Skip to content

Heat Pumps Will Overwhelm The National Grid

November 21, 2020

By Paul Homewood


 See the source image


We have been looking at the potential impact of electric cars on grid capacity, but this is likely to be swamped pretty quickly if the roll out of air heat pumps is carried out as planned,

The government’s plan is to be installing 600,000 a year by 2028, some of which will be in new build homes.

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. [The 200 GW is overstated – see correction below]

This assumes that they will all be working simultaneously, a not unreasonable assumption, given the need to heat houses in the early morning.

This quite clearly is a non runner, which is why the Committee on Climate Change has been pressing for hydrogen hybrid boilers, which can provide most of the heat on cold winter mornings.

However, we don’t have a hydrogen network, and are unlikely to for many years to come. The official plan is to set up a pilot scheme by 2030, but it will take many more years to extend it nationwide.

600,000 heat pump installations a year would mean an extra 5 GW of capacity would need to be added each year, so even by the mid 2030s, we would need an extra 35 GW.

I can honestly see a scenario where we are still allowed to use our gas boilers until hydrogen is rolled out, despite having a heat pump installed. (While at the same time being implored by National Grid to turn our heat pumps off!)


I have also been taking a fresh look at costings. When extra insulation is added, average costs are likely to be well in excess of £10,000:



And despite the misleading advertising often put out, running costs for an ASHP are much higher than a gas boiler.

A typical house uses about 11,000 KWh for heating and 4,000 KWh for hot water. Current gas prices are 2.5p/KWh, so the annual bill would be £375.

A heat pump working at COP 3.0 (ie efficiency of 300%) would consume 3666 KWh of electricity for heating alone. But heat pumps are inefficient when it comes to hot water. There is a particular issue with legionella, which thrives at water temperatures below 60C – a typical heat pump reaches about 50C.

The simple option is to install a separate electric water heater, which would increase the installation costs. In total then, you would need 7666 KWh of electricity for heating and hot water, which at a current price of 14.5p would cost £1112 a year, making you £737 worse off.

There are more complex solutions to supplying hot water, such as incorporating an auxiliary hot water in the heat pump system to raise the temperature to 60C. But it is not evident that running costs would be much less.

Better get your winter woollies out!


I wrote:

  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 8 KW refers to energy output, not input.

None of this affects the costings of course.

I’ll issue a more detailed update tomorrow.

  1. November 21, 2020 12:51 pm

    “Better get your winter woollies out!”
    Agreed. A much better way of spending taxpayers’ money would be to provide the entire populace with two free woolly jumpers. It would cost less and give much-needed work to Cumbrian sheep farmers.

    • Robert Christopher permalink
      November 21, 2020 1:05 pm

      What’s wrong with selling knitting needles and wool, with instructions available on the internet?

      Taxpayers money not needed!

      • It doesn't add up... permalink
        November 21, 2020 2:41 pm

        Indeed, we may get to the tricoteuses watching Mme Guillotine yet.

      • Duker permalink
        November 21, 2020 7:19 pm

        Sorry , but the cliams here dont add up
        “If we take 8 KW as the norm, 25 million homes would potentially need 200 GW of grid capacity, purely for heating alone.”

        I have 2 heat pumps and they dont draw anything like that maximum capacity even on start up. Sure I live in more temperate climate but the 5.5kw pump draws about 400W when running normally. The noise is very low

        I dont believe for most in Uk heat pumps will be better than the gas powered boilers with radiant heaters. Its a good system that works.
        And yes the downside of heat pumps is that on very cold mornings when it gets below 5C the outside unit ices up after say an hours running. ( It stops and ‘reverses’ to melt the the ice, as a heat pump it can heat and cool inside so works both ways but doesnt blow cold air inside when it does so)
        For those reasons gas is likely better in UK where winter temperatures are below 5C more often

      • November 21, 2020 8:12 pm

        Yes, you’re right Duker

        My mistake – the 8KW is energy output, so based on COP 3.0 we’re looking at 2.4 KW.I’m adding a footnote to the post.

      • Harry Passfield permalink
        November 21, 2020 7:50 pm

        Duker, be fair, we are discussing heat pumps for the UK climate.

      • Duker permalink
        November 21, 2020 8:16 pm

        Another point about the 8KW. Thats the max heat output, not the max power supplied.
        The way HP work is the max heat output is 3-5 times that of the power input .
        Say if its running an output of 3kW – which is a lot , then the load is 1kW or less. Once the house has reached equilibrium temperature the power out put required drops down as well, maybe 1 to 1.5kW which would mean say 300-500W power draw.

        thats not to say converting from gas is a great idea when you have colder winters, but the facts of heat pumps have to be compared.

      • November 21, 2020 8:20 pm

        See my previous reply.

        However, it is peak capacity which is at issue, not normal working load

      • Duker permalink
        November 21, 2020 11:11 pm

        The other point is that the heat pump is for normal domestic heating , not hot water. I have a 3kW electric hot water cylinder. And thats resistive heating so the output and load are matched. So the 3kW plus has to be added to the domestic load of the heat pump
        There are hot water heat pumps but as its heating only its cheaper to have them as a separate unit rather than ‘reverse cycle’

  2. StephenP permalink
    November 21, 2020 12:52 pm

    Some very green friends installed an air source heat pump
    Firstly, the noise it made annoyed the neighbours.
    Secondly, it doesn’t work very well when the outside temperature is low, so they have electric fires in each room to top up the temperature.
    Extra pullovers are necessary when visiting them in cold weather.
    Lastly, the bathwater never gets above tepid.

    • Dave Ward permalink
      November 21, 2020 5:25 pm

      “Firstly, the noise it made annoyed the neighbours”

      And that is exactly what worries me – can you imagine what it will be like if EVERY house has one of them running all day (and most of the evening)? Once a few have developed loose covers – or some other part that rattles in tune with the compressor – what little quality of life we might still have by then will be completely extinguished…

    • Tonyb permalink
      November 21, 2020 7:15 pm

      Anything below 7 degrees c outside temperature and the performance fall off a cliff so the colder it gets the less useful they become.

      I don’t know if there were lots of them in flats stacked on top of each other if they would steal the neighbours heat thereby reducing the temperature. This is a problem with ground source heat pumps which gradually reduce the temperature of the soil they are buried in thereby reducing their performance over the winter

  3. Robert Christopher permalink
    November 21, 2020 12:53 pm

    This is good news, even excellent news.

    The sooner we get REALLY BAD news, the sooner policies will change, I hope! 🙂

    • It doesn't add up... permalink
      November 21, 2020 2:43 pm

      I assume you plan a winter migration to warmer and sunnier climes.

      • Harry Passfield permalink
        November 21, 2020 7:53 pm

        Oh No!! You can’t go to a warmer climate! Don’t you know, a change of more than 1.5 Deg C will probably kill you – or create and emergency. Don’t Do it!!!!

  4. Mad Mike permalink
    November 21, 2020 1:04 pm

    Its all very well for us that have piped gas but spare a though for those buying new houses when the rule comes in barring gas supplies to these houses.

    I think Boris should get a different girl friend.

    • Chaswarnertoo permalink
      November 21, 2020 1:05 pm

      The history of Art grad. should butt out. Or pass a STEM degree.

      • Ben Vorlich permalink
        November 21, 2020 3:40 pm

        Give her a break, she’s got Theatre Studies as well.

