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Heat Pump Update.

November 22, 2020

By Paul Homewood


  As promised, back to those heat pumps!


 See the source image


Yesterday I wrongly wrote:


According to the Tradesmen Costs website, heat pumps would range from 6 KW for a terraced house to 9 KW for a typical detached.  If we take 8 KW as the norm, 25 million homes would potentially need 200 GW of grid capacity, purely for heating alone.

In fact, the energy ratings of 6 to 9 KW referred Energy Output, not input, so my figure of 200 GW is overstated.


I have therefore investigated further, and needless to say the situation is complex to say the least!


Let’s start with the Committee on Climate Change. In their Net Zero report, they concluded that peak demand would rise from 50 GW to 150 GW by 2050:



This increase included 40 GW for electric cars. Although there will be other small increases in power consumption in other areas, these tend to be offset by better energy efficiency and demand side response.

We can reasonably assume that heat pumps therefore account for about 60 GW. However, they also tell us that this assumes a large role for hydrogen via hybrid heat pumps. The hydrogen of course aims to meet peak demand in cold periods, instead of overloading the grid, but more on this later.



They also assume 19 million homes will have heat pumps fitted, whereas my calculations assumed 25 million – the CCC plan that most of the rest are part of district heat networks.

Given the above, it is not unreasonable to project we would need about 100 GW, based on full heat pumps (with no hydrogen) and 25 million homes.


But we can drill down a bit more. The CCC relied heavily on a 146 page study by Element Energy for their heating calculations.

Below is perhaps the most relevant chart, based on a large trial in Manchester:



Based on a relatively small 5 KW heat pump (typically for a terraced house or flat), the chart show the average daily half hour peak demand for three different heat pumps over a three year period. The Peak Day in the final column is the peak demand on the coldest day in those three years.

Hybrid heat pumps speak for themselves, whilst the standard heat pumps are split between those supplying hot water and those not.

My calculations assumed hot water would be supplied separately, so ignoring the hybrid option we are looking at around 2 GW of peak demand for each unit. As a typical heat pump would be 8 KW, we can increase the 2KW to 3.2 KW.

There is one other important factor here though. Element Energy’s figures are based on continuous working, which obviously reduces peak loading. It may well be that some people will not want to heat their homes at night, as it may make sleep difficult. (We have our bedroom window wide open in the middle of winter!) Equally they may not want to heat the house all day if they are out.

However, heat pumps are totally unsuited to this sort of intermittent operation, as Element explain:




Fig 9-10 shows the difference that “twice a day” operation can make to peak demand, typically increasing continuous heating by a factor of five:



Even assuming continuous operation, 19 million heat pumps would require extra capacity of 66 GW, based on the typical semi detached. Potential twice a day working would raise this figure considerable.

Hydrogen Hybrids

Which brings us back to hybrid heat pumps!

To meet winter peak loads, not to mention the demands of twice a day, an additional source of heat is vital. In the long run, the CCC propose the use of hydrogen, either in stand alone boilers, or as part of hybrid heat pump systems, where the hydrogen is piped in to boost the water temperature.

These hybrid heat pumps can cost about £1000 more.

But, of course, we have no hydrogen supply, nor are likely to before 2040. So what will we do?

There is only one answer – continue using natural gas, either through conventional boilers, or with hybrids (which would then need to be converted to hydrogen at a later date.)

In short, we can spend £6 billion a year installing air heat pumps up and down the country, but we will all still be using lots of natural gas. Given the fact that the latter is much cheaper, we may leave our heat pumps switched off all year and carry on using our boilers!




I should point out that none of the above affects my original costings, which showed that heating bills could triple with the introduction of heat pumps.

Some have queried my calculations, but they are all from reputable, expert sources. For instance, the Green Match website, set up to provide quotes and information on renewable energy sources.

The key factor is the Coefficient of Performance (COP). This measures the efficiency of a heat pump and it does this by measuring the amount of power input compared to the amount of power output produced by the considered system. Hence, the higher the value, the more efficient the system is.

The crucial determinant of COP is the outside temperature.

According to Green Match:


Given that electricity costs five times as much as natural gas, a COP of 2.8 is poor value for money.

