Posted by: @cathoderay

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At the risk of sounding like a stuck record, this is is so important, that it bears repeating.

In raw terms, heat pumps are about three times more efficient (or more) than gas boilers, which is why this heat pump propaganda/marketing bullshit is allowed, but it only translates into costing three times less to run if you ran your gas boiler exactly as you run your heat pump ie on all day, which of course most people don't.

Over a set 24hr period the kWh INPUT must equal the kWh LOST regardless.  Of course if you run your gas boiler to only heat the rooms of the house you are in at the times you are in it, then that is not how heat pumps are designed to run and it would be a meaningless comparison to try and compare these two scenarios.

Most people I know, run their boilers targeting a set temperature for a big chunk of the day, in this case the boiler has to play a massive catch up at the beginning of the "on period", and a modulating boiler should get close to the operating mode of a heat pump (with the main difference in the flow temp and emitter sizes) once it has caught up.

This is, of course, complex stuff, and it would be interesting to model and prove the differences (if any) programmatically, rather than guessing they are the same.  This may be possible with SymPi, I am not sure, but someone out there must know of modelling software that could be run against a simple "box house" model to see what the differences maybe. 

@bontwoody and @toodles - I am not comparing apples with rabbits or bananas with boomerangs for that matter, just making a simple point that, as I have found in the real world, the statement that a heat pump is three times more efficient than a fossil fuel boiler does not translate into the implied one third of the running costs. As covered in detail in another thread, my energy in using a heat pump is about the same as the energy in I used with oil. This led to what I called 'the paradox' (why the same energy in if the heat pump is three times more efficient?) which was in due course resolved by noting that I ran the two systems very differently, oil on a timer, heat pump on all day.

As my system is marginal (max output barely matches heat loss at design temps) and given the current Midea controls, I cannot run my heat pump on a timer, ie have an overnight and/or day time setback, because the system cannot recover in a reasonable time (I've tried it, and it takes several hours).

In passing, if I were to compare apples with rabbits, my heat pump at today's electricity prices is far more expensive to run than had I remained with oil, which is currently around 60p per litre (or around 6p per kWh). 

I know very well pointing this out will be unpopular with heat pump aficionados because it tarnishes the shiny heat pump image, but the fact is, it is reality for me, and it seems many others - which is why @transparent noted that "the majority of those households ended up paying more for their energy than before, even though £4000 of fabric upgrades (insulation) was also utilised per property."

People considering a heat pump installation will surely want to know what the real costs of running a heat pump are likely to be before the installation (which they may still nonetheless go ahead with), rather than get a nasty shock after the event. 

Posted by: @amanda1

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This is a ‘renewable heating hub’. Not a ‘don’t get renewable heating’ hub.

See the above. I am not against getting a heat pump (not necessarily the same as renewable, depends on how the electricity it uses is generated), indeed I went ahead and got one despite some advice that I shouldn't (old leaky building, not suitable for a heat pump, another (wrong) stuck record, see countless posts passim). All I am suggesting is that people should get one with their eyes open, and that includes realistic real world assessments of likely running costs for their installation. It's great that you were very well informed on the potential pitfalls of ASHPs - all kudos to you - but not every one is (I for one wasn't) hence my suggestion that in a forum we include both the pros and possible cons of installing a heat pump, including any effect on total running costs associated with any changes in the way a heating system is run.

@transparent can of course speak for himself, but I think we will find that he is an enthusiastic but realistic advocate of heat pumps.

@cathoderay  (second attempt to post this as my first attempt has not appeared) This stuck record would like to suggest that it is an unfair comparison; apples and rabbits will never show any sense of accuracy. Were the kW/h. prices of the different forms of energy comparable, then heat pumps would surely be everyone’s favourite! Whilst the kW/h. price of gas or maybe even oil, is so much lower than that of electricity with the imposed levy on it, then the elephant is standing on an unlevel playing field. Bring the energy costs in line and not only would the heat pump be much cheaper to heat a dwelling than other forms, it might be done so much more cleanly. I have 8.1 kWp of solar panels and battery storage and although this will help reduce my demand on the grid in winter, I will still need a lot of grid power to run my ASHP.; I hope that my exported solar energy during the summer months will help to lessen the impact. Regards, Todles

@cathoderay  Couldn’t disagree more. I had a Stiebel Eltron WS 25 AS installed with Easytron electronic controls. Average annual efficiency has been 4.4 for past 12 months and despite higher electricity costs runs at better than 50% of oil cost.  BUT the installer was hopeless one or two issues re rooms not getting up to temperature turns out to be undersized rads. I have had to research all this - you can’t trust their membership of MCS or NICEIC to protect you either. Research and interrogate your potential installer thoroughly. Most important factors are flow temp. (The lower = most efficient), heat loss calculation by room and then heat emission from radiators based on correct DT!

Posted by: @william1066

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Posted by: @cathoderay

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At the risk of sounding like a stuck record, this is is so important, that it bears repeating.

In raw terms, heat pumps are about three times more efficient (or more) than gas boilers, which is why this heat pump propaganda/marketing bullshit is allowed, but it only translates into costing three times less to run if you ran your gas boiler exactly as you run your heat pump ie on all day, which of course most people don't.

