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My four-bed house currently has traditional heating system with a combi boiler. I am looking at ways of lowering bills due to my gas usage being well over £300 a month already and its only November!

I wanted to know if now is the time to invest in an electric boiler or replace all the radiators with electric radiators (would have to get them all hard wired in). I know the initial costs will be a lot, but in the long run will it be cheaper than the gas boiler, as I assume the electric boiler/radiators are far more energy efficient?

Does anyone have any experience with how expensive electric boilers are, in the current economic climate in the UK? Also, if electric boilers are no good, is it worth shelling out on electric radiators being hard wired in each room?

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    In North America electric heating seems to be the most expensive for running costs. If wanting to go with electric the recommendation is to use heat pumps. Would need to know your electric cost compared to cost of gas.
    – crip659
    Dec 5, 2022 at 13:56
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    If you're swapping from gas to electric heat, use a Heat pump. (aka mini-split aka reverse cycle air conditioner) 3 or more times the heat for the same electricity input.
    – Ecnerwal
    Dec 5, 2022 at 14:11
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    Unless I'm misunderstanding "electric radiators" (which I take to mean that electricity is used to create heat which then radiates into the room), you may as well plan on buying 50 toasters and plugging them into outlets and turning them on. That is what an "electric radiator" is - resistive wire is heated by electricity flowing through it. It is very inefficient to run, though it's really cheap to buy. You could invest in incandescent light bulbs - they do essentially the same thing, but produce light in the process, too.
    – FreeMan
    Dec 5, 2022 at 14:44
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    It might be worth looking into the house insulation/sealing. Sometimes the biggest bang for buck/pound is upgrading the insulation to keep the heat in, instead of heating the outside.
    – crip659
    Dec 5, 2022 at 15:54
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    Right on @crip659 - that is almost always the best (adjusts idiom on the fly) profit for the pound.
    – Ecnerwal
    Dec 5, 2022 at 16:15

2 Answers 2

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(I've assumed you're in the UK, as you've priced in pounds)

Given the price difference in the UK between mains Gas (currently about £0.10/kWh for domestic use) and Electricity (currently about £0.33/kWh for domestic use) is always about a factor 3, and that is unlikely to change until our energy grid fundamentally shifts away from Gas powered generation and market based on marginal pricing, Gas heating is more cost efficient than almost all forms of electrical heating.

That said the efficiency gains of a heat pump set up (amplifying heat input by about 4), can make that more efficient. As then you could get 4 kWh of heat for 33p. However air source heat pumps in the UK are rubbish in the winter as the outside air is too cold, and the efficiency drops. So you need even more expensive ground sourced heat pumps.

The only other mitigation would be if your electricity is unusually cheap - such as local generation (Solar) or a time based tariff. But neither are in my opinion good enough incentives (financially) yet. However if you interested in mitigating carbon emissions (instead of cost) then Electric heating can still make sense (depending on generation source).

Update to add - as @Ecnerwal points out in the comments there do exist air source heat pumps that can be efficient at lower outside temperatures. If you consider air source heat pumps check their capability matches your requirement.

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    If you can get them (presumably depends what's imported), air source heat pumps are made that would consider the British climate trivial to operate efficiently in. My Mitsubishis go to -15°F / -26°C
    – Ecnerwal
    Dec 5, 2022 at 14:36
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    @Ecnerwal awesome - they sound like solid units, can they cope with high humidity? My experience of heat pumps here in the UK is that on days when the temperature gets no higher than a few °C above zero (January & early Feb) they ice up as it's often relatively humid in the winter here... and stop working efficiently. They then start behaving as simple resistive heaters ... as they go into "de-ice" mode heat up the outside electrically to melt the ice, then pump that heat (whats left of it) back inside.
    – MNB
    Dec 5, 2022 at 16:17
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    There are older (& brand-new) units not suitable for below 0°C that are useless like that. There are plenty of people who still think that's the only kind there is. Cold-climate air-air heat pumps have a defrost function. During heating season the system briefly goes to cooling mode to melt the frost, some with and some without an additional resistive heater to speed that process, then it returns to heating. Mine have that heater (outside only) but no "resistive backup heat" inside - they don't need it. The outside heat is really just for ice melting.
    – Ecnerwal
    Dec 5, 2022 at 16:37
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    The net heat collected is still far more than is spent on melting the ice, but it's certainly more efficient when the condensate just drips off and you get the benefit of the latent heat from condensing it without having to pay back heat to melt it off as Ice. Inclusive of the melting, the efficiency remains above 300% far below 0°C (on my particular units, anyway.)
    – Ecnerwal
    Dec 5, 2022 at 16:45
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I think you have something turned around in your thinking.

Electric (resistor element based heating) is comically inexpensive to buy the elements (baseboards, radiators etc.) However then they are brutally punishing to actually operate. For instance this "radiator" (electric heater actually) costs only 80 quid to buy, but then costs 2 quid to run it for 3 hours!

So if you are facing nightmare heating bills, you'd be "out of the frying pan and into the fire" switching from methane to electric.

What you really are thinking of - costly to install but cheap to run - is heat pumps. But get in line - they've suddenly become very popular in Europe.

Technology Connections covers these in depth in a lovely series, and this video addresses the "does this really use less gas than burning it locally" question - relevant to climate change and perhaps other reasons you might care about using less gas. The answer is "yes", since 2.5 COP is the efficiency needed for the environmental win and 3.3 COP is that needed for the cost win based on MNB's numbers. Better heat pumps can beat that by a wide margin.

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But heed this video's words carefully - there are 3 things you should put even ahead of a heat pump: Those are insulate, insulate and insulate.

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