’t immersion heaters considered relatively expensive to run? (unless you use them on E7) And isn’t an electric boiler essentially a bigger version of the immersion?

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The looks are subjective. mitsubishi has some i actually think look modern and alright compared to the usual ac unit, but i can imagine on a older house that’s not that aim :

however the noise is something i want to debunk. These modern units are not noisy, i might record mine later if i remember. Its not an annoying noise anymore either, but a low-pitched hum. the noise of the air moving though the unit is louder then the actual compressor sometimes. In high demand, low outdoor temp situations, things can get a bit louder, but its never annoying. I have mine on the wall adjacent to my living room, and it never disturbs conversation or the tv, and we don’t feel any vibration . One thing you will want to conder is placement. Make sure that snow cannot restrict the heat pump . Snow is one thing that a heat pump will struggle to deal with, and will result in high noise, excessive defrosts and maybe even emergency heat (basically an electrical backup element) having to be used

We had a totally new centrel heating system put in because we had storage heaters, I would get advise from an installer weather you need to upgrade, You very likely will for efficiency’s sake. I could of had the flow temp (tempo of radiatiers) at 50C and had much smaller rads, but this isn’t as efficient as running them at 30 - 40 and having larger rads . The larger the radiator the better. Double convector radiators recommended. If you want a smaller footprint radiator in a larger room Fan assisted radiators like the I-Life2 can be an option though these are more pricy then conventional radiators, as well as having more heat output, they have the really interesting option of having a cooling mode. Most heat pumps are reversible, which means they can flip and become an air conditioner. These radiators further allow this to work because that have a fan (you cant use convection for cooling)

All interesting options in this modern world

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Id imagine getting a pile driving to make bore wells is more expensive then running an excavator, though like you i’m not sure

2 bed bungalow, which i appreciate is smaller then yours. One thing to note that this is consumed energy (how much its taken from the meter), not delivered energy (how much its put into the living space)

Kettles, electric showers and that sort of thing are all 100% (or very close) efficient. This is because that all the energy used is being turned into heat (what we want), none of it goes to sound or friction (things we don’t want). Heat Pumps get wacky with there 500% efficentys, where there able to get 1 kwh of electricity from the grid, and use that to get 5KwH worth out of the air. Weird stuff.

Most (at least modern) electric vehicles will actually use a heat pump, i know tesla as of late have switched to heat pumps on the model 3 and model Y. Resistive heating uses a ton of electricity, and is simply not sustainable for cost, and for the grid long term.

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Electric vehicles are very efficient at converting stored electric energy into movement of the vehicle resulting in very little energy being wasted as heat. An electric boiler simply converts electricity into heat. Other than accidental losses in pipes etc to space which doesn’t need heated they’re nearly 100% efficient. Almost everything ends up as heat eventually. A heat pump extracts energy from the air or ground, using electricity to run a compressor, pumps etc. More energy is extracted from the environment than the amount of electricity consumed and the total of consumed electrical energy + extracted energy goes into your house, minus various accidental losses. Most heat pump systems are capable of putting at least 3kWh of heat into a house for every 1kWh of electricity they consume. A simple electric boiler would put only 1kWh of heat into a house for every 1kWh consumed. Hence the attraction of heat pumps. In EV’s they are used for exactly the same reason, to minimise the energy drawn from the EV battery while heating, or cooling, the vehicle interior. A heat pump is however much more complex and expensive than a simple electrical resistive heater (wire in a waterproof tube).
Hope that helps.

Thanks for this. I am coming round to the idea. Just need to complete some building work and then reassess system requirements.

You’re welcome. If you’re doing building work in your house it’s a great opportunity to make it better for a heat pump, which is also better for any heat source. As other people have said, fit the biggest radiators you can. Fit two in a big room to make the heating more even. Underfloor heating is the ideal but pretty difficult to retrofit well. The reason for big radiators is to keep the circulating water temperature (the flow temperature of the heat pump / boiler) as low as possible. The efficiency (Coefficient of Performance) of a heat pump reduces with the difference between the input and output temperatures. So, keeping the flow temperature low lets the heat pump use more energy from the environment (air/ground). Most conventional central heating systems have the smallest possible radiators because they’re less expensive, easier to handle and don’t take up as much room space, with the boiler set for a high (80C) flow temperature. This arrangement isn’t great for a boiler as it may be above the temperature where condensing can take place, but it’s very bad for a heat pump system. Big radiators also (IMO) create a more pleasant heat in a room. Anyway, good luck with your building work and heating solution!

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