Over a set 24hr period the kWh INPUT must equal the kWh LOST regardless.  Of course if you run your gas boiler to only heat the rooms of the house you are in at the times you are in it, then that is not how heat pumps are designed to run and it would be a meaningless comparison to try and compare these two scenarios.

Most people I know, run their boilers targeting a set temperature for a big chunk of the day, in this case the boiler has to play a massive catch up at the beginning of the "on period", and a modulating boiler should get close to the operating mode of a heat pump (with the main difference in the flow temp and emitter sizes) once it has caught up.

This is, of course, complex stuff, and it would be interesting to model and prove the differences (if any) programmatically, rather than guessing they are the same.  This may be possible with SymPi, I am not sure, but someone out there must know of modelling software that could be run against a simple "box house" model to see what the differences maybe. 

Correct (apart from "Over a set 24hr period the kWh INPUT must equal the kWh LOST regardless." which I suggest only applies in steady state conditions), we have discussed this many times. My own data, notwithstanding it's limitations eg oil usage data only available per annum, is real world observational data, which as you may recall I always prefer over modelled scenarios. It is a matter of recorded fact that I used about the same number of kWh per annum using oil as I did over the last year using a heat pump. I also have empirical data showing the heat pump struggles to recover from even small overnight setbacks, because the standard Midea controls don't allow a boost setting (unless done manually, which isn't going to happen eg I get up at 0400 to increase the LWT). Again, as previously discussed, I may be able to achieve a boost setting using python and modbus, eg if set room temp minus actual temp > 2, then new LWT = weather curve LWT plus 2, but this will have to wait until next autumn before testing it.

@cathoderay Hi, I did read the post about the "paradox" you saw with your oil/electricity comparisons and tbh I couldnt understand why it should be. Comparing my gas usage and electricity before and after I see the the same heating requirement in kWh. Energy is energy after all no matter how its generated and I took the trouble on this install to put in a heat meter and open energy monitor which gives me very accurate readings.

If your house is poorly insulated as you suggest then you would need to use a high flow temperature which may well drop your COP below 3. So far my COP as measured in the brief spring timeframe I had is well over 4. It will be interesting to see what happens next winter.

Posted by: @toodles

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Were the kW/h. prices of the different forms of energy comparable, then heat pumps would surely be everyone’s favourite!

Very possibly, but the key and only point I am trying to make is that installing a heat pump may leave you with no choice, if you want to stay reasonably comfortable, but to run the heating very differently, and this may in turn mean your expected savings do not appear. 

Posted by: @gfkw1947

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Couldn’t disagree more. I had a Stiebel Eltron WS 25 AS installed with Easytron electronic controls. Average annual efficiency has been 4.4 for past 12 months and despite higher electricity costs runs at better than 50% of oil cost.  BUT the installer was hopeless one or two issues re rooms not getting up to temperature turns out to be undersized rads. I have had to research all this - you can’t trust their membership of MCS or NICEIC to protect you either. Research and interrogate your potential installer thoroughly. Most important factors are flow temp. (The lower = most efficient), heat loss calculation by room and then heat emission from radiators based on correct DT!

"despite higher electricity costs runs at better than 50% of oil cost" - can you give actual figures (in kWh, we can then convert that to GBP depending on which apple we want to compare with which rabbit). As the oil price per kWh is currently far less than the electricity cost per kWh, in many cases, oil will currently be cheaper. 

We have discussed MCS failings, the importance of correct radiator sizing following room by room heat loss estimates (and their failings too) and the centrality of LWT to heat pump running many times, and you are absolutely right to underline their importance again. 

Posted by: @bontwoody

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Comparing my gas usage and electricity before and after I see the the same heating requirement in kWh.

There is energy in (what the heat source uses) and energy out (what the heat source delivers to the house). My 'paradox' was that the energy in was about the same for both oil and the heat pump, which didn't make any sense, given the heat pump is supposed to be several times (say 3-4 times) more efficient than the oil system: in theory, it should need 3-4 times less energy in, to get the same energy out. What actually happened was I made changes (necessary to achieve the same comfort levels) to the way I ran my heating, going from timed heating to always on heating, and as a result, my energy out did increase very substantially, which in effect wiped out the better heat pump efficiency savings. C'est la vie.

Posted by: @cathoderay

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@transparent can of course speak for himself, but I think we will find that he is an enthusiastic but realistic advocate of heat pumps.

Speaking for myself... yes!

I am sufficiently enthusiastic that I am

• developing new technology to decrease the cost of electricity required by heat-pumps
• in active discussion with politicians regarding the rules/regulations for heat-pump installations

@amanda1 - it was the Catapult report on the BEIS-funded trial which chose their strapline to use a comparison with gas boiler efficiency.
I'm commenting on how strange that seems for a number of reasons... including how inappropriate it is for those who have no gas!

