UKC

my variable rate tariffs with Eon-Next is (p/kWh - p/day):

Elec: 27.36 - 48.53      Gas: 7.28 - 27.22

Gas has a hell of a lot to rise before it gets to elec prices.     And then there's the efficiencies of the the heating appliance to factor before even adding cap ex for swapping.

Unless I'm missing something, the green drive to switch to all elec seems like a dystopian horror show for the wallet - even if you can afford cap ex for air-source c/w suitably insulated home, etc, etc.

In reply to Rogsax: You are not missing something. Even with a very efficient heat pump the electricity will cost you a lot more than gas would for an efficient condensing boiler. Heat pumps can be great for a building that is designed with them in mind; very good insulation, underfloor heating etc. For retrofit most houses will not be adequately insulated and the radiators unsuitable for the lower water temperature. Furthermore when it gets very cold outside (sub zero) heat pumps lose a lot of their capacity, in many cases this is compensated for by direct electric heating.

The government’s focus on heat pumps in isolation is misguided and pointless without a much more expensive programme to improve insulation of the UK’s housing stock; the worst in Europe. The government decided not to require higher insulation standards for houses under lobbying from the big building companies. I’ve experienced this lobbying around 20years ago when I was an energy consultant supporting Scottish Executive, thicker insulation reduces the number of houses you  can fit on a plot! And as for mandatory pressure testing to ensure houses are built properly; forget it!

As for green electricity, when you switch your heat pump on it won’t cause a dormant wind turbine to spin up, rather a gas fired power station will increase output. This marginal emission factor for grid electricity will be more significant than the average emission factor until the UK has a much greater proportion of zero carbon electricity generation, eg a lot more wind plus new nuclear.

In reply to kevin stephens:

Yes but...

The efficiency of a new ASHP is approaching 400%.  A pessimistic 350% means that the effective cost of a unit of electricity will be 27.36/3.5 = 7.8p.  Which is pretty comparable to the 7.3p that the OP is paying.

On top of that, there are tariffs with much cheaper unit rates, especially time-of-use ones.  My heat pump does most of its work at 5p/kWh on an EV charging tariff.

And if the OP is ditching gas altogether then they're also saving 27p/day in standing charge.

True but fixable.

An absolute disaster, agreed.

Agreed, most of the time.  But if you're getting 350% efficiency at the heat pump then it's rather less CO2 overall.  And as our grid decarbonises, so will heat pumps.

Don't get me wrong, heat pumps can be disasters in the wrong house, but in the right house they're almost a no brainer.

In reply to Jamie Wakeham: the nameplate efficiency of some heat pumps may be 400% but the Seasonal efficiency in the UK will be a lot less at around 300% or less due to reduced performance during very cold weather when they have the most work to do 

In reply to Jamie Wakeham:

That's all very well. Can you give me the £10,000 plus for insulation, bigger radiators and the the cost of the unit itself?

If so, I'm all in!

In reply to kevin stephens:

I guess that depends on the part of the U.K. we're talking about, much of the U.K. is pretty mild in the grand scheme of things.

In reply to Rogsax:

The current price cap has electricity at roughly 3x the price of gas, even air sourced pumps approach 300%. Yes their prices have to fall but they will, they're heavy duty fridges, not magic. It's quite a stretch to call the shift off gas dystopian IMHO.

As for insulation, it's not the problem with heat pumps (it's an additional opportunity), the price barrier to low temp wet central heating in a lot of cases is shit microbore pipe which can't flow enough. New radiators (convectors) are cheap, re-piping isn't. 

Re. The insulation point, my gas boiler is 25kW, a 300% heat pump of 8kW (a totally reasonable electrical load) would replace it (ish!). Better insulation isn't needed, it's just a boody good investment. 

Jk

In reply to Rogsax:

We run an all electric house, previous was a gas ch heated with a combi boiler. The houses are identical as we were renting two doors up the road from our current place.

Not seen any great change in bills despite the current place having storage heaters and a wood burner.

Both are 60's houses with added insulation.

But in my efforts to go off grid I've been looking at air to air ashp and a wind turbine.

Seems the air to air is a lot cheaper to install (depending on your house) and means no radiators taking wall space.

Also makes more sense to me to heat the air directly, rather than add another inefficiency of heating water to heat the air. 

In reply to Rogsax:

The correct answer is actually insulation.  If you reach a specification similar to Passivhaus, you need only a tiny heat input, and so electric radiant is fine, no complexity needed.

Hard to do for older properties (and will need relaxation of listed building/conservation area rules to allow e.g. draughty old sashes to be replaced), but a standard like Passivhaus should be mandatory for all new build immediately.

In reply to artif:

Water will already be used to transmit the heat from the device to the house.

In reply to Maggot:

Well, no.  If you'd installed it before Thursday then the RHI would have paid you handsomely; the new incentive is less generous but there's still a £5000 up front payment.  Beyond that I'm afraid you're on your own.

In reply to Kevin:

Our SCoP is 3.88 for heating and 3.42 for DHW.  Making measurements now to see how it's doing in real life.

In reply to jkarran:

Do you mean an input power of 8kW?  You won't need anything near that big.  Your gas boiler produces 25kW instantaneously but probably only runs for a few hours even on the coldest of days.  A heat pump trickles all day long; a max output of 8kW (so an input in the region of 2.5kW) will be appropriate.

In reply to jkarran:

I'm surprised at the number of fully renovated houses I've seen that still have that crap in.

My house was plumbed with 8mm copper microbore. I was lucky in a way, it leaked 5 times in the first 6 months of me moving in, so since I was taking floors up, it got all ripped out and replaced with single runs of 15mm plastic, point to point from a central manifold to each radiator.