Worse still, their costings assume good insulation and an underfloor heating system, which will both cost a lot extra to install:



One further consideration is the supply of hot water. If this comes from a stand alone electric water heater, this would be considerably dearer than that supplied by a gas combi boiler.

In a much milder climate, heat pumps might make more sense. But in Britain they are pretty useless for anybody who is on the gas grid.

  1. Alan D Tomlin permalink
    November 22, 2020 6:00 pm

    We live in south Florida during the winter (Nov to May 1), where a few households use heat pumps which work fine (almost never goes below ~35F, and even then only for a few hours in early morning), but most builders just add a resistive heater to the AC-air handling unit which is considerably less expensive than the HP. Resistive heaters are expensive to run, but we rarely use as much as about 8-10 hrs for the whole winter, and likely as not don’t turn them on at all in any given winter. Heat pumps are widely used in the more northerly sunbelt states (Carolinas to Calif); they become ever more expensive to operate and inefficient the further north one moves even in those states.

    • Harry Passfield permalink
      November 22, 2020 7:00 pm

      Love it, Alan. How much would we all like to live in South Florida. Other than in current conditions. Horses for courses.
      I’d be happy with our fracked gas and economical heating.

    • Nancy & John Hultquist permalink
      November 22, 2020 8:26 pm

      It is a big country. Washington State’s cost of electricity is lower than FL.
      9.41 vs 11.65 cents per kWh

  2. Joe Public permalink
    November 22, 2020 6:10 pm

    Running costs are affected by both number of hours-run; and, times of consumption.

    Notice the emphasis on underfloor-heating? Needed because generally heat pumps have low flow temperature AND have low output vs conventional boilers.

    Those with a conventuional boiler will find it is not unusual to see rated at maybe 22kW – 35kW. This gives it the ability to respond rapidly to changes in heat demand, and to minimise the morning and evening pre-heat period.

    For a conventional boiler, the morning pre-heat preiod will be an hour or less.

    Low-power heat pumps need 4-5 hours or more to get the building up to the desired temperature. And all that extra time the building is being heated, it’s losing heat!

    So if minimising *energy* consumption is the greenies’ main criteria, a low-power heat pump run for longer hours uses more *energy* than a swift-response conventional boiler.

    The principle is identical to the ludicrous EU proposal to limit the heat-input of a kettle, forgetting that extra heat losses occurred during the extended heating period.

    • November 23, 2020 11:18 am

      Yes, but also the energy used is directly proportional to the quantity of water being boiled. Say you have a litre of water and it takes 3 mins for a 3 kw kettle to boil this, it will take 6 mins for a 1.5 Kw to boil it.

      It does not matter whether you use a 3 Kw, a 2Kw a 1.5 Kw or a 1 Kw kettle, the same amount of total energy is required to boil 1 litre of water (save that as you suggest heat loss maybe greater the longer it takes to boil so very slightly more energy will be used when operating a lower powered kettle). The only variables are volume, start temperature and pressure (water boils at a lower temperature as pressure reduces).

      Politicians have no understanding of basic science, and that is why they are so easily led. You can see that in the Covid fiasco, which of course is so very similar to the climate fiasco, using unverified models, playing around with incomplete and dodgy data, and wild assumptions far away from reality.

      • It doesn't add up... permalink
        November 23, 2020 1:20 pm

        …and by the time you consider 500 people using kettles switching the on at random times over a half hour for their breakfast cuppa, the total load on the grid is essentially the same, because each kettle is on for twice the time, so two times as many are running at any given moment.

    • Hotscot permalink
      November 23, 2020 11:46 am

      Good assessment Jo.

      I inquired about a Ground Source Heat Pump (GSHP) for our solid masonry walled, Victorian, 3 bedroom, end of terrace cottage a couple of years ago.

      The price for the installation was well North of £20k, some getting to £30k. But to be fair to the installers, they did say there was no point as the house needed to be fully insulated with a properly installed underfloor heating system.

      Long story short; the cost for doing the whole job was between £75k – £100k, nor is it by any stretch of the imagination, a large cottage. Cosy would be the operative term.