      • Tonyb permalink
        November 21, 2020 7:19 pm

        The degree is for History of art AND theatre studies. So she is able to put on a convincing performance when pleading for green policies.

    • Gerry, England permalink
      November 22, 2020 11:03 am

      Do the rules also ban the retrofit of proper heating such as gas tanks or oil tanks?

      Off-grid new builds are supposed to use wood chip or heatpumps.

  5. Chaswarnertoo permalink
    November 21, 2020 1:04 pm

    Why I am considering a heat pump run from a solar panel for my barn conversion. Not green, just don’t trust Govt.

    • Robert Christopher permalink
      November 21, 2020 1:07 pm

      It still needs Electricity!

      • Harry Passfield permalink
        November 21, 2020 1:39 pm

        Chas says he will run the pump from a solar panel. So, I am guessing that the pump will do the business based on a PF for the panel of 11%. Hope we get updates.

      • Ben Vorlich permalink
        November 21, 2020 3:42 pm

        I’d be interested in how that works at night, usually when minimum temperatures happen

    • It doesn't add up... permalink
      November 21, 2020 2:44 pm

      I assume you plan a winter migration to warmer and sunnier climes.

      Comment in wrong place initially.

      • November 21, 2020 7:21 pm


        Do have faith. If you believe the impossible then it will surely happen.

    • Beagle permalink
      November 21, 2020 6:02 pm

      So you will be able to heat your house when it’s nice and sunny in summer but the time you need the heat is when you get very little energy from your solar panels, winter.

  6. Stewart Herring permalink
    November 21, 2020 1:14 pm

    Has anybody thought about all the water these hydrogen burners will produce?

    • Joe Public permalink
      November 21, 2020 1:37 pm

      Just posted below ↓↓↓ 😀

    • November 21, 2020 2:10 pm

      I spoke to my daughter yesterday about this, and she did not know that water vapour was a GHG, even though she is the rare example of a young person thinking that this alarmism is just a scaam. Most people are unaware that water vapour is a GHG, and the most abundant one on this planet.

      • Mike Jackson permalink
        November 21, 2020 5:53 pm

        Careful, richard, or the next thing the hard-of-thinking will be looking to ban is gaseous dihydrogen monoxide!

      • Harry Passfield permalink
        November 21, 2020 6:26 pm

        Richard, without any snide, I wonder what her answer would be if she were asked to bamdvtge took three gases in the atmosphere. I ask only because I know my grandson is about to face this,

      • Harry Passfield permalink
        November 21, 2020 7:59 pm

        Richard, I don’t know where the gobbledygook came from. I was wondering if your daughter was asked about the top three gasses in the atmosphere were.
        Sheesh, sorry.

      • Gerry, England permalink
        November 22, 2020 11:24 am

        Penn & Teller did a great video spoof on going round and getting people to sign a petition to ban the use of dihydrogen monoxide and if I recall nobody realised they were signing to ban water. Classic. Probably censored by Youtube now.

      • dennisambler permalink
        November 22, 2020 3:28 pm

        From 2018, 4 months left on iplayer

        Helen Czerski Physicist – Fundamental Physical Laws of the Universe

        9 minutes 30 seconds in,

        “The molecular structure of water is key to why the Earth’s temperature is warmer than you might expect. Hydrogen bonds are key to water’s influence on Earth’s temperature. Hydrogen bonds are so strong that it takes a lot of energy to break them. And that means that the water in the earth’s oceans can absorb a huge amount of heat energy from the sun, without changing from a liquid to a gas.

        The oceans act as a huge store of energy and as they move they distribute heat from the equator to cooler latitudes north and south. But it’s not only in the oceans that water plays a part in earth’s temperature. The bonds between water molecules are very strong, but provide enough energy and they’ll break apart and you get what’s all around me in the air here – water vapour. And in this form, as vapour in the atmosphere, water has perhaps its greatest influence.

        The atmosphere traps the sun’s heat, a process known as the Greenhouse Effect and although we tend to associate this with carbon dioxide, it is actually water vapour that accounts for much of the trapped heat.”

        Still talking about “trapped heat” but dissing CO2 as a planetary thermostat, on the BBC.

  7. Bill Scott permalink
    November 21, 2020 1:18 pm

    I have a heat pump and quite like the cooling in summer and heating in winter. My controls are computerized and in the morning after a cold night “auxiliary heat” is called up which in my case is my oil furnace, some people have gas of electric aux heat. Relying solely on the heat pump means it would take a long time to reach daytime setting.

    • MrGrimNasty permalink
      November 21, 2020 3:35 pm

      And it doesn’t strike you that this is a stupid engineering solution?

      I’m not being personal, I mean generally, the whole ‘green’ business is stupid and inefficient, you have to double up, so that’s a whole second set of fires, boilers, etc. that have to be manufactured and maintained, just as windmills need a gas power station just in case.

      It defies credibility that this can be anything but ruinously expensive for consumers, but more importantly, that it won’t be worse for the environment.

      And in your nicely insulated house (presumably), you are now using energy for cooling in summer in addition to heating in winter, further offsetting energy ‘savings’.

      And all that insulation and complicated heat recovery ventilation systems and heat pumps just uses more energy upfront in manufacture – than a more simple/direct system, it’s energy use displacement.

      There’s a common sense law in nature/life, you don’t get owt for nowt.

      • Ben Vorlich permalink
        November 21, 2020 3:53 pm

        Been my argument against renewables, (apart from why are they needed?) We had a system which basically was seeing gas replacing coal as a natural process for main supply, nuclear base load,hydro in its two forms and interconnectors covering all needs and eventualities. We now have gas, nuclear (not enough soon), wind, solar, hydro, biomass, some residual coal, batteries, diesel, interconnectors, little generators in garages and goodness knows what else not covering all eventualities.

      • Chilli permalink
        November 21, 2020 9:56 pm

        But Ben, “diversity is our strength” see – even when it comes to duplicating cheap reliable energy supplies with a parallel system of costly unreliable ones.

      • Gerry, England permalink
        November 22, 2020 12:01 pm

        You have missed biogas, Ben. Can’t leave out a process that causes increased traffic and wildlife destroying effluent leaks.

        I quite agree that any system that is designed to fail and require a back up from the start is engineering lunacy. The concept of a back up is often sound as is avoiding a Single Point of Failure. A sailing yacht needs a small engine to move around harbours and moorings, but by restricting its use it requires a small fuel store and a small engine.

        Then look at a hybrid car that has an engine and fuel tank, and a heavy load of batteries and heavy electric motors. If you made the engine big enough and connected it to the wheels it would drive the car forward – who’d have thought? Even if the engine is now a small generating system to cover for the short range of the batteries and the problems with recharging it still adds extra weight and cost, and is still going to be banned in 2030. I read a critique of car manufacturers continuing to build proper cars even it they are not selling – could this be good forward planning to meet the huge demand in 2029?

  8. Richardw permalink
    November 21, 2020 1:25 pm

    Air source heat pumps do not work well in cold weather

  9. Joe Public permalink
    November 21, 2020 1:35 pm

    “… the Committee on Climate Change has been pressing for hydrogen hybrid boilers, which can provide most of the heat on cold winter mornings.”

    If folk have a hydrogen boiler, they have no need for a heat pump.