In reply to jkarran:

If my house had Insulation to the standard required for efficient heat pump use I'd only have to put the boiler on for a few minutes morning and afternoon and it would be toasty warm. Yes I'd still be using gas but I'd be burning tiny amounts of it and saving a fortune on a heat pump installation and not having a big humming box in the garden. Many people don't even have a garden to put one in and most people have neighbours that will have to endure the noise.

The issue with radiators is not only the age and inefficiency of old radiators but the size you'd need to fit. Modern houses are tiny blocking off 2 meters of wall space with a big radiator is a pain in the arse.

Regarding your 25 kW boiler. Unless you live in a massive house with a massive boiler, it's probably split ~11 kW central heating and 14kW hot water. Many people only fit excessively large boilers because they fear the hot water output won't be adequate for showering.

In reply to gethin_allen:

You can get much more fin dense 'radiators' to massively increase their performance on the same wall space. My wife's boss just had her 90's at a guess house converted to heat pump, it's toasty warm working like normal central heating, the rads are maybe an inch thicker 3 layer jobs full of fins but no wider and the pump is barely audible. 

As for the hum of fans. They'll get quieter or we'll get used to it, like we have every other useful technology that isn't totally cost free (written sitting next to an annoying whirring clicking washer doing work I'd utterly despise).

Jk

In reply to Jamie Wakeham:

Yeah I meant input power and was considering like for like replacement into a house you can't pump up slowly all day because it's leaky. Obviously there are better ways to do it (adding insulation and storage) but even the crap way, using it like a gas boiler for on demand heat it's broadly cost comparable to run at current prices and the capital cost will fall over time, at least for those houses with the plumbing to support better 'radiators' .

Jk

I've never used my electric shower due to running cost. The bath and other shower are fed from a gas combi.  Can heatpumps provide hot water, or does it increase to full electric price ?

In reply to Neil Williams:

This. I live in a Passivhaus standard apartment with community heating (all electric) and have not turned on the apartment heating all winter (it's set to 20) . In Scandinavia. Insulation is king.

To clarify: community heating in this context means that the boiler (I assume) is shared by the whole block, rather than a boiler per unit. Not that the block itself is heated independently of the units themselves.

In reply to Rogsax:

There seems to be a rather one-dimensional way of looking at your choices in this thread. If money spent alone is your motivation then I can see why arguments for heat pumps and electricity are floundering.

But I'd encourage you to think in environmental and future-proofing terms too. If you can afford to pay the extra for a greener solution then I would suggest that you have a moral obligation to do so. Industry and governments can only work so quickly to transition to a carbon-neutral economy and every action you or I or anyone else on UKC makes which aids that transition is a positive action. Nobody is perfect and I totally accept that there are houses where greener solutions are just unreasonable but if you have the option and you have the money available, I would encourage you to think about the environment and go for the greener option (even if this option will only become properly greener a few years into the future when the renewable power sources have been further built out).

In reply to David Riley:

They can but you need to get a big insulated tank. You probably need an immersion heater with it to boost it to higher temperatures and make up for heavy use.

In reply to David Riley:

On the back of my fag packet: 8.5kW x 5/60 hours x 25p/kWh = 18p per shower.  Your actual numbers may vary, of course.  Gas is always likely to be cheaper than resistive electrical heat. 

Yes, absolutely.  Mine drives water up to 50C at a SCoP of 3.4.  What they cannot do is provide instantaneous hot water (like a combi boiler) - you will need a cylinder.

In reply to gethin_allen:

Thanks both.

There was a South Park episode about it

In reply to Rogsax:

Unlike electricity, Gas cannot be generated and resold by domestic users. With a combination of solar PV systems, battery storage and smart tariffs it's possible to spend far below the average on energy over the course of a year.

The problem is the upfront capital cost for these systems, but with electricity prices the way they are, it may become more appealing. Why every new build doesn't have a solar PV system and a 10kw battery is beyond me - it seems like such a no brainer.

In reply to planetmarshall:

it's all down to the pedalled myth that being green is expensive, so they fit second bathrooms, kitchen islands, garages that are too small, conservatories that are either too cold or too hot.. then complain when their energy bills rocket.

In reply to Jamie Wakeham:

The exact repayment terms of the RHI vary but l think most people will be better off under the new scheme - assuming you can get it as the total amount of money available is somewhat less. Aside from the general principle that for someone purchasing a heat pump £5K now is more useful than £7-10K in 7 years; £5K at, say, 5% per year, would be worth ~£7K anyway.

In reply to planetmarshall:

For our install, RHI is £1201 per year for seven years, and it's indexed against CPI.  Assuming CPI sits at 3.5% it's almost £9500 over seven years.  I'd rather have that than £5k in my hand now.

In reply to Jamie Wakeham:

...although I have the luxury of having been able to save enough to pay the capital cost outright.  I appreciate that if you haven't been able to do that then the £5k up front may well be more attractive.

In reply to Jamie Wakeham:

Are you storing your water at 50C or does the cylinder have an immersion heater to boost it?

Storing at 50C could mean that the colder parts of your cylinder have ideal conditions for breeding bacteria. Having a destratification pump on your cylinder will help but storing at 60C is best practice.

In reply to Jimbo C:

The thermal store is full of glycol / water which circulates around the heat pump and the rads.  DHW comes from a heat exchanger near the top.

You're right - if this was a cylinder (as opposed to store) arrangement then we'd need legionnaire protection.  I should have been more precise with the language! 

In reply to Jamie Wakeham:

Ah ha. All good