Posted by: @kev-m

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Are you sure you're getting a SCOP of 3.5?

No, it was just a sort of global in the middle figure, a general case, for a general case estimate. I suspect mine is less. The trailing three hour moving average COP for my heat pump over the last week few days, since I had the HA monitoring up and running, looks like this:

I think it is reasonably credible, eg the COP does down as the ambient goes down, but I still am not sure what the spikes are (data displacement perhaps, occasional kWhs ending up in the wrong time frame perhaps?) and if you smooth the line in your mind's eye, it looks like in milder weather I get a COP of around 3.5 to 4.0, while in colder weather it drops down to nearer 2.5. What the long term average/SCOP will turn out to be means waiting for a much longer period of data collection, although I should be able to get some of it manually from the app's historical records, just not so accessible or neatly presented without pulling it all into a spreadsheet.

I haven't been able to pull flow temp into HA yet, but it is visible on the wired controller, and in cold weather it regularly runs in the upper 40s/lower 50s, and I agree, at those flow temps, the COP is not going to be very heart warming.

If my real SCOP is less than 3.5, then oil will progressive become the cheaper fuel.

Posted by: @cathoderay

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Either I am being very thick, or something is seriously wrong with the numbers.   

Any thoughts anyone? How can an oil generated kWh be three times better than and ASBO ASHP generated kWh? Isn't a kWh always just a kWh, however it is generated? Isn't this the turkey in the living room?  

Posted by: @cathoderay

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Posted by: @scrchngwsl

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investing in solar panels and battery storage

We need to compare like with like, if ASHPs have little helpers in the background, of course they will appear cheaper, even when they might not be. That doesn't mean your total setup isn't a no brainer, it's just having the other stuff makes it less straightforward to tease out how the heat pump is doing.

 

I agree, which is why I said that it would have been at parity with gas even if only 1 of those things were true. For the avoidance of doubt, I don't need the solar panels or battery storage in order for my ASHP to be cheaper this winter than the old gas boiler. I just need a COP greater than 2.1 or so, which I have been getting even in the absolute worst weather this winter.

Indeed it is! Which brings us full circle to the unit cost of electricity. While it is artificially pegged at 34p/kWh it is bad enough. If the trailed leaks of an increase in April to 46p/kWh to test the public reaction go ahead it brings operating at the lower end of the COP range around 2.5 in the colder weather into unaffordable territory for some. 

The cost divergence from fossil fuels if you are off mains grid is now a real issue. It is not helped by there being no bulk LPG deliveries in Scotland between January and April this year as Shell who run the gas plant at Mossmorran have flogged all their LPG output to Europe to get the higher prices.

FWIW, I have just calculated my global (heating and DHW combined) COP from 25th Nov 2022 (when I started collecting sufficient data) to the beginning of this week, and it is 3.07.

Doing these calculation can only aggravate my HPDHD (Heat Pump Deficit Hyperactivity Disorder).  

Posted by: @abernyte

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The cost divergence [of electricity] from fossil fuels if you are off mains grid is now a real issue.

I agree, and you were right to bring this up, along with the geographical lottery of supplies. Not only will it create a lot of real personal hardship for those who have committed to AHSPs, it will also hinder further ASHP installations, as folks look at the likely future running costs, and say no way. Truly, what the government encourages with one hand, it takes away with the other.

Perhaps we will see some change... 

https://www.gov.uk/government/news/making-government-deliver-for-the-british-people

"A new Department for Energy Security and Net Zero, has been tasked with securing our long-term energy supply, bringing down bills and halving inflation. The move recognises the significant impact rising prices have had on households across the country as a result of Putin’s illegal war in Ukraine, and the need to secure more energy from domestic nuclear and renewable sources as we seize the opportunities of net zero."

Posted by: @cathoderay

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Posted by: @abernyte

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The cost divergence [of electricity] from fossil fuels if you are off mains grid is now a real issue.