      I must also add to that the £3,500 of new gas Combi boiler we had installed a year ago to replace our ‘inefficient’ gas boiler which was fitted, we guess, about 40 years ago. Nor was the boiler inoperative, it was the hot water tank that had perforated, and the boiler was a nuisance to do anything with because there are no spares available.

      I accept a GSHP may be a bit over the top in terms of installation costs, but Air Source Heat Pumps (ASHP) don’t come much cheaper.but the problem I see with them is the collective racket they will all make on a sprawling housing development. Particularly when individual households are making their own choices on manufacturers/installers etc.

      A few years in from initial installation will be seeing bearing failures and badly maintained ASHP’s contaminated with dirt. They will be grinding, squealing and groaning under the strain of people continually switching them on and off. It will take a generation, basically, before people accept that they are better left running all the time.

      Add to this, the problems identified by Professor Michael Kelly’s report with the physical manpower required to achieve this nationwide conversion of dwellings and commercial premises to ‘Net Zero’. Basically, we have about a third of what’s required. A big problem our government will solve by no doubt deregulating (if it’s regulated at all just now) installation standards.

      Then we’ll be left with the Cowboy industry problem we faced with 1970’s/80’s Double glazing industry, and the more recent Solar Panel installations.

      The claims for shoddy and dangerous work will be shocking, and, as usual these businesses will disappear into the night from whence they appeared. The government will be met with demand from people that they are compensated and a whole new PPI’esq industry will emerge along with associated Cowboys.

      I also notice that the latest numbers on atmospheric CO2 emissions have been released by Manua Loa, showing absolutely no indication of the 11% global reduction in man made CO2 thanks to Coronavirus. The excuse is, as ever, it’s too early for any signal to manifest itself, despite the virus being around 9 for about 9 months.

      It also occurred to me that, despite claims of being able to distinguish man made atmospheric CO2 from naturally occurring atmospheric CO2, I can’t find any CO2 monitoring stations that isolate one from the other. It should be easy, as, whilst the annual fall and rise in natural CO2 emissions is both predictable and regular, man made CO2 is not season related.

      Now, wouldn’t it make sense to plot the data separately to help the worlds population understand just how evil humanity is, or perhaps it’s just not worth revealing the truth, or perhaps it’s just not possible because human emissions are so inconsequential they can’t be recorded.

      The sooner Boris and Nut Nut are booted out of No. 10 the better.

      I also noted a Political observer comment that the time is long overdue for the senior cabinet to be independently wealthy. A sentiment I have maintained for years now, since I read that many years ago the British government was found to be so corrupt the call went up for unpaid, volunteer Businessmen to take over the running of the country.

      Corruption was eradicated and the country ran like clockwork. The time is now long overdue to resurrect the concept as, after three of the worst Conservative Prime Ministers in recorded history (Cameron, May and Boris in case you were in any doubt) and an opposition party infested with antisemitic Hamas supporters, the country is genuinely going to the dogs.

  3. Dave Ward permalink
    November 22, 2020 6:37 pm

    “The rest are part of district heat networks”

    The UEA were heavily involved in a proposed DHN in their home city of Norwich, but nothing has come of it several years later.

    “And all that extra time the building is being heated, it’s losing heat!”

    But Joe, have you forgotten that we will all have fully insulated houses by then? That’s the only possible way you could get by with such a piddling amount of heat. But I’ve also remembered that we are being advised to leave the windows open this winter to let the dreaded CV19 escape…

    • Joe Public permalink
      November 22, 2020 8:57 pm

      “The UEA were heavily involved in a proposed DHN in their home city of Norwich”

      What a fiasco that one turned out to be.

      Closer to home, UEA’s campus is heated via its own District Heating Scheme. It was oil-fired when UEA was first built, now it’s gas-fired.

      One of the great ironies is that the Climate Charlatans inhabiting UEA’s Climate Research Unit in its Tyndall Centre are forced to look out at the chimneys of the DH fossil-fuelled boilerhouse every day. YCMIU.

  4. November 22, 2020 7:00 pm

    A few years ago Highland Council, which is totally obsessed with renewables and totally ignorant, decided it would be a good idea to remove solid fuel fires from the properties of some council tenants and replace them with air source heat pumps. The result of course was that not only had the tenants lost any backup but older ladies in my village were weeping over the counter at the local post office because they could not afford their electricity bills. Similar stories about the uselessness of the Council’s bright ideas for green heating have been reported all over Highland, often that it simply didn’t work. As with so much green nonsense those who take the decisions don’t have to live with the consequences.

    • November 22, 2020 9:04 pm

      Hi Brenda. I doubt that you could find any council in the UK that is not totally ignorant when it comes to anything technological. I’ve never come across one. Ignorant councils, when coupled with ignorant governments advised by more ignoramuses, is why we are in a mess.

  5. dearieme permalink
    November 22, 2020 7:28 pm

    The only domestic heat pump I’ve seen was for a house in Christchurch, NZ. The house enjoyed a favourable microclimate, being on a quite steep north-facing slope. The garden was full of plants that wouldn’t have survived a frost.

    That is not much like Britain.

    Tell me, does anyone make a heat pump that exploits reject hot water (from showers, washing machines and so on)?

    • dearieme permalink
      November 22, 2020 7:29 pm

      Even better, buy a diesel generator for your house and apply a heat pump to the generator’s cooling water/air?

    • M E permalink
      November 23, 2020 4:46 am

      Also from Christchurch NZ
      Heat pumps are required in the new houses or rebuilt houses after the quakes, I found, when negotiating with the Insurers. They are everywhere. I don’t use the one in my rented flat ( postquake) because of it’s position on the upper wall. A down draught of warm air is not good for furniture. Radiant electric heaters I found are better in a room with double glazed sliding doors and floor length windows on two sides.

    • Ben Vorlich permalink
      November 23, 2020 11:17 am

      dearieme Wickes used to sell a system to extract the steamy air from a bathroom condense the the water vapour and return the heat to the bathroom, the water and cool air outside. It seemed like a good idea to me, remove damp from a bathroom and house and warm the bathroom at the same time. I like a warm bathroom, my East Midlands in-laws call me nesh in that respect, I say they should try bathroom where there’s a layer of ice on the toilet cistern as an alternative.

      But it just like having a large number of expensive systems in both money and energy to save the planet when in fact you’re doing the opposite, assuming CO2 is actually a problem.

      You can get this from Amazon

  6. Robert Christopher permalink
    November 22, 2020 7:38 pm

    The Great British Housing Disaster, circa 1960s, factory built housing

    It has little to do with Heating or Power Supplies, but EVERYTHING to do with an industry forcibly directed by government, which is what this government is trying to do with Greening our energy supply.

    Disaster, is an understatement, with new technologies being implemented with little prototyping, training or control, and no responsibility or penalties. Cavity Wall Insulation is already known to be a risky upgrade: what catastrophes loom ahead for the Green New World?

    How do we know that ground buried heat pumps have been installed correctly when they are part of a government effort?

    These clips give a flavour: 10:30-13:05 and 21:20-24:50

  7. jack broughton permalink
    November 22, 2020 7:50 pm

    pedants note: you have used GW for the heat pumps after fig 5.9: should be kW.

  8. John Scarffe permalink
    November 22, 2020 8:08 pm

    I wonder if anyone has calculated how much CO2 will be put into the atmosphere as a result of upgrading all our electricity networks, in the manner being envisaged? The whole idea is unnecessary and completely ridiclulous – CO2 is good for the planet. Is it certain that human activity is raising the concentration of CO2 in the atmosphere or is it natural. Extra CO2 may have a marginal effect on temperatures but look at the beneficial effect is on on the forests and agricultural outputs.

    • Dave Ward permalink
      November 23, 2020 11:32 am

      ” How much CO2 will be put into the atmosphere as a result of upgrading all our electricity networks, in the manner being envisaged?”

      Don’t worry – all the work will be carried out using electrically powered tools, vehicles, JCB’s, etc. We’ll all be treated to the delights of watching gangs of workers standing around for hours, waiting for their equipment to be recharged…

  9. Nancy & John Hultquist permalink
    November 22, 2020 8:21 pm

    Table 2.1 assumes “development of CCS”

    ” and then a miracle happens”

  10. Keith Harrison permalink
    November 22, 2020 9:43 pm

    Is there really a need to go to the expense of under floor hot water heating supplied by a heat pump? Is it not possible to have the air source heat pump simply have interior air blown across an indoor coil to warm the space? In the summer switch to cool mode for AC. In Canada where I live the Maritime provinces have little gas infrastructure and governments promote the installation of these units and folks are quite comfortable. This with winter temperatures far lower than the UK. Having a separate electric hot water tank is required but not an onerous burden. As for me my ground source heat pump keeps me warm and cool all year round in an area where max and min temperatures range from +35 to -35.C. Yes, I have a separate hot water tank. In my 28th year of operation and my resistive heater has never started. But the key is very good insulation and air tight building envelope and to set the temperature to one you need and leave it there for the season. Opening the window wide open here would be a cool to frigid experience most winter days, and that is the reason to have an air to air fresh air system paired with a heat pump to ensure humidity and stale air are removed and replaced. If such a system is impossible then the heat pumps being proposed remain a good option.

  11. 2hmp permalink
    November 22, 2020 10:25 pm

    Typical heating boilers last 15 or so. I have not heard of a heat pump lasting that long but there weren’t that many fifteen years ago. Has anyone any reliability and durability data ?

    • November 22, 2020 10:40 pm

      No data, but my gas boiler dates back to the early 1980s. Maybe not as efficient as today’s boilers but works well enough, touch wood.

      • ThinkingScientist permalink
        November 23, 2020 7:53 am

        We replaced the gas boiler in our house about 5 years ago. The one we replaced was almost certainly original from when the property was built in 1985, so the original gas boiler lasted 30 years.

        Its only fault over the last 10 – 15 years (that needed fixing/replacing every 3 – 4 years) was the safety thermocouple wire into the pilot light would degrade and prevent the boiler from lighting as the signal the pilot was on wasn’t received and so the safety valve would shut off preventing the boiler from lighting.

    • Steve permalink
      November 22, 2020 11:36 pm

      My reverse aircon heat pump in South of France lasted ten years and needs an expensive service with re gassing. It was always useless after October and until March.

      • Ben Vorlich permalink
        November 23, 2020 11:21 am

        That’s not good news for my neighbours (French) in Limousin, who’ve just had an old oil system replaced by a heat pump system.

      • Bloke back down the pub permalink
        November 24, 2020 7:59 pm

        Something which I’d not considered. When you think of how often some car’s AC needs re-gassing then the likelihood of heat pumps needing frequent attention to keep going grows. BTW, in order to provide the heat boost needed for twice a day heating, the most durable and reliable solution would be . Unfortunately, however good, it still adds an extra layer of cost.

    • Nancy & John Hultquist permalink
      November 23, 2020 1:44 am

      Ours is a 1998 Trane XL1800 (USA) that replaced a failing heater/AC.
      We have it serviced every two years; have had minor adjustments. SEER is the acronym for Seasonal Energy Efficiency Ratio; cooling efficiency of the heat pump. What that means, I have no idea.
      Higher numbers are better. SEER 16 is considered “good enough”, but in 2020 the best is 24.

    • November 23, 2020 9:50 am

      It’s probably an unfair comparison, but my fridges never seem to last more than five years.

      The CCC reckon the same as boilers though, about 15 yrs

      • Dave Ward permalink
        November 23, 2020 11:57 am

        “My fridges never seem to last more than five years”

        I’ll find out how true that is in another 3 years! I replaced my upright fridge/freezer in 2018 because the old one (nearly 20 years old, as I recall) was using nearly twice as much ‘leccy as new equivalents claimed. I’ve kept a chest freezer (also around 20) as its consumption is still comparable to newer models. Our Creda tumble dryer was 42 last month – but the boiler I can’t be sure about, although the installation manual was printed in 1991. Undoubtedly a new one would save 30-40% of gas, but my usage is low enough to mean the payback period would be at least 15 years, by which time the replacement would need replacing…

    • November 23, 2020 11:27 am

      I bought a villa in Spain and 20 years agho fitted 5 extra ASHPs. All are working perfectly, although I suspect that they will require regassing in the next 2 to 3 years, and the gas is banned, so they will have to be scrapped.

      Last year I replaced the 1 ASHP that was fitted to the villa when built in 1985. It was working perfectly, but needed regassing, so had to be scrapped.

      My experience with 7 ASHPs is that they have a very long life span, and are extremely reliable. Never seeming to go wrong, just losing gas over time, and most units that are about 10 years old cannot be regassed, due to change in regulations regarding the permissible gas.

  12. MrGrimNasty permalink
    November 22, 2020 10:30 pm

    Could be a low wind power situation later this week looking at the forecast, high pressure over N.Sea and UK for several days at least, Scotland onshore may just stay in a bit of wind around the edge, depends…… Peak demand will also be up, likely to be some of the chilliest weather so far. As ever, caution, even 2 day forecasts are not worth tuppence!

  13. MrGrimNasty permalink
    November 22, 2020 10:46 pm

    Years ago whilst researching noise issues I became aware of air conditioner noise in Australia. I should imagine similar problems will apply to ASHP in the UK. The residential day/night limits:- 45db(a) is very quiet/35 even more so, but even a hum at that level will drive people potty. Difficult to see how there won’t be millions of people adversely affected by noise in the UK’s dense housing stock.

    “Noise from air conditioners can disturb neighbours, disrupt their sleep and interfere with their normal daily activities (listening to the TV and talking on the phone). Air conditioner noise can range from being a nuisance to actually damaging people’s health and is a common cause of noise related complaints.”

  14. Tim the Coder permalink
    November 22, 2020 11:45 pm

    “Has anyone any reliability and durability data ?”

    Not of a heat pump as such, but I’ve had basically the same equipment dehumidifying a poolhouse, and each compressor has lasted less than 15 years in intermittent usage. There have been two other repairs and 3 regasses in that time.

    So expect major demands on HFCs to regas, and total replacement atleast every decade: heating a house will be far more demanding duty cycle. Oh, and every leak in the underfloor heating loop will mean a new floor throughout. I presume this means heating upstairs is out?

    And the easiest way to silence a noisy unit nearby….well, wirecutters are cheap…and snip the coolant pipes and it’ll need regassing, not just a sparky.
    How soon until regassing the heatpumps is verbotten?

    • November 23, 2020 11:30 am

      See my comment above on reliability. No problems in over 20 years. Last year replaced a unit that had been in operation for 34 years and was working perfectly but needed regassing, but had to be scrapped because of prohibitions on the gas used.

  15. Meridan Bennett permalink
    November 23, 2020 4:50 am

    I lived with a heat pump in Colorado, USA – it gets down to -15C here and sometimes older. Miserable experience – the thing ran all the time, and the air from the vents was barely warmer that ambient. I would not recommend.

    • Meridan Bennett permalink
      November 23, 2020 4:50 am

      edit: colder

  16. November 23, 2020 8:22 am

    Paul, doesn’t that mean that a good proportion of 25 million 2.5 Kw immersion heaters will all turn on after people get washed / showered in the morning !?

    • Russ Wood permalink
      November 23, 2020 8:58 am

      Here, outside Johannesburg, we have a solar water heater. Now, this is nice – in summer, we get the geyser at 70 degrees. But in winter, when it’s cloudy, we need to use the electric immersion heater. Fortunately, part of the solar control rig lets us set three timers for heating – an hour each for early morning, another for suppertime, and one more for my evening shower. And for whenever we need hot outside the schedule, there’s always the magic ‘on’ button. It DOES save some money, but then this is the African Highveld! I can’t see it being much use in Britain (the last time I was there in June 1981, the temperature went from 4 degrees to 8 maximum!)

      • November 23, 2020 11:34 am

        My next door neighbour in Spain has solar hot water for domestic hot water supply. I think that he has a 400 litre tank. It is fitted with an elecitric immersion heater for back up. The solar unit provides all the domestic water requirements for about 9 months of the year. Over the winter months the electric immersion heater is required, from time to time, during cloudy periods or when his house (4 bed) has high occupancy. Normally, it is just the 2 of them, so they do not use that much water.

  17. Phoenix44 permalink
    November 23, 2020 9:28 am

    Has there ever been any large-scale government scheme that hasn’t ended up costing at least 50% as much as forecast, taken at least twice as long as forecast and having running g costs at least 25% higher for performance 25% worse than forecast?

    So let’s just apply those factors to these schemes.

    • November 23, 2020 11:35 am

      The over spend is always double to tripple. Just look at where HS2 is heading, and when is cross rail going to be finished?

  18. Coeur de Lion permalink
    November 23, 2020 9:51 am

    Turning away from heat and electricity, what about pipework? 19 million is it? Better start right now manufacturing. I guess we’ll all have to install our own as there won’t be the labour, even with Conservative-generated unemployment. I don’t want to dig up my garden thanks – how does it work in a flat – using the window-boxes?

  19. November 23, 2020 9:53 am

    the more I look into heat pumps the less I like them.
    One significant factor is comparing a gas boiler to a heat pump. A gas boiler uses the fuel directly, the heat pump uses electricity which has losses all the way from generation, dtransmission and distribution. I would guess that it’s not far off 50% the energy input to a heat pump from the same quantity of gas consumed by a household boiler? That doesn’t do the COP much good.

    • November 23, 2020 11:38 am

      If you look at the difference in proce between electricity and gas, the COP doe not even level the playing field, and we all know that electricity prices are going to double, just look at the cost in Germany.

  20. MrGrimNasty permalink
    November 23, 2020 10:22 am

    For Ed Davey and all delusional climate flakes, it’s never enough!

  21. November 23, 2020 12:22 pm

    “According to the Tradesmen Costs website, heat pumps would range from 6 KW for a terraced house to 9 KW for a typical detached” I have already pointed out (in your first post) that these figures cannot possibly be right. I have a 1,500 sq ft detatched villa that has 28KW of output, and I do not consider that it has over capacity. It has 6 ASHPs which is based upon the recommended room size (largest room size 55 sqm which in itself is the sixze of a 1 bed flat), as per the adverts of the main manufacturers of ASHPs.

    You only have to look at what is advertised on the market by Daikin, Daitsu, Fuji, LG, Mitsubishi, Panasonic, Samsung, Valiant, to see what they recommend for 25 sqm rooms, 30 to 35 sq m rooms, 40-45sq m rooms etc, to see that 6 to 9 KW output is pure fantasy.

    So for example, the 12,000 btu LG S12ET.UA3 (latest R32 gas) listed at €1,439, but on black Friday sale at €411 is a 3.5/4KW unit suitable for max 32sqM, rated A++ .

    A Samsung AR09TXHQASINEU + AR09TXHQASIXEU which is a 9,000btu (R32 gas A++) 2.6/3KW unit is advertised suitable for maximum 25 sqm room The 12,000 btu model in this series is a 3.5/3.8KW unit is advertised suitable for 30 sqM maximum.

    I am sure that the manufacturers have a far better understanding of the performance of the units that they manufacture than does “Tradesmen” Of course, it is possible that Tradesmen are looking at unrealistically insulated properties, which are far beyond the majority of old UK housing stock, and are thereby stretching the units beyond the manufacturer’s own room size recommendations..

    At a stretch a 6 KW unit could heat a 1 bedroom flat, with heating in the lounge and bedroom, but no other rooms. if you wanted to heat the kitchen you would have to add a 2.5 KW on top. I would suggest that the figures that you use needs to be doubled to between 12 to 18KW.

    • November 23, 2020 1:51 pm

      The Element Energy study was also based around 5 and 8 KW systems in terraces and semis .

      Of course, the 5 and 8 KW systems trialled by Element in Manchester may not heat houses as well as proper gas central heating!

    • November 23, 2020 2:35 pm

      There’s more information here Richard:

      Generally, the bigger the house the bigger the heat pump. Depending on heat loss, property age, and room types, a 100 sq m house may need a 4kW ground source heat pump or a 5kW air source heat pump. This doubles to 8kW or 10kW respectively for 200 sq m houses.

      200 sq m is a typical detached hose, so 10 KW is in line with the figures I used

      • November 23, 2020 4:53 pm


        I am not talking about ground based heat pumps, or air to water heat pumps, but rather the standard split ASHP that can easily be fitted to ordinary homes. I have bought 6 ASHP and in the course of doing that I have viewed 100s of adverts from all the major manufacturers so I know what the manufacturers claim for their products. If anything, a manufacturer will over puff their products, not undersell its capacity. It may be that if you have a super super insulated home, that most UK old housing stock does not have, and can never be adapted to have (at least not at reasonable cost), you would get better performance.

        The adverts I mentioned above, were looked at today. So LG (a make you have no dount heard of ) advertise their 4KW model suitable for max 32sqm. So your 200 sq m detatched house would require 6.25 of these units, totalling 25KW.

        Samsung (a make you have no doubt heard of) states that its 3KW model is suitable for max 25sq m. So your house of 200 sq m, will require 8 of these totalling 24KW.

        These are the latest inverter designs with the latest gas. They are both A++ rated. My Daikin, that I referred to earlier is one of the very few models that is rated A+++ for both heating and cooling.

        I have not fitted my 150 sq m property with 28KW, for the sheer fun of it. As I say, it does not have over capacity. That is real world, not fantasy world experience. I have my air con running at the moment, the sun has set, the outdoor temp is presently 17degC, and the room is sufficiently warm to wear shorts, no socks, and a very light jumper. In just a T shirt, I would probably be a little cold sitting down, but fine if I was moving around.

        I would suggest that you look to see which manufacturer markets their 8KW or 10KW split system ASHP as suitable for 200 sq m.

      • November 23, 2020 5:14 pm

        Are you saying heat pumps will cost much more, cost even more to run, and need even greater extra grid capacity?

        It is well accepted that you need much better insulation than most houses have to get the same warmth as a gas boiler provides – that is another reason why they are such a waste of time

        BTW – I don’t know what you are looking at, but I am looking at the ones the CCC is!

  22. November 23, 2020 12:40 pm

    I will add another example, the Haier (cheap make) AS50TDDHRATH + 1U50MEEFRA (pirce €1,043, black Friday sale €704), is a R32 gas A++ 5/5.2 KW unit maximum room size 45 sq.M. But when you add additional internal units (in this case 1U50MEEFRA) the efficiency goes down, and many pumps struggle handling 3 internal units (with different length internal piping). Split units are at their most efficient on a 1:1 basis, rather than a 1:2 basis, and even worse on a 1:3 basis.

  23. It doesn't add up... permalink
    November 23, 2020 1:39 pm

    When the weather gets cold, my heating goes on constant. Of course in practical terms it means that the boiler runs intermittently when the thermostats switch it on and off in a hysteresis loop. So I’m not sure about the claims about twice a day heating. The reality is that when it gets cold heating demand soars, and heat pumps and thermal stores are not going to be able to do much to soften the blow.

  24. Stephen Lord permalink
    November 23, 2020 4:30 pm

    We have heal p u mp s. In our N. York city apartment they are. usedonly for AC and has is uses for heating . In Ca. it is usedfor A C and heating we always use a timer to control them, Plus the thermostat. turns the system on and off while running. You can improve the COP with a bigger external heat exchanger. I would assume most people will want the split systems which do both and blow hot or cold air as needded

  25. November 24, 2020 3:50 pm

    Government’s heat pumps plan “doomed to failure”
    24 November, 2020 – Modern Building Services magazine

    “without a meteoric increase in training and investment to upskill the workforce, this goal will be unachievable”…“Given that the sector has comprehensively failed to train the workforce to fit new gas boilers correctly, it seems doubtful that engineers will receive the training they need, without intervention.”

  26. MikeHig permalink
    November 25, 2020 5:01 pm

    In the interests of clarity, please could figures be quoted as either output (heat) or input (leccy) – ideally both?
    That would make comparisons easier because we are looking at both the amount of heat needed for a given size of property and the power required to provide it.

  27. Pancho Plail permalink
    November 25, 2020 9:20 pm

    My next-door neighbour had a house built on a plot next to me and installed underfloor heating. Less than 10 years later they had to have it replaced due to leaks; replacement involved pneumatic drill to remove the concrete the piping was embedded in. They sold 2 years ago and the new owner found when winter came that the underfloor system had failed a second time. He has replaced it with conventional radiators.
    The problem seems to arise from the fact that underfloor systems run at a higher pressure in order to circulate water through great lengths of small bore piping, hence stressing joints and pipes.
    I am willing to bet the costings for heat pumps don’t factor these things in.

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