    But wait … Hydrogen combustion produces approx 60% more of that evil greenhouse gas water vapour than does natural gas combustion, per useful kWh

    Click to access hydrogen-logistics.pdf

  10. November 21, 2020 1:36 pm

    Many years ago I looked into installing a water-sourced heat pump using the river at the bottom of my garden. It took about 5 minutes of research to show it was a non-starter (economically and technically) and so I continue to use my oil-fired central heating system and a wood-burner.

    • Ben Vorlich permalink
      November 21, 2020 4:10 pm

      The house I grew up in in Perthshire was pretty remote, 2 miles to nearest neighbour. No mains electricity heating was by open fires, and paraffin heaters, cooking and hot water by Rayburn, back up cooking 2 ring Calor cooker, Calor also for lighting in part of the house.

      In the 45 years since I was last resident it has been totally renovated, mains electricity and undersoil heat pump heating, and is now a B&B I hope that it is warmer than when I lived there because it was a great place to grow up and learn to appreciate modern technology.

      • Dave Ward permalink
        November 21, 2020 5:33 pm

        I’m sure it is warmer – UNTIL the mains goes off (which being “Pretty Remote” is probably several times each winter). That’s when the occupants will wish they had some of your “Old Tech” available…

  11. CheshireRed permalink
    November 21, 2020 1:47 pm

    Boris probably hasn’t costed any of this properly, and certainly won’t have done with advisors likely to tell him numbers he didn’t want to hear.

    It’s all so utterly preposterous. Hard to believe this is the UK rather than fantasy island.

  12. Paul H permalink
    November 21, 2020 1:49 pm

    Chaa’s link is a devastating exposé of the Climate Change Brigade’s claim man’s fossil fuel emissions are building up in the atmosphere and thus causing Global Warning.

  13. November 21, 2020 1:53 pm

    I do not know where you get these figures from but they seem wildly inaccurate to me. I would have thought that the average householder pays double for gas to heat their houses.

    As regards ASHP, I have a 3 bed detatched villa in Spain, it has 28KW of ASHPs. A 5KW ASHP will heat a room of around 35sq m. A 8KW will heat a room of around 40 sq m. A bedroom needs a 2.7 to 3.2 KW ASHP.

    Air to water heat pumps are extremely expensive, and very expensive to run unless you have underfloor heating that only requires a water out temperature of around 35 to 38degC. Most Air to water heat pumps only push out water at 55degC, but some will manage 65degC, but these are really back to back heat pumps. Conventional radiators are designed for water temp of between 70 to 80 deg C, so most air to water heat pumps will not produce the goods which means that either one has to buy special low temperature radiators which cost about 3 times as much as ordinary ones, or you have to install at least 50% over capacity to take account of the fact that the water temperature is about 20 degC below that produced by a gas boiler.

    The cost of running such a heat pump becomes very expensive when water temperature is set to above 50degC. The efficiency falls off rapidly, and of course the colder the outside temperature, the worse the performance.

    Modern ASHP have a far better efficiency factor than you are suggesting. The one I bought last year was between 8 to 9 efficiency depending upon whether heating or cooling. That was with outdoor temps of around 10 deg, the UK does not have that sort of temperatures during the autumn/winter/spring evennings. The efficiency drops off a lot if the ambient outdoor temperature is below freezing.

    • ThinkingScientist permalink
      November 21, 2020 3:20 pm

      According to my energy bill the price of gas per kWh is 1/5 the price of electricity.

      I currently get charged:

      gas at 2.62p per kWh
      Elec at 13.3p per kWh

      My last gas bill (usage) for the summer quarter was charged at £68.73.
      If that had been electric it would cost £348.90 for the same energy, an increase of £280. That’s for the summer, full year it would be at least 4x that increase, so well over £1,120 per annum on my bills.

      Of course as gas is phased out of electricity supply, I can only presume the cost of electricity will rise as well. If gas currently supplies 30% of annual power for electricity then phasing it out is likely to increase my electricity as well:

      13.3p = 0.3 * 2.62 + 0.7 * Eprice so (13.3 – (0.3*2.62))/0.7 = Eprice = 17.88p/kWh

      So if 30% electricity supply is currently from gas and we get rid of it from power generation, my back of the envelope calculation says the price of electricity will rise about 34%. That means the energy supplied currently to heat my home and water will rise from £68.73 for the summer quarter to £469, nearly 700% increase!

    • Joe Public permalink
      November 21, 2020 3:59 pm


      “Modern ASHP have a far better efficiency factor than you are suggesting. The one I bought last year was between 8 to 9 efficiency depending upon whether heating or cooling.”

      Not according to the Building Research Establishment’s “Domestic Annual Heat Pump System Efficiency (DAHPSE) – Estimator – BETA”

      • November 22, 2020 2:43 pm

        I bought a Daikin which is one of the most expensive manufacturers, and has an excellent reputation for quality and reliability. At the time, the model I bought was their most efficient. I have just checked, it has a SEER of 8.7 (which is cooling) and a SCOP of 6.2 which is heating. So I was mistaken on the SCOP, save that in Southern Spain, the ambient outdoor temperatures are usually significantly higher than the standard, so that one could reasonable expect, save on the coldest nights, a heating efficiency of better than 6.2. For example, a couple of days ago when I was using it at night, the out door temperature was 17 deg, which is considerably higher than the standard at which the SCOP assessment is given.

        I am simply telling readers what is on the market. I am familiar with the subject, since I have 6 ASHPs, and my neighbour has an air to water heatpump (also Daikin). He has underfloor heating so that set up works very well, but is something that can only be put in a new build house, and difficult for the upstairs unless the upstairs has a concrete floor. I have thought of putting in an air to water heat pump but it means digging up not only all the tiles, but also the concrete flooring below, and of course requires removal of the kitchen cupboards etc. It is a large and expensive task, so better to have a system with radiators, hence my comment on radiators.

    • Ray Sanders permalink
      November 21, 2020 3:59 pm

      I am sorry to advise you that your figures are incorrect and simply defy physics. I suggest you study the work of Sadi Carnot. The best CoP you are likely to achieve in the UK winter for any type of heat pump is 4 and an ASHP will be at very best only 3.

      • November 22, 2020 3:14 pm

        I am not commenting on what one might realistically get in the UK,, given UK temperatures, but rather what is on the market and sold according to EU standards. I have checked, the EU energy sticker for the appliance, states that it is certified as SEER 8.7 (cooling) and SCOP 6.2 (heating). So I was slightly wrong on the heating, but I probably had in mind that in Southern Spain, night time temps are usually significantly higher than the standard reference for SCOP assessments. Of course, I made the point that in the UK they would be less efficient.

        Unlike most people commenting, I actually have 6 split ASHPs, but as I point out they total an output of 28KW, for a 3 bed detached villa, of approx 140sq m. A split system is where you have an individual outdoor unit (the pump) and an individual indoor unit. It is possible for the pump to run more than 1 indoor unit, but this involves more complex installation, and adversely impacts upon the efficiency of the system especially where unequal lengths are involved between indoor unit and outdoor unit.

        I do not see how a house could possibly be heated with a 8KW ASHP. That is where the fantasy lies. An 8 KW ASHP is advertised for rooms of about 40sq m, so around 430, max 500 sq feet. I do not know what the average size of a UK home is, but if we are talking about houses, not small flats, I guess that it is in the region of 1,000 sq feet, so one is looking at a minimum of about 16KW ASHP. A larger house will need more, a small flat less.

        One of the major issues is that there is a world of difference between Scotland and the south coast of England.