I agree, and you were right to bring this up, along with the geographical lottery of supplies. Not only will it create a lot of real personal hardship for those who have committed to AHSPs, it will also hinder further ASHP installations, as folks look at the likely future running costs, and say no way. Truly, what the government encourages with one hand, it takes away with the other.

Conversely, I wonder how many people are looking at their now 5 times higher, capped, gas bills, and thinking I wish I had changed to a heat pump when the 'bribe', sorry grant, was up to £10k.

Of course higher electricity prices make it more unattractive, but the premise of question assumes that electricity becomes more expensive than alternative fuels. It's current cost is already artificially high as it is contractually tied to higher gas wholesale prices, which is the source of 40% of electricity generation, whilst renewables now provide 30% and have decreasing wholesale prices yet no direct effect on the price of electricity! Surely that will have to change after the past couple of years.

There are pros and cons to having a heat pump as a heating source. Financial advantage is not in the pros list, as even if you calculate the relative cost of energy supply to be in ASHPs' favour today none of those costs are fixed and likely will continue to change and rebalance. But a running-cost saving of a couple of hundred pounds a year either way is neither here nor there given the large amount required in installation costs. And I don't think anyone goes into this really knowing what the additional lifetime costs of keeping an ASHP going will turn out to be.

But in opposition to the effect of gov grants sucking people into investing into the technology (sometimes without enough due consideration of all relevant factors) it is certainly true that should electricity prices rise relative to other fuel sources then that will appear on peoples cons list and become a dis-incentive to choose the technology. But the other fuel sources – gas, oil, wood, biomass – have major environmental consequences, and unfortunately most people, for most of their decisions, do not choose to factor in these considerations unless they can do so at minor inconvenience to themselves. My green halo isn't that visible.

I think the biggest handicap to ASHPs without market-bending grants is their complexity of operation combined with a lack of clear explanation on using them – the pool of people willing to invest time on them for the sake of green principles and in engage in forums like this is not that large, surely. We've got a govt campaign right now telling people how to set their simple gas boilers to run more efficiently – because plumbers set them up to be wasteful and more expensive to run and the end user remains ignorant!!

There seem to be several different topics floating about here, all interrelated but nonetheless separate.

Firstly, why should the electricity price be linked to the cost of fossil fuels? It's a hot topic and easy to understand why there would be a link if all electricity was generated by consuming fossil fuels but now so much renewable energy is being produced it seems a lot more difficult to justify such a link - or at least such a linear link (bearing in mind the seasonality of renewable energy production). Whatever one's viewpoint, it has at least become contentious enough for politicians to deem it a vote winner or loser and therefore advisable for them to at least be seen to be doing something about it. When in doubt, set up a committee to review it.

Secondly, given the current price differential, is a heat pump justifiable economically? With the big caveat that it's installed correctly (another huge discussion), the answer seems to be a categorical yes.

Thirdly, installation costs. Given a typical air source heat pump installation is probably about three to four times the cost of replacing a fossil fuel boiler with a new one (I'm assuming work needing to be done to update/upgrade pipework and install latest monitoring/controlling technology on both sides), it's easy to understand the importance of subsidy schemes of one form or another. Unfortunately the BUS scheme of about £5,000 up front is a markedly less generous scheme than the RHI for anyone who can afford to pay up front and claim back later (i.e. those not necessarily the most in need of support). Basically, this all means that anyone considering an ASHP is looking at circa £6k outlay rather than circa £3k, and that's a lot of economy to have to claw back to make financial sense.

Fourthly, another point on running costs. Earlier in this thread I mentioned that my ASHP has us markedly better off than if we were still on oil. However, almost all of that operating cost has landed in about 3 months of the year. it's not unreasonable to expect cold months to be more expensive, but it's much more difficult to budget for several months of no cost followed by 3 of huge cost as opposed to twelve months of fairly stead outgoings. Even then it's certainly doable until, that is, another round of price rises kick the months of saving and careful budgeting into a cocked hat. The problem here, of course, is predictability and that is perhaps the most important issue for the Government to have to deal with right now.

Fifthly, cost calculation. We are all well aware the use of fossil fuels is far worse for the environment than that of renewable energy. However, all calculations people are doing on the viability of heat pumps centre around just the financial cost. Somehow it still seems to be in the popular psyche that if the financial cost of installing a heat pump and/or insulating a house outweighs the cost of operating a gas or oil boiler then it's justified to just burn more gas or oil to compensate. I'm well aware of the green levies currently in operation, but they are something of a drop in the ocean and apart from them there is nothing tangible to either penalise excess fossil fuel use or make green energy use more attractive. In order to level the playing field, there really needs to be some mechanism for ensuring heating system choices are based on both financial cost AND wider impact. Of course, there also needs to be significant help to those on the dirty end of the equation whilst moving over to such a new mechanism otherwise those with little choice of where they live may well end up stuck with a bill they could never have envisaged before.

Sixthly is about combinations of systems. In particular here, one of the major benefits of a heat pump is not so much its efficiency as much as the fact it consumes a type of energy that can be produced at home. If the HERU ever gets to production, it would obviously tackle the same issue for gas devices, but ultimately it's a simple logical progression. If you can produce energy in the form your heating system can use then you can run it for longer before hitting a point where you need to buy energy. The only heating systems capable of doing that are ones that run on electricity, ergo any electrical heating system combined with any domestic electrical generation will give a significant benefit over only installing one or the other.

Seventhly, fitness for purpose. It is patently obvious that heat pumps - air source and ground source - are in themselves effective, reliable and in fact really simple technology. However many threads on this forum attest to the fact few installers can legitimately call themselves professional, and that there are an unacceptable number of inappropriate installations. This means either higher running costs or remedial work that has to be done. Either way, we're staring down the barrel of a hidden cost for many. Mass adoption of an expensive investment like a heat pump is not going to happen if that expense is seen as a gamble.

I've tried to state the many topics fairly objectively and hopefully avoided giving too much of my opinion in amongst them; the topics are valid discussion points irrespective of where I stand on any of them.

Posted by: @derek-m

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Conversely, I wonder how many people are looking at their now 5 times higher, capped, gas bills, and thinking I wish I had changed to a heat pump when the 'bribe', sorry grant, was up to £10k.

Very true.

There is another indirect benefit to fitting heat pumps: it focuses the mind more sharply on heat loss reduction. With oil, I tolerated an old leaky building more easily than I should have done, the boiler had more than enough to keep up with the losses. A heat pump, especially one that is marginal or inadequate in cold weather, like mine, really does provide an incentive to improve insulation and reduce leaks. The rise in energy price on its own would I am sure also have had an effect, but putting in a heat pump underlines the importance of minimising losses even more.

@majordennisbloodnok Really great summary, nice one.

For my part, and at the risk of sounding preachy, I don't ask myself "what's going to make the most financial sense?" and then simply do the thing that generates the highest NPV -- I'm not a management consultant! I ask "what's the right thing to do?", and then try to figure out how to make that work financially.

For me, at the time, that meant getting an ASHP, but also getting solar panels, battery storage, and an EV. If I did all of those things, and invested a bunch of money, then they would all work financially. If I were to do the same calculation now, the ASHP would stand on its own without the other stuff, but back in early 2021 when my wife and I moved into our "forever home" and I was planning this stuff, I needed the other stuff as well. Either way, the investment has returned way more than I expected, but I would have done it anyway and was content with a lower ROI than simply replacing my old gas boiler with a new condensing boiler, my old petrol car with a new petrol car, etc.

Posted by: @jeff

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Perhaps we will see some change... 

https://www.gov.uk/government/news/making-government-deliver-for-the-british-people

"A new Department for Energy Security and Net Zero, has been tasked with securing our long-term energy supply, bringing down bills and halving inflation. The move recognises the significant impact rising prices have had on households across the country as a result of Putin’s illegal war in Ukraine, and the need to secure more energy from domestic nuclear and renewable sources as we seize the opportunities of net zero."

As usual the words sound quite good, and are in the correct order, but I suspect they will have the same set of idiots try to put the words into practice, with the usual disastrous results.