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Heat pump costs soar because Britain’s radiators are ‘too small’

May 17, 2022

By Paul Homewood




Homeowners trying to install eco-friendly heat pumps have been left with surprise £30,000 bills after it emerged millions of radiators are too small to work with the new technology.

The Government wants 600,000 heat pumps installed every year by 2028, in line with its “net zero” aims, but the majority of homes may need thousands of pounds worth of upgrades to accommodate them.

Heat pumps need larger radiators to achieve the same heat output as gas boilers, which heat water to much higher temperatures.

Some 99pc of British homes do not have radiators large enough to heat a room on the coldest winter’s day, using a low-temperature heat pump, the most common model, according to a Department for Business, Energy & Industrial Strategy study. "High temperature" heat pumps can help fix this but 90pc of homes would still need better radiators.

To heat a home on an average winter’s day, 94pc of British households would need to upgrade their radiators if using a standard heat pump.

Gas boilers achieve temperatures of around 70°C, but most air source heat pumps operate at around 35°C to 45°C for the radiator system and around 55°C for hot water.

The Department said the typical costs for buying compatible radiators would be £1,700 for a one to two-bedroom house, £2,200 for a three-bedroom house, and approximately £2,900 for a five-bedroom house. However, this does not include the labour cost of fitting a new heating system.

Some customers have been hit with much higher bills. Michael York, 83, was quoted nearly £30,000 to install a heat pump and replace all his radiators.

Mr York said: "Last year my 19-year-old boiler was making a funny noise and I decided it was time for an upgrade. I looked into a heat pump, because of the Government’s interest in them.

"I consulted a heat pump specialist who said the installation cost for a suitable heat pump and changing all the radiators was nearly £30,000. My house was built in 1976, it’s detached, it has cavity wall insulation, and double glazing. It’s very well insulated."

Mr York said the specialist told him there were several rooms in his home that would not be able to accommodate radiators large enough to achieve the same heat output as his gas boiler. "The prices have come down and it would now cost around £20,000, but I didn’t want to spend that when I could just pay £2,400 for a new gas boiler."

Andy Kerr of Boxt, a gas boiler retailer, said: "Most houses that have a heat pump installation will need to have at least one radiator replaced.

"Heat pumps also require a water storage tank, which many properties no longer have due to the popularity of combi boilers. It is a complex installation and usually requires the whole central heating system to be replaced."

A spokesman for BEIS said: "Gas boilers are expensive to run, whereas electric heat pumps are more efficient. Anyone who chooses to install a heat pump can claim a grant worth up to £5,000 and ​will also benefit from 0pc VAT.  

“We are working with industry to further bring down the cost of heat pumps by up to half by 2025 as the technology develops, making them ultimately the most affordable and sensible option.”


I notice BEIS are still misleading about running costs. Despite recent gas price rises, heat pumps remain more expensive to run for most homes.

The comment about the water storage tank is also relevant, as many homeowners have long got rid of them, in order to make room for cupboards and so on.

And all BEIS can come up with is a taxpayer funded grant and zero VAT subsidy. Who on earth do they think will pay for these when we all have to install one?

  1. Martin Brumby permalink
    May 17, 2022 10:25 am

    “Eco-friendly” is a convenient shibboleth for someone being eco-nomical with the truth.

    BEIS want sacking as part of Boris’s alleged plan to slash ‘Civil Servants’, (itself an oxymoron.)

    • Mike Jackson permalink
      May 17, 2022 3:06 pm

      My experience of dealing with ‘eco-people’ over the years is that ‘economical with the actualité’ is very much second nature. Rather like some others recently in the headlines facts are what they would like them to be and hissy fits follow if you don’t immediately agree with them 100%. The fallback position, of course, is always “we need to do it anyway to save the planet”.
      Shades of “it was necessary to destroy the village to save it”!

      • Duker permalink
        May 18, 2022 3:13 am

        This is an installer talking about how it really is
        ‘Modern Gas condensing boilers have very slow flow and very high temperatures. They deliver the water to the radiators at about 70 degrees C let it hang around in the radiators for quite a long time so it falls to 50 degrees C, before it returns to the boiler for re heating.