    • It doesn't add up... permalink
      November 21, 2020 4:14 pm

      I tried plugging in a well known Westminster postcode on the tariffs for Octopus. Some indeed were as low as about 2.5p/kWh for gas with a standing charge on top. Others involving longer fixes were over 4p/kWh. I looked up kerosene prices yesterday, which are below 3p/kWh with no standing charge. They include fuel duty.

      Not sure about your claim of 8-9 efficiency. It must be some different scale I think, like marks out of 10 related to a theoretical maximum or something, or perhaps measured at a rather low output temperature.

    • November 21, 2020 7:18 pm


      I can only refer you to the Tradesmen’s website I used:

      “A typical value for COP could be 3.0 at an outside temperature of 7°C. ”

      The Greenmatch website, which promotes all things green, also notes:

      “t they often achieve a 200-600% efficiency rate,”

      Obviously you get good efficiency when it is warm outside, when you don’t need heating.

      The costings also come from those two sites

      As for energy prices, the ones I quoted are from the new contract I have just taken out with Avro Energy

      • November 21, 2020 7:46 pm

        I think when the time is right we need a nalopkt scientific investigation trip to suss out the heat pump situation at Richards detached villa in Spain.

        I reckon it might take a week.

      • November 22, 2020 2:45 pm

        See my above comment. These figures are EU certified.

      • November 22, 2020 4:27 pm


        I Don’t really care about the figures I just want a cheap holiday, I mean proper scientific investigation

  14. Harry Passfield permalink
    November 21, 2020 1:59 pm

    I have unashamedly pinched this from a comment under Charles Moore’s comment on Green nonsense in today’s DT. Worth a read (his article and the comment) until he cops out with the line: “None of the above impugns the need to search for low-carbon energy.” Yea Gods! I intend to leave a comment to advise him to have a chat with Lords Lawson and Ridley.

    Quote follews:

    “I installed an air heat pump. It works very well, but requires you to:

    – install underfloor heating

    – your house to be completely reinsulated (more than 15 cm on every wall)

    – only use electricity

    – tolerate “hot” water at only 52C

    – outdoor slab for that unit to sit on with piping to inside.

    – have space for all the tanks, valves and pipes (mine looks like a submarine)

    – spend staggering amounts to make it all work.

    Yes, they are a nice way to heat your house and water with 30-40% of the electricity one would normally use, but it costs more than £100,000 to do.”

    • It doesn't add up... permalink
      November 21, 2020 4:18 pm

      !,,or at least 85 years of dual fuel heating bills according to OFGEM. Like Grenfell Tower the true payback probably exceeds 200 years, or the life of the building.

  15. Gamecock permalink
    November 21, 2020 2:05 pm

    Politicians calling for the electrification of the country. While destroying centralized energy production. What could go wrong?

  16. JimW permalink
    November 21, 2020 2:11 pm

    Its never going to happen. Natural gas heating ( and oil in the country areas) will be here for a long time, thank goodness.

    • ThinkingScientist permalink
      November 21, 2020 3:23 pm

      Gas boilers in new build houses are to be banned from 2025

      • Dave Ward permalink
        November 21, 2020 4:04 pm

        “The prime minister’s pledge to ban gas boilers from new homes by 2023 has been withdrawn”

      • ThinkingScientist permalink
        November 21, 2020 4:50 pm

        Thanks Dave, I stand corrected….and its potentially good news. I see that BBC Horrobin article was only posted in the last 24 hours…may change yet

      • Joe Public permalink
        November 21, 2020 4:55 pm

        Gas boilers fired by Natural Gas / LPG; not for gas boilers fired by manufactured (what irony) ‘bio-gas, or Hydrogen gas.

      • Joe Public permalink
        November 21, 2020 5:00 pm

        I should have added there’s no proposal to ban natural gas / LPG (or even oil) boilers being replaced in existing properties after 2025.

        As gas will continue to be approx 1/4 the cost of electricity per useful kWh, there’ll be a healthy replacement market for gas boilers – possibly into the 2030s.

      • ThinkingScientist permalink
        November 21, 2020 9:14 pm

        My gas is currently 1/5 the cost of electricity.

  17. ianprsy permalink
    November 21, 2020 2:22 pm

    My council is planning a small estate to do just that. The test will be whether they can sell them without telling lies.

    • ianprsy permalink
      November 21, 2020 2:24 pm

      This was a response to Mad Mike’s post above. Don’t know how it got here.

  18. SimonformAshby permalink
    November 21, 2020 2:34 pm

    I think they should do a limited trial first. I am thinking Boris Johnson and his cabinet.

    • PPadd permalink
      November 22, 2020 5:17 pm

      I wonder how Roger Harrabin’s home is heated /insulated? He should record a Panorama programme about it.

  19. MikeHig permalink
    November 21, 2020 2:35 pm

    Another bit of devilry in the technical details…..starting currents. I think there is a limit on the size of motor that can be started on standard single phase power? A friend was looking at putting in an ASHP but was told he would need 3-phase power.

    Richard V; please could you clarify a few of the figures you quoted?
    Firstly, the 28 kW of ASHP you mention, I assume that is the heat output so the power consumption is what…8-9 kW?
    Secondly, the efficiency of 8 or 9 for the pump you bought recently is dramatically better than the generally-quoted CoP of 3 to 4. I did a quick bit of googling and the best I could find was a CoP of 6 but that was with ambient air at 20 degrees. Would you mind confirming that figure?

    • TomO permalink
      November 21, 2020 3:07 pm

      seconded – some links to spec sheets too if you’d be so kind.

    • Dave Ward permalink
      November 21, 2020 4:12 pm

      “I think there is a limit on the size of motor that can be started on standard single phase power? A friend was looking at putting in an ASHP but was told he would need 3-phase power”

      If variable frequency (i.e. speed) inverter drives are used, I suspect that larger motors could be started & run from single phase supplies than would ordinarily be the case. In fact, I have seen the word “Inverter” mentioned in publicity for Heat Pumps, so this may already be the case. My friends chicken farm employs these drives to run various conveyor belts, and they can be controlled from zero to full speed, or anywhere in between. They’re all fed by 230 volt single phase mains, and then output to standard 3 phase motors.

      • MikeHig permalink
        November 21, 2020 6:44 pm

        Thanks Dave.
        I guess that means more kit and cost are part of the package.

    • H Davis permalink
      November 21, 2020 6:13 pm

      My first hand experience is with a 2100 sq ft house in Pennsylvania USA. The house was built in 1990 to fairly high, but not ridiculously high, efficiency standards for the time. It had R24 walls, R38 ceilings and R6 insulation on the basement walls down to the footings. There was also a lot of effort made to reduce air infiltration/exfiltration. The builder estimated that our extra insulation efforts increased the cost of the house by about 3%.

      I imagine the weather in Pennsylvania might be about the same as the UK. All my temperatures are in F.

      The house had a 3.5 ton (42000 btu/hr) air source heat pump/air conditioner. I had electrical monitoring equipment in place for many years on both the outside compressor unit and the inside air handler. The compressor was a 2 speed scroll type and the circulation fan had several speeds from 400 cfm to 1000 cfm in steps. It spent nearly all its time at 400 or 600 cfm. Auxiliary heat was by a 5 kw resistance element.

      The measuring equipment measured everything that consumed electrical energy in the 2 units; compressor, fan and controls in the outdoor unit and the circulation fan and controls in the indoor unit.

