Electric boiler?

JohnW2 · 2026-01-29T15:38:59+0000

Hi folks,

A few weeks ago I had a conversation with a friend, and I was reminded about it by a full-page newspaper advert yesterday.

Rather like me, my friend has an ancient gas boiler providing CH and DHW which he wants to 'upgrade/update'. He has spoken to a number of 'heating engineers' who have (I think all) suggested that installing a heat pump in his home would not be practical. Most of them therefore talked to him about the various options for a modern gas-fired system.

However, what he wanted to talk to me about was one of the engineers who had 'recommended' an all-electric approach, using Fischer products - either an electric combi or an electric heating-only boiler plus an electric instantaneous water heater. Yesterday's advert mentioned those two possibilities and listed all sorts of 'advantages' of this electric approach, but said nothing about downsides and, in particular, said nothing about running costs. The material on Fischer's website is much the same.

He asked for my advice, and I said that, purely on the basis of the relative prices of different fuels, it sounded like a pretty crazy idea to me!

Thoughts? So long as gas (or LPG, or oil) remains available,and assuming no massive changes in relative fuel prices, is there ever a situation in which it would make sense to even consider an all-electric approach to space/water heating?

Kind Regards, John

Murdochcat · 2026-01-29T16:41:20+0000

Replace the gas boiler with another gas boiler. Nothing else, at the moment, makes ANY sense

Why Not Indeed · 2026-01-29T16:50:52+0000

JohnW2 said:
I said that, purely on the basis of the relative prices of different fuels, it sounded like a pretty crazy idea to me!

For me today, gas is 5.89p/kWhr and electricity averages 24.68p/kWhr. Back of the envelope, you would need an ASHP install with a COP of about 3.6 to match the fuel costs of an 85% efficient gas combi boiler. That's not obviously crazy, and this is the most expensive time of the year for electricity as well.

Harry Bloomfield · 2026-01-29T16:53:45+0000

JohnW2 said:
However, what he wanted to talk to me about was one of the engineers who had 'recommended' an all-electric approach, using Fischer products - either an electric combi or an electric heating-only boiler plus an electric instantaneous water heater. Yesterday's advert mentioned those two possibilities and listed all sorts of 'advantages' of this electric approach, but said nothing about downsides and, in particular, said nothing about running costs. The material on Fischer's website is much the same.

He asked for my advice, and I said that, purely on the basis of the relative prices of different fuels, it sounded like a pretty crazy idea to me!

'A solution', if you have no gas, or other solution, but for everyone else.....

JohnW2 · 2026-01-29T17:00:32+0000

Murdochcat said:
Replace the gas boiler with another gas boiler. Nothing else, at the moment, makes ANY sense

As I wrote, that is my view, and the advice I offered.

JohnW2 · 2026-01-29T17:02:54+0000

Why Not Indeed said:
For me today, gas is 5.89p/kWhr and electricity averages 24.68p/kWhr. Back of the envelope, you would need an ASHP install with a COP of about 3.6 to match the fuel costs of an 85% efficient gas combi boiler. That's not obviously crazy, ...

That is certainly my view.

Why Not Indeed said:
and this is the most expensive time of the year for electricity as well.

I'm not sure I understand that - it implies that the cost opf electricity goes down at other times of year (Summer?) - which is not something I've ever seen happening. Have I perhaps misunderstood you?

JohnW2 · 2026-01-29T17:04:19+0000

Harry Bloomfield said:
'A solution', if you have no gas, or other solution, but for everyone else.....

Quite - that's why I wrote ...

JohnW2 said:
..... So long as gas (or LPG, or oil) remains available,and assuming no massive changes in relative fuel prices, is there ever a situation in which it would make sense to even consider an all-electric approach to space/water heating?

Why Not Indeed · 2026-01-29T17:12:07+0000

JohnW2 said:
implies that the cost opf electricity goes down at other times of year (Summer?) - which is not something I've ever seen happening. Have I perhaps misunderstood you?

You do not misunderstand. I am on a variable-rate tariff. The point I am getting at is that if you can break-even with a reasonable COP at an expensive time of year then you could conceivably come out ahead across the year.

Harry Bloomfield · 2026-01-29T17:15:09+0000

JohnW2 said:
I'm not sure I understand that - it implies that the cost opf electricity goes down at other times of year (Summer?) - which is not something I've ever seen happening. Have I perhaps misunderstood you?

My own cost varies, with each day, dependent on demand, wind, and solar.

Murdochcat · 2026-01-29T17:19:19+0000

JohnW2 said:
As I wrote, that is my view, and the advice I offered.

I was merely agreeing with you

No doubt someone will be along to disagree

ericmark · 2026-01-29T17:46:49+0000

JohnW2 said:
He asked for my advice, and I said that, purely on the basis of the relative prices of different fuels, it sounded like a pretty crazy idea to me!

Yes, I would agree. But I would say CH and DHW are two completely different things. CH yes gas or oil, as any attempt to store and release latter seems to have problems.

But DHW I tend to use maybe a pint at a time, and I know from caravan days these things

work well, I looked at the price £60 - £150 and thought not worth it for me. But the central tank is in summer using solar and off-peak, due to losses boiler to central tank loosing that much energy.

JohnW2 · 2026-01-29T18:06:54+0000

Why Not Indeed said:
You do not misunderstand. I am on a variable-rate tariff. The point I am getting at is that if you can break-even with a reasonable COP at an expensive time of year then you could conceivably come out ahead across the year.

Fair enough - but he presumably expects that he will have whatever system he decides upon (presumably/hopefully not electricity!) for many years, so it is the long-term cost (cost over whole years) that matters - which is why I felt the fact that "this is the most expensive time of the year for electricity" to be irrelevant.

JohnW2 · 2026-01-29T18:08:00+0000

Harry Bloomfield said:
My own cost varies, with each day, dependent on demand, wind, and solar.

Indeed, but as I've just written, it's a long-term situations, so that the fact that "this is the most expensive time of the year for electricity" is seemingly irrelevant.

JohnW2 · 2026-01-29T18:09:25+0000

Murdochcat said:
I was merely agreeing with you

I realise that, and was acknowledging it.

Murdochcat said:
No doubt someone will be along to disagree

I suppose that anything is possible, but on this occasion I find it hard to believe that any sane person would disagree with me!

JohnW2 · 2026-01-29T18:13:27+0000

ericmark said:
Yes, I would agree. But I would say CH and DHW are two completely different things. CH yes gas or oil, as any attempt to store and release latter seems to have problems.

Glad you agree, but having 'instantaneous' hot water heating does not have to be electric - gas (and I imagine probably also oil) combis and standalone instant water heaters clearly do exist - so we are then presumably simply back to the relative cost of the fuesl?

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