Having spent 18-months communicating with many of the Trial participants, the main message I got was that the Trial outcomes were compromised by a number of factors which you would have expected BEIS to get right:

• the poor level of installation was a critical factor in low efficiency
• few installers appreciated the need to calibrate/optimise the system post-installation, leaving the manufacturers to attend on site and reconfigure the set-up. Indeed one very large installation company was dismissed from the scheme for repeatedly poor work and system design
• householders didn't receive the training and documentation required by the Building Regs
• with sufficient knowledge, most householders could achieve greatly improved efficiency (higher COP). Those in SE England shared that knowledge with each other using a (private) online forum

I am particularly interested to hear what @amanda1 has to say because she is a housing association tenant.

I am a member of a group of techies and local government employees who are about to open discussions with a housing association. We have a number of proposals to reduce the cost and amount of energy required by their tenants whose homes are fitted with Smart Meters. In my area, most such houses are not on the national gas-grid, although a few villages have private gas supplies.

There is a clear need to install heat-pumps, but only if the tenants can afford to run them.
The housing association will not entertain anything which places their tenants further into fuel poverty.

Local Councillors are actively seeking information on such strategies, which is very encouraging.
Overall, there is much to be gained by such partnerships.
I'd rather spend time working with others towards solutions, instead of protests, rallies and social disruption.

@transparent Hi - I am not a housing association tenant. I am an owner occupier. I can afford to run an ASHP even if it costs more than my storage heaters used to cost. I am not saying I WANT to pay more, but I am alert to the fact that the ASHP may cost me more.  However, I think it will cost me the same or less, even if the COP falls to 1.0 in winter. I live in a remote highland village. I did not have access to the gas grid. I did not have a gas boiler or an oil boiler. I did not run my storage heaters on a timed setting as that is not possible with old storage heaters. They had to be on all the time. They generated an internal temperature of about 16 C in winter. I am used to walking around the house in winter walking gear and I don’t expect to dry my washing over the radiators. I also have a multi fuel stove. I made the decision to apply for the grant myself, and that was on the basis of much reading around and speaking to neighbours who have had ASHPs for many years.  I had to get a different more modern heating system, I had to get away from storage heaters because they are the most expensive form of heating and the worst when it comes to EPCs, and I couldn’t afford a loan AND pay for the possible additional running costs for an ASHP given the current energy tariffs. So the grant, £16,000 worth of it, is greatly appreciated.  

If I were a Housing Association tenant my situation might be very different. Also, if I were part of a housing scheme where the ASHP settings were controlled centrally from ‘on high’ I would be deeply worried. But I am not in that situation. 

In my village there are several council houses who have had ASHPs fitted before last winter. This is anecdotal and subject to many variables but one of them has an Ecodan, the same as mine, and previously she also had electric heating. She has made a saving despite having two kids and masses of hot water consumption and electricity consumption other than the ASHP. She does have solar which helps. Another neighbour was ‘concerned’ last winter when her Heat pump consumed 20kWh a day in a cold spell….😂 I found this figure hard to believe and  my calculations of anticipated consumption are based on 60kWh a day. I intend to keep it on Auto Adaptive mode, though I might look at Weather Compensation. I don’t use much Hot Water at all, so that reduces its efficiency, but neither do I require tropical temperatures.

However, our winters here are very cold and snow lies for days, we do have power cuts occasionally, and that is part of the learning curve.

I think one of the problems here is the general expectation of a high COP. While we should all expect manufacturers to live up to their promises, though they don’t always do so, I don’t care what the COP is so long as it’s not -0.00000001. Or any negative number. My prime priority is KWh consumption not being more than previously (14,000kWh total pa, almost entirely the storage heaters). Give me the examples of ASHPs using more than that, in a small-ish bungalow on a Room temperature control set at 18 degrees day time 17 degrees O/N average daytime temperature in winter =I have been searching for them. Some people report large KWh usage in winter but everybody in these forums seems to have huge houses and have their system on timed with underfloor heating and indoors temps of 21C, and if the temperature falls below zero and there’s a flake of snow they think it’s an extreme winter. 

@transparent also, I agree that the lack of documentation and explanation is a big obstacle. In my case, I have NO paperwork whatsoever, whatsoever at all at all…. only the Ecodan and the phone number of the installers. Home Energy Scotland, one of the partners in this scheme, said that they rarely got updates from either Changeworks (who are overseeing the scheme) or from Moray Council. Changeworks seem unreachable. There is a LOT of tax payers money invested in this scheme and the different partners don’t seem to know what each if them is doing. 

But ASHPs are complex to use, never mind set up. Many of the people who will be having ASHPs fitted in council properties will be elderly or vulnerable and may struggle to comprehend any detailed explanation. Yesterday I came across this set of instructions for some Housing Association tenants in the Hebrides: these simplify things down but leave tenants with very little control. 

HEBRIDEANHOUSING.CO.UK "https://www.hebrideanhousing.co.uk/wp-content/uploads/2019/11/Mitsubishi-tenant-guide.pdf"

@cathoderay Sorry, I should have been clearer. I was talking about kWh in gas v kWh in electricity multiplied by the COP. ie if I used 24 kWh of gas previously, I am now using 6kWh of electricity (at a COP of 4). I would be very interested to know what COP you were getting from your heat pump if you are able to measure it accurately.