      The compressor ran about 90% of the heating season on the lower speed with the entire system using 1700 watts. On those few times (usually when the temperature was somewhat below freezing) it kicked up to the higher speed it used 2200 watts. The auxiliary heat never came on unless there was a failure of the main unit. When this occurred the thermostat was programmed to maintain 65 degrees instead of the normal setting,

      The compressor had 2 fixed speeds so getting more heat meant running longer. A properly designed system would run continuously when the temperature was at the minimum design temperature which for us was 0 degrees. The air temperature at the registers was about 90 degrees but at extreme low temperatures it would drop to about 85 degrees..

      These units do have some “issues”. Our main problem was in extreme cold; freezing and below. The unit could still produce sufficient heat indoors but, of course would need to run longer because of the lower efficiency and greater heat loss from the house. At these lower temperatures any humidity in the outside air tended to condense on the really cold outside coil and freeze. This eventually produced enough ice to block the air passages through the coil and prevent heat transfer from the outside air to the coil. These systems go through a heating cycle if they detect icing where they reverse the system to cool the inside and expel that heat in the outside coil thus thawing the ice and further reducing the overall efficiency. However, in our case and others I knew about, this defrosting mechanism was marginal at best and our unit would often trip off, set an alarm light and switch to auxiliary heat. It usually was not obvious that this had happened unless you noticed the light on the thermostat so we could be running for some time with the auxiliary (and very expensive) heat.

      There is some noise associated with the outside compressor so locating it away from living rooms or bedrooms is desirable. But in the states these units are very common as far north as Pennsylvania because you get central A/C for about $400 more than a heat pump alone. And installation in new construction is much cheaper than a hot water system. The same ducts work for heating and cooling. If heating was by hot water and a boiler you’d need a completely separate system for the A/C.

      The cost of our unit was about $6000 in 1990 which included the plumbing, electrical and duct work in a house under construction. So a fairly easy installation. All the ducts were in the basement and easily accessible.

      A recently installed (2019) replacement unit of the same size but in a different house, including a gas furnace for heating (the heat pump being used only as an A/C) cost $5000. This replacement didn’t require any new refrigerant plumbing, electrical or duct work.

      This is only one sample of course and I suspect that the retrofitted housing stock in the UK would not be nearly as efficient as our house was. The charming pictures from Tony Robinson’s adventures we see of UK housing here in the USA seem to suggest a lot of stone construction. This is a nightmare to insulate because there is nowhere to put the insulation unless you frame walls in the interior but perhaps more important you must moisture proof the stone wall to prevent water vapor getting into any insulation you install inside. Very difficult to do. There are other techniques like spray on foam but they are expensive and must be covered because they are flammable.

      Heat pumps would probably work in new construction but I don’t think retrofitting the existing stock would ever pay off.

      Know that there are a lot of us here in the states watching you folks as you “volunteer” to be the guinea pigs.for the great experiment. I wish you well but fear the worst.

      H Davis

    • Graeme No.3 permalink
      November 21, 2020 8:11 pm

      The coefficient of efficiency is measured in the laboratory with a standard temperature on BOTH sides of the heat pump. I have seen a figure of 7 but I think 4 is more useful for real situations.
      The name Heat Pump is useful as that is what they do; “pumping” heat in or out of your dwelling; the electricity used goes up (efficiency drops) as the temperature difference increases, and when trying to extract heat from air below freezing you cannot expect an efficiency of better than 2, and in really cold weather (minus 20℃) you would be better with straight electric heating. The suggestion that people should rely on coils in the ground comes, I think, from some public servant who has had a “bright idea”.
      In Australia heat pumps are very handy for cooling; they have the advantage of dehumidify the air if your climate is humid but the water has to go somewhere. In hot dry air not a problem but (from experience) the efficiency is poorer when the outside air is 40℃. One trick was to mist distilled water onto the hot coils which noticeably made the incoming air cooler. The effect lasted a very short time and was usually over before you could get back inside.
      The usual system here has an outside heat exchanger and working fluid is circulated to the inside fan box or ducts. This cuts down on noise compared with a unit in a window, but houses here tend to be more widely spaced.
      Yes, you can start up a 5kW unit from single phase 230V when the heat pump has a built-in inverter.
      Given the climate in England I foresee problems with higher electricity demands in cold weather. Locally I had a heat pump which I used to cool only (although others used theirs for heating) but local temperatures rarely dropped below minus 3℃. Wood fires are very popular (outside the city) as a supply was available and cheaper. I relied on gas heating which was quicker to give warmth. Another advantage (in South Australia) was that gas was very handy when there was no electricity. That might be a consideration if your grid is Boris-ted.

  20. Devoncamel permalink
    November 21, 2020 2:48 pm

    Well, having read the comments thus far, I tend to find myself in agreement. In rural Devon many homes are off the gas grid and my new build house came with an ASHP installed. It works well but takes a bit of getting use to. I have no problem with it other than paying a bit more for servicing, due mostly to lack of competition with available engineers. If it works as a heating solution, no problem.
    I too read the Charles Moore article (DT, 21/11/20) and what struck me was the blind acceptance of our political class of the ‘climate emergency’ and belief in the catastrophic consequences of global warming. Nobody in Westminster dares to question it, the having succumbed to groupthink. As CM alludes to, this is what leads to failure. For the UK economic disaster is looming if we venture any further down the road at full speed to a net carbon zero Utopia.

    • November 21, 2020 3:43 pm

      There is no gas in my part of rural Devon. Everybody I know has an oil-boiler and a woodburner, there being a near-infinite supply of wood.

    • November 21, 2020 4:19 pm

      Sadly the present direction of travel in UK energy policy is towards dystopia, not utopia.

    • H Davis permalink
      November 21, 2020 6:44 pm

      Half of the failures we’ve had involve a bad motor capacitor. Even under warranty it cost $150 to replace the latest failed Chinese capacitor. A capacitor failure is suggested by either the outside fan humming but not turning or the fan runs but the compressor fails to start and may also hum. This mode is harder to detect since the running fan makes it seem that the unit is running normally. Listen carefully to see if the compressor is running. Check if there is room temperature air coming out of the registers indicating the compressor is not running. A compressor that fails to start may also trip the breaker but not always. Don’t let the system run if the compressor fails to start as it will damage the compressor motor.

      If you’re handy open the cover on your outdoor unit (after turning it off at the breaker) and get the numbers off the capacitor. It should say something like 50 uf or possibly 5/50 uf if it’s a dual capacitor for the compressor and the fan. There may be a separate capacitor for the compressor and the fan. There should also be a voltage number. Here in the states with 240 volt compressors the voltage rating on the capacitors will be something like 377 to 400 volts. Also get the exact part number off the capacitor and note its dimensions since these things come in lots of different physical sizes. Having a replacement that will fit in the same mounting as the original makes for easy replacement.

      Go to Amazon and buy a non-Chinese made replacement. There are dozens available. Here in the states they cost less that $20. Have it on hand when next your system goes belly up. There’s a good chance you can fix the next failure yourself. And you won’t have to go without heat/cool while waiting for the repair man.

      There are lots of videos on YouTube showing how to replace a capacitor.

      H Davis

      • Duker permalink
        November 21, 2020 7:35 pm

        Isnt the US domestic voltage 110 V ?
        Not sure why you need capacitors.