        In Old boilers the flow rate was faster but still with very high temperatures. They delivered the water to the radiators at about 70 degrees C let it hang around for a short time so it falls to 60 degrees C before it returns to the boiler for re heating.

        And finally in heat pumps we have very fast flow rates but medium temperatures. They deliver the water to the radiators at about 52 degrees C, we let it hang around in the radiators for a few seconds, so it falls to 47 degrees C before it returns to the heat pump for re heating.”
        it seems that most rooms will be fine, some places might need an extra radiator and the tubing that goes with it.
        I see in existing homes they can have those large sized radiators that go all the way up the wall when the wall space is limited
        Not that its a great idea for many to change from gas to ASHP

      • catweazle666 permalink
        May 18, 2022 2:14 pm

        “This is an installer talking about how it really is”

        No, it really isn’t!

      • Duker permalink
        May 18, 2022 10:56 pm

        Hes a system designer at an company that installs systems , 1000s so far.
        His methods and advice seem completely valid.
        Are you a radiator heating expert yourself ? Or just ‘a critic’

      • catweazle666 permalink
        May 19, 2022 12:31 am

        “Are you a radiator heating expert yourself ? Or just ‘a critic’”

        In fact I’m a retired engineer with an in-depth knowledge of physics and thermodynamics and the capabilities of the systems that are dependent on such knowledge going back around half a century.

        I have also a fair amount of hands on experience of renovating centuries old old properties, including plumbing, wiring, gas (my certifications are acceptable to the relevant authorities to sign off installations of both) and specifications of such equipment.

        But in this case, that is pretty much irrelevant, I don’t need to be a cowboy to recognise the smell of bullshit.

    • Ray Sanders permalink
      May 18, 2022 8:57 am

      In response to Duker….the linked in article you have referred to is quoting pure bollocks. The thermal handling capacity of pipework is determined by the pipe diameter, length of run and most importantly the water velocity – the faster the flow the greater the friction. By claiming higher flow for heat pumps he is defeating his own absurd argument. However “friction” is nothing to the “fiction” he is also writing “we have just sold our 10,000th heat pump so we are getting good at this now” Really? For a company set up in 2018 and now filing dormant accounts that is somewhat improbable. I doubt there is any UK based supplier that has ever managed that number let alone this chancer.
      This type of thing is typical of this next generation double glazing salesmen.

      • Ray Sanders permalink
        May 18, 2022 9:11 am

        Looking further I notice he claims elsewhere to have “designed 10,000 heat pump installations in 15 years” So has he “sold 10,000” or not? And what a busy bee he is allegedly “designing” 3 systems for every single working of the last 15 years?
        A classic example of why in a few years time people will be trying to claim compensation for mis sold heat pump instalations.

      • Duker permalink
        May 18, 2022 11:12 pm

        And the actual advice on which room size will be Ok with existing radiators and those that will require a additional radiator ( or a larger one) is technically valid or not?
        Yes, his experience seems be based on the manufacturers sales for which they ‘wrote the install guide’ rather than those that crossed his desk.
        ‘ Samsung asked us to launch their air to water heat pumps in the UK. We started from scratch and quite literally wrote the book (and the training) on Samsung air to water heat pump systems.’
        I assuming the Samsung have dozens of installers
        Yes theres a certain amount of job puffery thats common on Linkedin so not to be taken literally which you have done ( but you dont dispute his technical advice)

        For some people it does make sense to use heat pumps. Not all existing gas based systems would be feasible to convert but the actual savings in running costs are real
        I bought a new fridge 6 months ago which uses heat pump technology , it was mainly for the quietness compared to the normal fridge on off cycle. But the lower power cost is noticeable as well

      • catweazle666 permalink
        May 19, 2022 12:47 am

        “I bought a new fridge 6 months ago which uses heat pump technology”

        I would be interested to see a fridge that doesn’t rely on heat pump technology!