      • In the Real World permalink
        November 22, 2020 10:05 am

        Duker , the capacitor on a single phase AC motor is to put one set of windings ” out of step ” to give it its direction of rotation .

  21. Ben Vorlich permalink
    November 21, 2020 3:37 pm

    This may be relevant.

    The prime minister’s pledge to ban gas boilers from new homes by 2023 has been withdrawn.

    The promise first appeared on the Downing Street website this week attached to Mr Johnson’s climate plan.

    But the date was later amended, with the PM’s office claiming a “mix-up”.

    The original statement from Number 10 announced this goal; “2023 – Implement a Future Homes Standard for new homes, with low carbon heating and world-leading levels of energy efficiency.”

    That means no room for gas central heating, which is a major contributor to the emissions over-heating the climate.

  22. MrGrimNasty permalink
    November 21, 2020 3:48 pm

    You can see it now, UK has had a laying snowfall, high pressure moves in from east, this allows widespread night temperatures of -10 to -20C as happened repeatedly in 3 or so 1980s winters, windmills are becalmed nationwide, everyone with an ASHP turns on electric heaters……….

    If that doesn’t make you cry, this will.

  23. Ray Sanders permalink
    November 21, 2020 3:52 pm

    There is an overlooked problem with air source heat pumps relating to their CoP. The ratio drops as the temperature falls so at a balmy 15°C you may get a ratio of 1 in for 3 out, as you drop to 0°C air temperature the ratio falls to below 1 in for 2 out and at -18°C you might as well just use a resistance heater. However, the ASHP will probably have stopped working at about 5°C below freezing to protect itself from damage. So this creates a massive problem for the electricity supply in that a sudden drop in temperature such as an easterly cold front hitting the south east just as the sun sets on a weekday and demand will skyrocket in minutes.

  24. November 21, 2020 3:55 pm

    I had a new gas boiler installed a few weeks ago and the house is warm and the water hot. It cost £1500 including installation. Can someone tell me why in 10 years when I am thinking of replacing it, I will have to spend 4x as much for the ‘benefits’ of a cold house and a tepid shower? To compound the stupidity these measures are based upon a myth that any person with a modicum of common sense would know was erroneous!

    • Tym fern permalink
      November 21, 2020 7:08 pm

      Why replace in 10 years? They last much longer.

      • Mad Mike permalink
        November 22, 2020 12:54 pm

        I installed 2 Vaillant boilers in 2004. They are still going strong with minimal maintenance. They were expensive at the time but you know what they say about buying cheap.

  25. Dave Ward permalink
    November 21, 2020 4:19 pm

    “There are more complex solutions to supplying hot water”

    Strikes me that a good old fashioned indirect hot water tank and 2-3kW immersion heater would be the simplest. The coil would heat the contents up to whatever the Heat Pump could manage, using the radiator circuit and standard 2/3 port motorised valves, then electricity “Tops Up” to a satisfactory (and Legionella safe) level. This means you have a degree of redundancy – you’ll still be able to have a shower/bath if the Heat Pump fails. Always assuming the grid hasn’t collapsed, or your “Smart Meter” cuts you off…

  26. Nancy & John Hultquist permalink
    November 21, 2020 4:21 pm

    We live in a low cost electric region – central Washington State with hydropower. The house was built in 1982 as an all-electric with internal ducts to every room. Winter temperature will get to well below freezing; -20°C. The compressors (the heat pump parts) are outside. Search-up ‘train heat pumps’ using an images tab to see such things. They are large and boxy, as is the inside unit – the air handler.
    The interesting temperature is about freezing to 4°C, at which point the air is too cold for the heat pump to efficiently provide house warming heat. Our whole-house forced-air system is an inside “air handler” with a fan, filters, and resistance heaters.
    I built a concrete stand to hold our outside unit about 60 cm up from ground level – above most snow depth, and where male dogs can reach.
    Except when cold temperature comes and the system switches to “resistance” heat, this is a good system for us. Sum of reasons: single family house, well insulated, built with ducts and space for air handler, and low cost electricity. The current unit has been installed for 15 years. Neighbors heat with propane, delivered to a large tank in their yard. Search-up ‘painted propane tanks’ with images for a few moments of hilarity.
    A last thought: Our electricity has never been off for more than 4 hours – but it could! Thus, we also have an efficient modern wood stove for emergency. My wife has medical issues so that we do not use wood on a regular basis, although that would reduce costs some.

    • Dave Ward permalink
      November 21, 2020 5:44 pm

      “Search-up ‘painted propane tanks’ with images for a few moments of hilarity”

      Brilliant! Particularly the giant “Marrow” ones. I’ve never seen anything like that in the UK – I suspect that’s due to the tanks being owned and rented from the gas supplier. Are they are normally privately owned in the US?

      • Nancy & John Hultquist permalink
        November 21, 2020 8:15 pm

        Either way. The painted ones may be owned as you suggest. The local supplier near me uses white or a dull green, with a big logo on the side.
        Where there are multiple suppliers, owning the tank allows you to switch over service or costs, but comes with more responsibilites.

    • Paul H permalink
      November 21, 2020 9:24 pm

      Not too sure what you are trying to say here.are you condemning heat pump solutions or promoting them?

  27. GeoffB permalink
    November 21, 2020 4:21 pm

    My daughter had an ASHP in her purchased apartment in Washington DC. It is a 25 year old complex of about 50 apartments, each one with its own ASHP located on the flat roof, its just air conditioning, no water involved. In summer it cools, in winter it heats, but needs resistive heating at low temperatures, to stop the unit on the roof freezing up as well as resistive heating in the room units. It failed miserably to heat the apartment and the electricity bill is astronomical, the other problem is reliability and the cost of servicing, they had to pay for a street closure and medium size crane to replace the outside unit… They have moved to a rented apartment with water radiators and a central boiler house.

    • Duker permalink
      November 21, 2020 7:32 pm

      Sounds like a very old unit. Modern ones use ‘inverter technology’- a fancy word for DC motors and fans which have variable speeds- which is much more efficient.
      it best works in more temperate areas but would be great for Washingtons hot humid summers, not so good for the colder winters where snow is common.

  28. Colin Megson permalink
    November 21, 2020 5:31 pm

    I think you need COP 3 on the ‘8 kW as the norm’ figure you selected, which take s the 200 GW of installed capacity down to 67 GW.

    I wonder if you would consider a bit of ‘economics’ research on domestic scale FCCHP units. Green hydrogen will replace natural gas by 2050, but I would not have hydrogen piped inside of my house, as it does not have a roof that “…can be safely blown away from the rest of the structure in an explosion…” (see Wikipedia’s ‘Hydrogen safety’ page).

    I wouldn’t mind hydrogen piped up to an outside FCCHP unit and many houses selling their electricity back to the National Grid might not only prove economically sound for the occupants, but also cut down on electricity T & D infrastructure spend.

    • November 21, 2020 7:30 pm

      Yes, thanks Colin, you are right

      The 8KW is the output – I read it as input! I’ll add a correction

      Hopefully your green hydrogen will be as cheap as our natural gas is!

  29. Beagle permalink
    November 21, 2020 6:16 pm

    The best option would be to have a hybrid boiler using Natural Gas and backed up with an ASHP. The gas would heat the water quickly and then the ASHP would maintain the base temperature and the gas topping it up when needed. To just rely on an ASHP to heat the radiators you would need much bigger radiators circulating the luke-warm water.