        As a matter of interest, I’m surprised that little attention is paid to the old gas heat pump technology as found in the gas fridges that were (still are?) once widespread, especially in caravans and the like, with no moving parts whatsoever which relied on a flame not much bigger than that of a cigarette lighter to provide the energy to drive the process, often backed up with an electric heating element for use when the vehicle is in motion.

        I have also played with Peltier thermo-electric devices, the efficiency isn’t that high however.

        This I consider could be adapted for use as air conditioning system in sunny countries where electricity isn’t available.

      • Duker permalink
        May 19, 2022 2:47 am

        Still no disagreement with his actual technical details he provides then ?
        From his table tell me how many of your rooms need more radiators ?
        Or is it modern sorcery which you wont have a bar of alongside that other evil- double glazing

        I mean modern heat pump technology which uses DC or inverters as they call it

      • Ray Sanders permalink
        May 21, 2022 1:12 pm

        n further response to Duker, the table in the blog is pure, unmitigated BS designed to fool the gullible. It gives no evidence other than the poster’s “opinion”….to paraphrase Mandy Rice Davies ” Well he would say that wouldn’t he”

  2. steve permalink
    May 17, 2022 10:41 am

    My house along with many others built in the 80’s and 90’s is fitted with 8mm micro bore copper piping which is completely useless with a heat pump. All the copper piping would need replacing which means either new pipes fitted on the plaster board or ripping out the plaster board and fitting underneath new plasterboard. My gas boiler is 32 years old and so far has never let me down. I am seriously considering putting in a new gas boiler before they are banned by this idiotic green nonsense.

    • JBW permalink
      May 17, 2022 11:12 am

      A few years ago we upgraded our gas boiler, as it was difficult getting parts for our 25 year old one. As our installer said at the time, the new boiler is more efficient than the old one, but probably won’t last as long.

  3. Athelstan. permalink
    May 17, 2022 10:45 am

    I cannot quite get my head around the eejits in the beis (or bunter for that matter) thinking that 600 thousand people per year are going to install inferior and more expensive CH kit, whose more bonkers? Heat pumps, you’d have to be mad. Ah but then, the carbon zero delusion is all based on madness and political space cadet’s mythologizing.

  4. Brian Smith permalink
    May 17, 2022 11:06 am

    You also need to factor re-decorating costs into your calculations. If you want to be honest, that is.

    Where I live, an average sized room costs about £1,000 to re-decorate using a tradesman, less, obviously, if you can do it yourself.

    But when it comes to DiY, we need to remember we are talking about every room and passageway in the house. A prospect even the most ardent DiY person might baulk at.

    • teaef permalink
      May 17, 2022 10:17 pm

      £1000 for one room, must be gold leaf emulsion paint!

      • Russ Wood permalink
        May 19, 2022 2:08 pm

        Nope – We got our house repainted before we sold it, after 32 years of living – with the ORIGINAL high-quality paint job we started with as we moved in. It took a team of 4 painters over a week. First to prepare and fill little cracks, then the actual two coats. Not going to give prices as there is no real comparison between Rands 10 years ago and pounds now. So maybe 1000 pounds a room is OK!

  5. Mikehig permalink
    May 17, 2022 11:10 am

    “We are working with industry to further bring down the cost of heat pumps by up to half by 2025 as the technology develops, making them ultimately the most affordable and sensible option.”

    Heat pumps are a mature technology with many millions installed all around the world. It may be that costs in the UK are inflated due to lack of cognisant and qualified suppliers and installers so there might be some savings to be had with scaling up.
    Perhaps someone with knowledge of costs in other countries could comment?

  6. Gerry, England permalink
    May 17, 2022 11:39 am

    A spokesman for BEIS said: “Gas boilers are expensive to run, whereas electric heat pumps are more efficient.”

    Well, there is a lie front and centre. But given the PM is a proven serial liar why be surprised when the government he leads follows suit. And with news today that electricity prices will rise every 3 months the cost of running a heat pump will just keep on growing.

    • Chaswarnertoo permalink
      May 17, 2022 5:19 pm

      More efficient may be true. A LOT more expensive than a gas boiler is also true.

      • catweazle666 permalink
        May 17, 2022 7:17 pm

        Who on Earth ever thought converting natural gas (or coal!) into electricity, dispatching it via the grid and several transformers and then running a heat pump with it is entirely scientifically illiterate or dangerously mendacious, most likely both.

      • catweazle666 permalink
        May 17, 2022 7:18 pm

        Forgot to put “efficient” in there somewhere!

      • Duker permalink
        May 19, 2022 2:33 am

        You seem to be technically illiterate about heat pumps. A household ‘system’ may not be the be all for existing houses but theres no doubt about the efficiency and performance.
        I have 2 plus a fridge which has similar tech

      • catweazle666 permalink
        May 21, 2022 7:17 pm

        “You seem to be technically illiterate about heat pumps.”

        Actually sunshine, as I have been responsible for heat pump installations on industrial refrigeration plant, I rather think that’s you.

        Now go away and stop making a total fool of yourself!

  7. May 17, 2022 11:40 am

    The problem has been an obvious one for anyone with the even a basic knowledge of water based central heating. A boiler works at a high flow temperature of around 70-80°C, but an air source heat pump operates at a lower temperature. For an ASHP, it’s around 35°C to 45°C for the radiator system and around 55°C for hot water. This is aside from the pipe sizing etc. How do they get away with it?

  8. Harry Passfield permalink
    May 17, 2022 11:48 am

    “A spokesman for BEIS said lied: “Gas boilers are expensive to run, whereas electric heat pumps are more efficient”.”

    • Brian Smith permalink
      May 17, 2022 11:52 am

      Yes, compares apples with pears. Careful use of language gives a totally dishonest representation of the reality of heat pump technology.

      • Joe Public permalink
        May 17, 2022 5:33 pm


  9. Joe Public permalink
    May 17, 2022 12:00 pm

    The “Heat pump costs soar because Britain’s radiators are ‘too small’ ” claim is a load of bollocks.

    Heat pump costs soar because Britain’s radiators are correctly sized to match the performances of swift response boilers that minimise energy consumption by needing minimal pre-heat periods.

    Any undersized heat source (heat pump or replacement boiler) will underperform if bolted to a system it wasn’t sized for!

    The other crucial aspect is that for the past 2-3 decades, much of the pipework feeding radiators from a boiler is in compact micro-bore tubing, and few heat pumps are capable of meeting the water-flow requirements at the desired flow/return temperatures.

    A replacement 25kW combi boiler that serves both space heating AND domestic hot water can cost under £600 inc VAT

  10. TrevorC permalink
    May 17, 2022 12:07 pm

    Heat pumps may be a ‘mature technology’ around the world, but most(all?) of these are heat pumps that produce hot air, not hot water for radiators. They may be simple units that fit high up on a wall in each room, similar to an air conditioner, or the air may be fed into an existing ducted heating system (I think this is typical in the US). They are not the same as the expensive, radiator systems being peddled by the UK government.

    • Beagle permalink
      May 17, 2022 12:54 pm

      Yes Trevor heat pumps are usually used for underfloor heating or blown air. I don’t know any country that uses a heat pump to heat radiators and is efficient and not having a secondary source of heat.

    • M E permalink
      May 18, 2022 4:47 am

      Yes,in New Zealand a heat pump is outside the housing unit and is supposed to take heat from the air to an inside fan unit high on a wall , where it can be manipulated on/off and to suitable temperatures with a remote something like a T V remote.
      They are not satisfactory when the weather is very cold. I don,t use the one here.

      • Duker permalink
        May 19, 2022 2:39 am

        How much of the year is ‘very cold’. 5C or below ? Doesnt mean it cant be used for the maybe 10 other months of the year.
        In some very cold overnight places ( that dont have gas) it might be best to leave on all the time and at its minimum setting of 16 or 17C. That way its still efficent, avoids the icing up and only needs localised extra radiative heating in the rooms being used.

  11. Philip Mulholland permalink
    May 17, 2022 12:23 pm

    Some 99pc of British homes do not have radiators large enough to heat a room on the coldest winter’s day, using a low-temperature heat pump

    A mere engineering detail.
    What has this got to do with Policy?

  12. William George permalink
    May 17, 2022 1:17 pm

    The BEIS should be scrapped along with Deben and the CCA. Both are contemptible liars.

  13. RichardW permalink
    May 17, 2022 1:24 pm

    Here’s a vid of what might be involved in a heat pump retro fit – at 0:30 some idea of the size of the outside unit, and at 10:35 some idea of the unobtrusive rads you might have to fit in some rooms !!

  14. catweazle666 permalink
    May 17, 2022 4:01 pm

    In a word – USELESS!

  15. T Walker permalink
    May 17, 2022 6:27 pm

    Eco-friendly heat pumps no good because our radiators are too small.

    Let me fix that –

    Expensive heat pumps no good because they are too inefficient to use radiators.

    Air source heat pumps produce roughly 3 to 4 units of heat for every unit of electricity consumed. Impressive except for two things.

    1. A unit of electricity costs 3 to 4 times a unit of gas – in normal times at least.

    2. As outside temps fall the efficiency rapidly becomes 2.5 to 3 units of heat and they struggle to heat your house – even if well insulated.

    As for giving you hot water – it is likely to be an electric immersion heater.

    A ground source heat pump will give better performance and will hold up better in cold weather, but cost double in the first place.

    A purpose built house, air tight and highly insulated (including windows and floor), with heat recovery ventilation can manage with a heat pump. But even then it struggles to give you any meaningful amounts of hot water and needs an immersion heater.

    For the average UK property, anyone who suggest scrapping a good efficient gas boiler to buy an expensive, inefficient heat pump is a cretin – but then nobody would do that would they? – Oh wait a minute!

  16. Jack Broughton permalink
    May 17, 2022 7:24 pm

    The unsuitability of heat pumps for the UK housing stock is well known, just inconvenient to the troughers.
    For the first time today I listened to a radio 4 programme called “Costing the Earth”. Basically the luvvies are only concerned with reducing carbon footprints irrespective of the other consequences, costs or sense of their actions. My radio survived mainly because the sincerely delivered nonsense was almost amusing. They want all international sporting events cancelled immediately etc.
    Unfortunately, these crackers control the UK now.

  17. M Fraser permalink
    May 17, 2022 8:28 pm

    Yes, ‘economical with the truth’, I think its more blatant than that, the chap who tried to sell/con us into putting panels on our NE facing roof was assuring they are much more efficient these days……..maybe but we’re still well north of the equator here in the Northern hemisphere! That will be no thank you then. Blantant.

  18. Duker permalink
    May 18, 2022 3:08 am

    ‘In big rooms with big radiators you need more water, so the pipes should be bigger. Now check your house, Im willing to bet that every radiator in the house has the same size pipework.’

    • Ray Sanders permalink
      May 21, 2022 1:32 pm

      Well you would almost certainly be wrong then. Pipe sizing is frequently variable over the runs. In my house (as is the norm with combi boilers) the primary pipe run is 22mm with individual feeds to radiators normally 15mm. There is a combination of 8mm and 10mm to smaller rads in the older part of the house and 15mm in the newer parts. I own another 3 rental properties and all of them have variable pipe sizes are various points ranging from 28mm primaries down to 8mm microbore.
      Do you have any idea how plumbing systems work or do you just believe every sales blog that is put in front of you?

      • catweazle666 permalink
        May 21, 2022 7:22 pm

        Exactly so Ray.

        I have 22mm from the boiler branching to 15mm to individual sections, reduced to a manifold supplying 8mm to the actual radiators

  19. May 20, 2022 8:17 pm

    Roll up, roll up…

    From Monday homeowners can apply for a government grant of £5,000 to replace their gas boilers with heat pumps.

    This is part of the government’s efforts to reduce carbon dioxide – a greenhouse gas responsible for climate change.
    – – –
    Dodgy assertion alert: ‘carbon dioxide – a greenhouse gas responsible for climate change.’

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