    • Ben Vorlich permalink
      November 21, 2020 6:47 pm

      Why have two systems, particularly when one is more expensive than the other and doesn’t do the job. Paying off the additional system using cost savings, if they even are there which seems doubtful, will take longer than the life of the system. It’s like having a car with two propulsion systems one which will take you to work but not home again, and the other gets you there and back.

      Please explain the rational

      • Harry Passfield permalink
        November 21, 2020 8:21 pm

        Plus ONE

  30. HuwT permalink
    November 21, 2020 7:15 pm

    Candidly, if this green nightmare looks like it might become a reality then we need to take to the streets!!!

    • Paul H permalink
      November 21, 2020 9:48 pm

      Oh dear, the antidote to the madness. Glad I didn’t say that. Just speculation of course, but how else is it possible to reverse the Green Blob without severe physical prejudice? There are no meeting of minds, no compromises- not that compromises are a solution-nothing that suggests a common ground because there is no common ground. It’s us or them, total warfare. How we preserve our way of life is becoming problematical. Either we say enough is enough or we’ll be fighting a rearguard action until reality kicks in, at which point all of us are in deep doo doo, and to be really pessimistic, it will be dog eat dog. What a legacy we will leave our progeny. Freedom is not free, it has to fought for. We keyboard warriors have to devise a strategy-and fast.

  31. November 21, 2020 8:11 pm

    Reading through all the comments, if heat pumps are to work effectively we will surely need triple glazed window units as standard , rather than double glazed. Don’t know what that would add to the costs of a house

    • Adam Gallon permalink
      November 21, 2020 8:44 pm

      Your local Everest rep here, triple adds under 10% to the cost of windows. So maybe 1 or 2% increase in the cost of a house.

      • November 21, 2020 9:02 pm

        So that could be £5000 or so on a modest house in the south? Quite significant and I’m not sure the extra cost would ever be repaid in heating savings although the house would be at a more comfortable temperature.

        How much better is triple glazing at heat retention than double glazing! as the latter stubbornly remains the norm.

      • Nancy & John Hultquist permalink
        November 22, 2020 3:02 am

        A few years ago the sliding glass door to our backyard needed replaced. A nearby dealer of such things carried Pella® windows and doors.

        The company has many products. We went with a door that has a gas (Argon, I think) between the layers of glass, and a reflecting coating.
        The following site:

        … has a heading: “Spectrally Selective Coatings”

        Interesting technology, and expensive.
        I’ve no idea what is available elsewhere, but Adam’s Everest seem to carry similar things.

  32. David permalink
    November 21, 2020 8:49 pm

    It seems to me that heat pumps of the sizes suggested for homes will sort of work when outside temperatures for a UK winter are about average, maybe 8 deg but as soon as it gets below freezing people will be shivering without supplementary heating.

  33. November 21, 2020 10:03 pm

    The answer is obvious to me.
    We should defer the conversion to Heat Pumps for 500 years.
    By then the Climate will have warmed up by 5C and they will better handle the warmer winter temperatures then.

  34. Graeme No.3 permalink
    November 22, 2020 4:23 am

    One of the problems is too many lawyers in government; they think that passing a law means that something will happen, and can never be convinced that it is impossible through complete ignorance of technical matters. As one Greenie put it “if you wish hard enough it will happen”.
    The problem is exacerbated when public servants get involved and don’t consider that matters might be interrelated or dealt with by another Department; thus policy is based on the assumptions that…
    Renewables are emission free
    Renewables are cheap
    Adequate generation by Renewables is just a matter of installing more wind turbines.
    Electric cars can be used as backup to charge the grid when necessary.
    All electric dwellings will lower emissions.
    Hydrogen can replace natural gas because it doesn’t emit CO2 and it will be cheaper because renewables are cheap and plentiful at all times.
    Heat pumps generate 4 or 6 times the benefit of their electricity use.

    The result will be blackouts, steeply rising electricity costs and The Secnd Peasants Revolt.

    • Gerry, England permalink
      November 22, 2020 1:57 pm

      The main problem is too many stupid people in government at all levels. I know, I work with lots of morons at my council. Today’s Mail looks at the idiocy of all the (empty) cycle lanes that have been put in with no consultation. To that you can also add all the empty extended footways put in across London. And the latest scheme is to take away paid parking and put in (empty) bicycle bays at a time when the council is struggling for money. The bays are full of vans providing services and income. And if that wasn’t enough, they have unveiled a climate plan that will cost millions.

  35. Tim C permalink
    November 22, 2020 7:59 am

    The easiest and cheapest solution will soon be a diesel generator

  36. Looking to Learn permalink
    November 22, 2020 11:47 am

    Are there any good books along the lines of this blog?

    I’ve always known this whole “crisis” is manufactured nonsense, mainly due to common sense, but I wouldn’t really be able to argue it because I’m not informed enough, so any “must read book” recommendations would be great. Thanks.

    • Harry Passfield permalink
      November 22, 2020 5:14 pm

      Andrew Montford’s book, the Hockey Stick Illusion. A good start.

      • Looking to Learn permalink
        November 22, 2020 6:46 pm

        Thanks a lot, that looks perfect.

    • Malcolm Chapman permalink
      November 23, 2020 5:51 pm

      Harry’s suggestion is a good one – I bought Montford’s book for a couple of my alarmed friends, but it is bit too focused on the Al Gore propaganda piece, and of its time in other ways. Perhaps we could add the three volumes called ‘Climate Change – The Facts’ (dated, from memory, 2010, 2017 and 2020, various editors; not to be confused with a BBC programme of the same name), or the recent volume by Michael Shellenberger, ‘Apocalypse Never’; this last bows to the CO2 causes warming idea, which most here do not, but is clear that renewable energy is almost entirely a scam.

  37. Mike Jackson permalink
    November 22, 2020 1:43 pm

    Meanwhile in other, related, news this morning …
    The Telegraph tells us that “ Nuclear fusion could be a reality within 20 years”.
    What, again? Or is it still?

    • Gamecock permalink
      November 23, 2020 3:18 pm

      Propaganda to get people to believe change is possible. To displace the public’s common sense.

  38. November 22, 2020 3:47 pm


    Unlike most people, I can tell you something of substance, since I actually have 6 ASHPs, so I have first hand actual experience of air sourced heat pumps, and my neighbour in addition has an air to water heat pump with under floor heating.

    The first point is that I have a detached property with about 140 sq m of living area, so about 1,500 sq feet. I have 28KW of output, not 8KW. An 8 KW ASHP is advertised as being suitable for rooms of about 40sq m, say about 430 to 500 sq feet. An average UK house is about 1,000 sq ft, so it will need a minimum of about 16KW output, not 8 KW. So that alone doubles your figures. Thus theoretically, my 1,500 sq m villa could perhaps get away with 24KW, but I do not consider that I have over capacity at 28KW. That said, I cannot run all my aircons at the same time, but that is because the power input into my villa is only 40 amps, and with other domestic appliances and swimming pool pump, that causes the main fuse to flip!!

    Second, I have checked the EU certification for my unit. It is EU certified at SEER 8.7 (cooling), SCOP 6.2 (heating). The unit is a Daikin which are expensive, but have about the best reputation for quality and reliability on the market. I have no reason to believe that the EU certification is bogus, given the good reputation of Daikin.

    Somewhere I have the real data sheet that specifies the ambient temperature at which the SEER and SCOP figures are assessed. Of course, these are only an assessment, and are only as good as the assumptions on which they are based. Southern Spain is warmer than the UK, so in the UK, the ASHP will not have as good performance.

    One of the big issues here is that there is a world of difference between Scotland and the south coast of England. What is feasible in the south, is probably a non starter in Scotland, and it would appear that the UK Government has not considered that sufficiently.

    Finally, I would say that aircon units are very reliable. Apart from gas leakage over time, I have had no problems whatsoever in 20 years, and the unit I replaced last year (a Mitsubishi), had been in service since 1985, and was working perfectly, it only reuired re gassing, but it used a prohibited gas, so had to be scrapped, rather than re-gassed. Of coursde, it was an old fashioned design, and not the more efficient inverter design.

    • November 22, 2020 4:24 pm


      Down here in Torbay we would reckon on day time temps in the winter to regularly reach 10centigrade, sometimes much more, , with a night temperature of around5 degrees centigrade. Frosts are rare as is snow but they can happen.

      Can I ask how much all your 6 heat pumps cost? It sounds very expensive to have so many separate units as opposed to say a single gas boiler.

      Also, do you have any other sort of ancillary heating or are the pumps always warm enough?

      • November 23, 2020 10:21 am

        It is Spain, on the hill side close to the Med. I have electric underfloor heating in the bathroom and en suite. That is just like an electric blanket on which the floor tiles are laid. The ASHP provide all the heating and cooling, although I have a log fire in one of the lounges which I use frequently, in December and January, because of the cosy atmosphere, and because the wood is free. I do not need the fire (which is in build with twin fans blowing out hot air) to add supplemental heating, and when I use it, I do not need to use the aircon. Of course properties in Spain are not well insulated, and have higher ceilings.

        Last night the night time temperature was 13 degC (say through to about midnight), about 5 days ago it was 19 degC (when we had an unusually warm day of 28degC). In winter there are only about 5 to 10 days where night time temps drop below 8 degC. In 20 years there has never been snow in the foothills, but a few times there has been on the top of the mountain further in land, where it rises to around 1,100 metres.

        A small cheap ASHP suitable for a bedroom (say about 2.5 to 3.3 KW) costs about €300. Better quality €500/€600. A cheap ASHP suitable for a lounge (say about 5KW) about €500, better quality about €1,000. A large unit of about 8KW say between €800 to €1700. Modern designer units between about €1,400 and €3,000 each.

        Of course a large unit of around 8KW could be used to heat/cool 2 rooms and this costs more because you need a second indoor unit and trunk/piping. Installation is also considerably more.

        Standard installation is about €200 per unit, but no doubt if you were fitting several a deal could probably be struck. It may cost more in the UK since scaffolding is probably required to fit in the upstairs of a house.

        Having individual units for each room is easier for installation (provided that the property is detached) and is more flexible, being used only when you want it.

        If one had to compare the costs of fitting radiators and a boiler, it is probably similar to fitting 5 or 6 ASHPs. Of course, gas is presently far cheaper than electricity.

        As regards climate, at a guess the temperature in Southern Spain is about 4 to 6 degC warmer than Torbay. The Med is far warmer than the seas off the coast of England, and that leads to a mild winter. In December we would expect many days of about 20degC, with one or two days of around 22/23 degC, but typically 16 to 18 degC. This month every day has been over 20degC, except the last 2 days.

        Modern ASHPs are relatively quiet. The indoor unit has a quiet mode of about 17db, but typically somewhere between 21 to 27db, the outdoor unit is around 42 to 48db. The indoor unit is essentially a fan heater so you expect to have some noise, but it is not excessive.

    • Harry Passfield permalink
      November 22, 2020 5:16 pm

      Richard: Is this in Spain?

  39. November 22, 2020 4:13 pm

    In winter the East coast of England is also cold.
    Maidstone, Kent has a mean low temperature of 2C in January, same as Glasgow.

  40. Hot Potato permalink
    November 22, 2020 4:26 pm

    Costings need not be as bad as you say. In France we can buy 2 off 2.8 KW units – drawing about 750 watts (COP 4) each for 1000€ delivered. These are DIY installable with units and pipes pre gassed. They act as air con in summer and heat in Summer. We have them in bedrooms. Winters can be just as cold as England – but shorter. I agree with your main thrust on Grid capacity, the problem could be alleviated by Rolls Royce city sized nuclear units. The Global warmers always omit the Solar variance. Just as the high level of Solar activity in the latter half of C20 caused most of the temperature increase, the low level of Solar Activity for the next 30 years is going to cause a temperature decrease.

    • November 22, 2020 6:59 pm

      I believe your electricity prices are much cheaper than here – not sure about gas though.

      I presume you have stand alone units in each room? Obviously that will lower installation cost, but would not be acceptable here, where people want central heating.

      • November 23, 2020 10:24 am

        Electricity prices in Spain are higher than UK. Maybe because the VAT is more.

    • November 23, 2020 10:44 am

      In Spain, that sort of unit (cheap make) can be bought for about €300 each, €500 fitted included. Often you see ads for €450 including fitting. Perfect for a bedroom.

      Whilst the main units are pre-gased, I have never seen the pipes being pre-gased. I have seen many instalations, and they use a vacumn pump to extract the air in the piping, some then flush with Nitogen, and repeat, before opening the valves on the pre gassed unit. The gas in the pre gassed unit then fills the pipes with the gas.

      Installation is not that complex, but without the vacumn pump, it cannot be done by the handy DIYer.

  41. Bertie permalink
    November 22, 2020 5:01 pm

    i don’t even know what a heat pump is or how it works. However, I am happy to go back to log fires and horse-driven transport.

    • Joe Public permalink
      November 22, 2020 6:16 pm

      “I don’t even know what a heat pump is or how it works.”

      Have you got a refrigerator? If so you own/use a heat pump.

      A HP moves heat from one place to another. In the case of a fridge – from inside the cabinet to outside the cabinet.

      Hence, if you’re feeling cold in your kitchen, open the fridge door! 😉

    • Stuart Brown permalink
      November 22, 2020 8:11 pm

      There are 850,000 horses in the UK. Let’s say half a million are mares. They could have 16 foals in their lifetime and only produce one foal per year. Will there be enough horses by 2035 one might ask? I leave the maths to others because I am drowning my sorrows at the stupidity of it all.

      • Gamecock permalink
        November 23, 2020 3:19 pm

        The Colonies will bail you out. Again.

  42. Dave Cowdell permalink
    November 23, 2020 3:18 pm

    My Welsh farmhouse with 3 foot thick stone walls and conventional radiators came with twin 12 kW ASHP units, cost a fortune to run with the added disadvantage that the house was freezing in the winter. Add to that, the original manufacturer in China no longer exists, the importer has disappeared, and the installer has gone bankrupt. A fault on the PCB means that no one can fix since all ” heat pump specialists” are really plumbers on disguise.
    Bye bye ASHP unit and replaced by an oil boiler, result manageable bills, toasty house and boodles of hot water.

    • Paul H permalink
      November 23, 2020 4:16 pm

      Dave, it’s perhaps a bit late for you but there are companies that repair PCBs. I’ve had one done for a dishwasher and one for a cooker hood. Both successful and a pal had one done for a telly.

      • Dave Cowdell permalink
        November 24, 2020 10:32 am

        All gone to the big recycler!

Comments are closed.

%d bloggers like this: