Time to stop promoting air source heat pumps and ask why they don’t work in the UK

(24th July 2013. Several commenters have kindly provided detailed analysis of some of the reasons why air-to-water heat pumps may be costly to operate. Others state that the technology is not at fault and blame the poor quality of the installation. Thank you very much to all those who have given time and thought to this issue. May I strongly recommend reading the full range of comments below the text? Chris)


When temperatures in the British Isles drop to unexpectedly low levels, the pattern of traffic on this web site changes. One set of search terms dominates the inquiries. Readers are looking for information on why their air source heat pump is costing so much money to run. Sold to them as a way of saving cash, readers often seem to find that the price of heating their home has suddenly increased, sometimes quite dramatically. And, moreover, the pumps don’t heat the house properly.

Today (March 25th 2013) is unusually cold across Britain and the search term ‘problems with air source heat pump’ is the single most common inquiry. Colder countries that have been using heat pumps for decades seem to be able to install them in ways that mean that homes have inexpensive and reliable heating. In the UK, with its badly insulated houses, air source heat pumps seem to be a complete disaster for many unlucky purchasers.

Below, I copy a letter I’ve just received from a lady living in the Orkneys off the northern tip of Scotland giving her experiences. Readers may also be interested in the comments added at the end of a previous post on heat pumps, including the most recent one from Jane Smith, submitted today. Despite the increasing evidence of systematic problems with air source heat pumps, government bodies such as the Energy Savings Trust continue to say that they will save money for householders living off the gas grid. Heat pumps are also part of DECC’s ‘Renewable Heat Incentive’, a scheme that is intended to subsidise the installation of suitable and effective technologies for householders. The continuing official support for heat pumps in the face of repeated failure needs to be challenged.

(Published with permission from Ms Switsur)

Hi Chris,

I don’t need a reply to this, I am just having a grouch which might interest you.

AIR SOURCE HEAT PUMPS are USELESS for anyone on a low income. I am 72. I have £130 a week total income (Pension and Pension Credit). My house had no central heating. The Energy Savings Trust conned me into having the Government Grant of £6800 and paying £2000 extra myself to have air source central heating.

It took 11 months to install because the plumber obviously didn’t know what he was about.

The first winter my leccy bill was nearly £400, and I thought it was my fault for not using the system properly, and it took me a very long time to realise that the installer had left the hot water boost permanently on.

This winter I really, really tried to economise, turning rads down and only having it on in the cheap periods. Result? a bill of £420. As I also had unexpected vets bills and an insurance excess of £250 to pay because my car slid in the snow and did some damage, I could not pay the bill – there is only £90 left to pay but (the suppliers) are saying they will cut the leccy off if I don’t sign up to their payment scheme. I can’t afford their payment scheme anyway because it is double my weekly payment.

My electricity costs are now more than 20% of my total income even thought I was promised I would save money. I HAVE SWITCHED THE SYSTEM OFF and gone back to coal. 11 months of torture while the thing was installed, £2000 of debt to pay my share, and I am back exactly where I started.

Please do advise people on low incomes not to bother with it. It didn’t heat the house adequately in cold weather anyway.

Thank goodness I have an open fire!

Regards, Julie

Julie Switsur Ardage Burray Orkney KW17 2SS 

  1. Howard R’s avatar

    Looking at some of the parts prices here:


    I should sign up for a service plan while you’re at it – £200 a year.

  2. Joe’s avatar

    I am currently building my own house, triple glazing, cavity wall insulation. With 40mm insulation plasterboard on every external wall plus ceilings. Is it wise to install air source heat pumps? Pros not using oil with the price only going 1 way- up, government grant, potentially 700 a year from the government for five or six years. Cons high to run in cold weather, ‘don’t work in U.K.’ , don’t heat the house properly, noisy, expert needed to fit it properly.
    My question will it work in the uk in a new build and in a well insulated house???

  3. Douglas Haigh fidhe’s avatar

    If the following is done then it might work–but remember you are using the most expensive fuel.
    1. accurate heat loss (to BS EN 12831) calculations taken out and ASHP sized to provide 100% of required heat without use of in-built electrical resistance heater
    2. Underfloor heating designed to operate with ASHP
    3. A buffer vessel is a great help.
    4. Sensible controls incorporating weather compensation
    5. Fit the ASHP where the noise will not irritate you or your neighbours
    You would be better advised to consider a solar assisted floor heating system.
    Doug Haigh

  4. grainne Kelly’s avatar

    We have had an air to water heat pump installed over 4 years ago. It cost us over 3k in 3 years for maintenance as it did not heat the house or the water since the installation. Once again the temperature has dropped in the UK and it cannot heat the water to the required temperature to heat the underfloors. It is a complete waste of time and the installation companies expect you to be an engineer to operate it. It shouldn’t be so difficult. It is a black or white situation. It either can or cannot heat the home when the temperature outside drops. It is not much good to me having heat all summer and the first sign of frost it malfunctions.
    We have paid over 15k for the unit and maintenance now and out energy bill is sky high. If someone out there knows some genius who believes that these things work, please feel free to contact me.

  5. Douglas Haigh fidhe’s avatar

    first step is to determine what the heat load is on your house, you will (or should) get that from the UFH installer; second step is to determine the rated output of the heat pump.
    I’d be interested to know what those figures are

  6. grainne Kelly’s avatar

    Thanks for that Doug, How can I get that information?
    I can’t help feeling that we have been sold something that was grossly misrepresented.

  7. Douglas Haigh fidhe’s avatar

    the company that installed your heating should have details of heat losses, equipment specified, pipe spacing etc etc. The heat pump will have a manufacturers data plate fixed on it, this will have rated output etc.
    What are the floor constructions?
    How big is the house ( sq.m.)
    How many UFH manifolds?
    How old is the house?
    What standard of insulation?
    Do you have a set of scale drawings of the house?

  8. grainne Kelly’s avatar

    Our system was fitted retrospectively as the house was already built with underfoor heating and running on oil. the floors are all byson slabs and solid marble tiles throughout, both upstairs and downstairs.
    We have two pumps for the UFH, one upstairs and one downstairs with 10 heads on each.
    The Waterkotte system we have is 11k I think….
    House is 10 yrs old, but system was fitted 4 years ago
    House is approx 3k sq ft, H shaped, two storey.

    Not sure if this helps.

    The heating has now stopped and the temperatures are dropping to 14 in every room today and the return temperature is 24.

    The problem I have is that the company who installed it don’t know what the problem is and it has cost me 3k on top of the installation cost in call out fees as this keeps happening everytime the temperature drops. I cannot continue paying them when they clearly do not know why the system does not work.

    On top of that, our energy bill for 2 months was 800stg, so we are not exactly saving. We are averaging 280-300 per month over the year.


  9. grainne Kelly’s avatar

    I forgot to mention the insulation, I do not have the drawings so I don’t know but we did have someone come out with the heat detector and they were able to tell us that the house is not losing heat through the walls or roof.
    Sorry I can’t be of more help than that.

  10. Douglas Haigh fidhe’s avatar

    first thing to try is a little detective work. Make sure the heat pump is working and switched on, then turn the valves on the ground floor manifold to the ‘OFF’ position, this will just about halve the heat load and after a while the 1st floor heating should be showing an improvement.
    I think it might be better if you phone me first on 07778 233924

  11. grainne Kelly’s avatar

    thanks Doug,
    I will give you a buzz, I would need to talk it through with you.
    Sitting here mid hurricane with driving wind, two kids and no blooming heat!

  12. Jackie’s avatar

    Hi, we too have been mis-sold a Husky Heat Pump and have had 2 years of on and off heating and the bills are sky high. Someone should be done to stop companies selling these in the UK

  13. Liz’s avatar

    Crumbs I was just about to buy an air source heat pump you guys have really put me off …I’ve had a bad experience with a thermaflow boiler but with electric being my only option I’m not sure what to do now any ideas from anyone…I’m open to any suggestions …I need a powerful boiler ..finding info on any electric heating systems is difficult cheers :)

  14. Douglas Haigh fidhe’s avatar

    unless your house is new and well insulated and your heat distribution is by floor heating then you really should consider something else.

  15. Deb’s avatar

    Anyone know anything about SDEEC ASHP’s I have one but as the company who istalled went bust I don’t have anyone reliable to maintain it for me.

  16. Hamish’s avatar

    Unfortunately it would seem that many heat pump installations are sold by salesmen with skills restricted to marketing rather than a technically competent sales force who will give an honest response to genuine enquirers as to the suitability of a heat pump solution to their particular situation. Early air source pumps were plagued with freezing problems here in the north of Scotland, where with a high humidity the wisdom of this particular solution was anything but advisable. Early solutions to this problem – large immersion heaters to thaw-out the unit completely negated the whole concept of an energy efficient heating system. Modern variants now redirect the heated water back through the heat pump plumbing to keep it from freezing – a much more elegant solution , and almost acceptable. It has to be faced however that an air source heat pump is inevitably going to be inefficient as the temperature nears, and drops below, freezing. To their credit many suppliers are quite open about this and do not recommend Air Source Heat Pumps in some UK high humidity situations.
    The secret is an informed sales force with an honest and open company ethos.
    My own opinion is that a heat pump solution is only really attractive with underfloor heating in a very well insulated home – making this form of heating ideal for a new-build.
    Seeking local advice re an air-source solution proved beneficial in my case. I opted for a ground-source heat pump solution in which a supply temperature of only 27 degrees C was sufficient to keep the house warm when -10 degrees C outside. I tested this using a simple water tank and an immersion heater supplied by my heating engineer to prove that the heat pump solution would work – before the heat pump was installed. Now this is what I call good pre-sales support. Our IDM heat pump is now up and running and is proving excellent.
    So – have a look at your heating challenge from another perspective. Ignore the heat source and design your system to rely on warm water – not radiator temperature water. If you get this design right let an air-source or ground source heat pump produce your warm water and that will work wonderfully. Don’t start your calculations from the wrong end with a technology that is designed to produce only warm water very efficiently.
    It will all be worth it – it was for me. Good luck – and don’t be sold by the technology, be sold by good design and an elegant technical solution put together by folk who know what they are doing.

  17. Paul Cartwright’s avatar

    All, please do not take this as a punt for work, however I did want to reassure people that there are installers and service engineers that work in the ASHP industry who have some experience and technical ability.

    The problem we are seeing is the herd moving over to the potential boom of green technologies with little experience of the ASHP technology. The people who bother to take a course are sometimes not the people installing or sizing the units. The room by room calculations are a must for sizing your ASHP.

    There are a couple of posts regarding retro-fit air source heat pump on an existing under floor heating pipe work. This will never work as the calculation of existing pipe size was calculated at 80 degrees flow temp (delta T) and not a max of 55 that the ASHP can supply, the ability of the emitter to get the heat into the room is diminished, result is a cold room.

    Please do your research on your installer and remember their ability to give you thorough design plans, a good assessment of your installation and MCS compliance paperwork will be directly related to their ability to install the system.

    Always always always do your own research.

    If you are stuck in the midlands please do not hesitate to get in touch.

    RF Blount & Sons ltd

    or email paul.cartwright@rfblount.co.uk

  18. Leon Slade’s avatar

    I am having an air to water system fitted,I alaready have a 10 tube solar water heating system and a 1.4 electric panel system,6 panels.I am geting rid of my 2 boilers,1 is u/s,the other is over 20 years old,I am assured that the 14 Kw air to water system will heat the whole house,8 rooms,with a saving on gas of £1000,but £300 in electric a year,the solar hot water is 30 c in winter and over 80 c in summer.I use radiators with the air to water system,I hope it works OK,the installers are MCS and other accredited.

  19. Leon Slade’s avatar

    The prev. reply I said the electric was £300 a year,I ment £300 extra a year
    with £60 to £100 gas for cooking only,the hot water solar tubes will keep up the temperature in the day,the electric panels will help cooking stove to run the heat pump,
    I will ditch the gas later by getting an electric cooker,no gas explosions to worry about and the heavy bills to go with the gas.

  20. Chris Brock’s avatar

    Hi everyone I have been approached by customers with regard to air source heat pumps as a means of offsetting electricity prices fir water heating and underfloor heating. I have always thought that, like electric showers, when you want heat is when the water or in this case air, is the coldest and as such the least efficient. Has any one as yet got some positive outlook on air source as we are not in the Buisiness of giving bum steers to customers for the sake of a few extra quid.

  21. Steve Connolly’s avatar

    My company makes heat pumps (see arriba cooltech) for large commercial applications (50 kW to 100 kW) and we also have a technical team that is heavily involved in trouble shooting all manner of engineering issues with third party heat pumps.

    The reason behind the poor energy efficiency in many heat pumps is 80% likely to be down to poor design of the thermal tank and the heat pump controls system. This is more of a factor than the British weather or the heat source (ground or air).

    Thermal Tank Design: It is essential to use a tank that is capable of storing its water in thermal layers……hottest at top, slightly cooler in the middle and cooler still at the bottom….

    Controls: The heat pump should be capable of working in two modes; (i)production of 40 DegC water for UFH and underfloor circuits (ii) Production of 55 DegC water for bath water. On average the ratio of hours spent in mode (i) compared to mode (ii) should be around 6 to 1. The controls should be capable of automatically managing the mode switching. In mode (i) water is sucked from the bottom of the thermal tank, through the heat pump and then pushed back to the middle of the tank. In mode (ii) water should be drawn from the middle part of the tank and then through the heat pump and back to the top of the tank. Mode (ii) operation requires at least 2 passes through the heat pump (40 to 46 and then 46 to 52 DegC etc)

    Spoiler Alert…..Most manufacturers do not understand this…..and hardly any installers get it either. Immersion heaters should not used at all (unless the heat pump breaks down).

    One last thing….its obvious….but you shouldn’t need to pump water through your heating ring-main at any warmer than 40 DegC.

  22. Douglas Haigh fidhe’s avatar

    your sentence regarding ‘offsetting electricity costs’ is interesting. The likely result to your clients is offsetting upwards ( almost vertically) An appliance that is supposed to provide heated water to pump around the distribution system should not be tested at 7 deg C ext. air temperature and 35 deg C water flow temperature. End users need heating that will cope with the lowest external air temperature where they happen to live.
    Doug Haigh fidhe

  23. Steve Connolly’s avatar

    Heat pumps can work well so long as they have an ability to switch between two output temperatures (one for UFH the other for DHW). Also it’s necessary to have a thermal tank that allows temperature layering so that a temperature difference of around 25 DegC can be maintained between the top and bottom of the tank

  24. grainne kelly’s avatar

    Thought I would update you all. We had the heat source pump taken out and our electricty has gone from averaging 90units per day, which is 4.5times the average for a house of our size, to 18 units per day which is below the daily average.
    This means that the heat source pump cost us more to run than the oil as we run at an average of 100litres per week.
    Costly to install and costly to run with no payback over time.

  25. Barry Watson’s avatar

    No problems with my Worcester air to water heat pump.
    I bought a house last may with system installed which was in preference to oil and lpg as house in the country.so far I have no complaints at all with its performance but a neighbour with same system gas had lots of niggling problems. I reckon t b ey are sbout same running cost as nornal gas and electricity together.pity I can’t fit photovoltaic system to the house topay for cost of running.

  26. Nik Sargent’s avatar

    Reading this with interest as we are about to go for an ASHP on a new build with both floors UFH – in the borders region of Scotland.

    The original article did lose a little credibility for me by quoting an installation which by the own admission of the owner was seemingly botched.

    The comparison with coal is somewhat inconclusive also – unless there is quite an expensive system installed, it may well just be heating a single room, not heating the water, and, being an open fire, sending half the heat up the chimney. For interest I found this comparison table from 2012 on pricing.. Not to mention the owner not being familiar with the system settings. This, to me, all seems potential avoidable.

    I found this comparison table of fuel pricing interesting:


    While electricity is far more expensive, in Scotland it is far greener (50% renewable by 2015 i believe, aiming for 100% renewable by 2020 – a big selling point for me) – coupled with an RHI rebate which practically halves the electricity cost.

    So, really you would have to running an ASHP at 1 (or thereabouts) COP to be feeling the cost pain of the examples quoted here. Anything approaching COP of 2 should actually be working out cheaper than coal, indeed cheaper than any alternative?

    Anyway – setting all that aside, it seems to me what stands out amongst the comments are poorly designed or botched installations that do not deliver – as would be expected; a result presumably of incentivised sales tactics, inappropriate retro-fitting and minimal due diligence.

    Well, I just hope I don’t eat my words when my system is up and running – but I suppose there’s always solar as a means to provide some of the power in future… :-0

  27. Steve Connolly’s avatar

    You are doing the right thing by choosing UFH. The efficiency of heat pumps tails off sharply once the output temperatures are set above 40 DegC. So with UFH you should avoid falling into the trap of running with excessive temperatures.

    However, you need to pay special attention to the following 3 points when choosing the heat pump and hot tank

    1.You need a tank that is able to maintain a temperature difference of at least 16 DegC between the top of the tank and the bottom of the tank

    2. You need a dual set point in the heat pump control system that can switch between a 40 DegC (or lower) output temperature for the UFH and towel rails and 50 DegC (or higher) for the bath water

    3. You need to choose a control system that DOES NOT have weather compensation….most heat pumps do have these this function built-in….stupid idea developed by heating engineers who understand nothing about refrigeration. REMEMBER a heat pump is simply a refrigeration machine. If you try to operate it as if it were a boiler you will waste energy….which defeats the whole point of using a heat pump.

    I can advise you in more detail on this if you contact me offline….I run a company that manufactures industrial refrigerators and heat pumps

  28. nik sargent’s avatar

    Thanks for your reply Steve and your helpful insight.
    I still have a lot to learn, even just to get to grips with the principles you have quoted above.

    It’s also fairly new to my builder but he and the architect have engaged some specialists who can provide the whole solution, so I will make sure they are taking account of the features you have described above. I’ll be wanting to sign off any decisions :)

    The dual temperature control makes so much sense, and I can see now why the actual control system and storage is, if anything, even more important than the pump itself – and why there is a decent price tag for it attached to their quote :) If anything, that gives me more confidence in the designer/installer.

    I would not ask you to take time out to explain, in particular, point 3 of your comment – but I would love to know the reason. Is there somewhere on the web I can find out?

  29. steve’s avatar

    You may or may not find this on the Web. But I am telling you as a refrigeration design engineer that weather compensation on a heat pump is a terrible energy sapping idea. The idea behind heatpump is to scavenge the condenser heat out of a stream of high pressure refrigerant and the to use the scavenged heat to warm up your house. If you attempt to scavenge heat from the refrigerant condenser with overly hot water you will simply overload the refrigerant compressor. Better to just let the house warm up at its own pace. With good insulation this will happen pretty quickly without need to boost the hot water production temperature

  30. nik sargent’s avatar

    As part of contributing to this thread I would also like to add an end-user perspective; that of a reasonably intelligent & scientifically minded individual, though not an expert in heating technology (of any kind).

    We are building a new house in a rural area near the border of Scotland. As there is no mains gas, the default option for heating is oil. As we know, oil is at the expensive end of carbon-based fuels. I do not want oil, for the following reasons:

    1) I simply do no want an oil tank, nor the risk of theft of oil, in my garden; I do not want to be wholly dependent on a single raw source fuel, nor at the mercy of delivery trucks.
    2) I am thinking long term – oil is not going to get cheaper only more expensive
    3) I am thinking long term – I do not want such a dirty carbon unfriendly fuel – in a perfect world I would power everything from my own solar and microgeneration. But we are not ready to make that leap yet. I need a stepping stone.
    4) As i understand it, Scotland’s grid already comprises 40% renewables and the target is 100% by the end of the decade. [ http://news.scotland.gov.uk/News/New-Stats-show-another-record-year-for-renewables-79a.aspx ]
    This is brilliant – by using grid electric as an interim solution, it gets cleaner and cleaner every year without me having to do anything.
    5) an electric solution leaves me with options at a later date for increased self-sufficiency – e.g. my own generation of power, addition of solar etc.

    We are choosing ASHP mated to Underfloor heating both upstairs and downstairs.

    All the arguments about demand on the grid and efficiency of power stations and the carbon footprint are all valid. But nothing is static. The energy landscape is changing and I believe will continue to do so even more quickly as more and more people realise that climate issues are real and the planet is being royally screwed up for their kids. You might be worried about energy costs now, but i believe “you ain’t seen nothing yet”. I need the grid now for the short to medium term, but hopefully I won’t need it at all in the long run.

    For me, connecting to the grid is a way to essentially diversify the raw sources of my energy and protect myself from the rough and tumble of any specific fuel source. Moreover, it will only continue to get greener and greener. In short – to future proof.

    I read recently* that if we harvested 1% of the available sunlight in the UK we could power the country. That is so incredibly staggering that it defies belief that the country is not putting all its efforts into investing in that kind of solution, which would provide energy security and over time cheaper and cheaper energy.

    [*I think it was newscientist, so presumably credible; there's actually about 1Kw per sq metre of energy in the sun's radiation http://en.wikipedia.org/wiki/Sunlight ]

    It goes to demonstrate the stranglehold that the carbon industry over us. It’s hard to see how that stranglehold will break while anything but the last drop of fossil fuel exists (look at the excitement over fracking). So, all that remains is for individuals such as myself to be disruptive and choose an alternative path. A thousand mile journey starts with the first step.

    I know that Ground Source would be a more efficient option for me, but for several reasons I do not want that solution. First, I don’t want components of my heating system buried deep underground. But more importantly, I simply don’t have the capital to invest. That’s it, end of story. So, i am left with compromising on an alternative.

    The RHI scheme is a welcome boost to my investment, but I would almost certainly do this anyway for all the reasons above (1 – 5) – which as you will see are not driven by cost alone. The bottom line is – I care. I care about the future especially having just had a child, and about trying to make some contribution to improving it. (I’m sure there are critics who will call it misguided, but you have to bear in mind this is only part of a bigger personal strategy – such as how much i travel – and it is ever evolving)

    This means actually making a change, actually making some choices that are not purely selfish or short-termist. It’s a bigger view than “does an ASHP deliver 1.6 COP at -1 degrees into a wet system..” Poring over technical specs, while important for designers, is like having an argument about which car is best based on 0-60 and torque curves and mpg; (and no-one can define “best” anyway) – instead of getting out and enjoying driving it the way it was intended. Frankly, if I (only) have to use my Dyson Heater to top up a couple of days a year, I will jump for joy; I had to use it almost two weeks solid this year when my gas boiler broke down and could not be quickly repaired. My life does not unfold on paper (no pun intended), no single day is statistically average.

    I actually think on balance the RHI scheme, and the inclusion of ASHP, is a good idea; it is not intended to deliver 100% efficient heating solutions. It’s aim is to drive adoption of new technology (I could entertain you for a whole day on that specialist topic of mine) and drive new consumer behaviours. The architects of the scheme have had the sense to define it, constrain it and time-limit it; in that respect they have done the right thing. A lot the anti-arguments about schemes such as this hinge on the notion that it opens the floodgates and suddenly the world is turned upside down.

    That is simply not the case; that is not how adoption happens; nor is it shown to have happened in the past. These schemes are basically a “nudge” to suitably-minded folk. Schemes and incentives will come and go, just as personal and national energy strategy will evolve, as indeed the available technologies will. One day we will have a solar solution that is closer to 97% efficient than it is to 3% efficient; it will be embedded in all our windows / walls and our homes will be self-sufficient with free energy – and we’ll wonder quaintly why we ever argued so much over our current solutions.

    It has not taken me long to spend some time with mr google and find out all about the pros and cons, limitations, benefits and so on about ASHP – to come to some understanding of the risks etc. I do think that anyone that has not invested that small amount of time and effort for themselves is master of their own destiny. If you let a salesman walk into your home and convince you to part with 10 Grand of your life savings, you have a responsibility to do some due diligence, if you care about your life savings.

    Balancing all the above factors, I believe ASHP will be a good solution for us, and offers us the scope to continue improving the way we personally consume and pay for energy. It will help me achieve my own personal green targets by virtue of Scotland’s forward thinking. In 15 or even 10 years time I doubt i would be making the same choice, as yet more alternative technologies will be available, but sadly, I don’t have a tardis.

    Only time will tell if this is a sensible decision, but subject to all the proper due diligence and care, I think it is.

  31. Douglas Haigh FIDHE’s avatar

    What a pleasure to read such a well balanced account. The use of solar thermal as a means of heating support is actually already here. It isn’t new or magic technology, but it is something that RHI, MCS, DECC etc etc are very wary of because they simply do not understand it, and as a result have provided miles of red tape in order to block the reduction of carbon dioxide while the rest of Europe just gets on with it. If you want to know more try my email, doug@begetube.co.uk
    If you go for ASHP you must make sure that the appliance will cover 100% of the heat load ( properly calculated of course)

  32. Paul D’s avatar

    Domestic Renewable Heat Incentive Scheme Regulations 2014
    1: These regulations were approved unanimously by a committee of the House of Commons on 2/4/2014 :-
    2:30pm – Room 9, Palace of Westminster
    Fourth Delegated Legislation Committee
    Draft Domestic Renewable Heat Incentive Scheme Regulations 2014
    Location: Committee Room 9, Palace of Westminster

    2: I note two remarks from the Minister’s presentation to the Committee :-
    1: “the retrofit [heat pump] is the biggest challenge”, and
    2: “a minimum efficiency of [an SPF of] 2.5”

    2.1: In respect of heat pumps, the draft Regulations set up the central deceit by defining an ‘air sourced’ heat pump as having a ‘liquid discharge’. The purpose of this piece of nonsense, I suggest, is to hide the most efficient heat pumps currently available, whilst the Regulations try to push the inefficient pumps at a gullible public.

    2.2: An SPF (a seasonally adjusted CoP) of 2.5 is poor when compared to a CoP of 5.5+; my pump is rated at a CoP of 5.7 and I know of one that does over 6.1. Why does this matter? I think that DECC’s Chief Scientist should be allowed to explain :-

    ‘Dear Paul D … ,
    … Yes. You have to be careful exactly what “system boundary” is being used to define the performance of a real heat pump (there are about 4 system boundaries, for every one of which you can define a Coefficient of Performance!) – but in general terms what you said is exactly right. The CoP is the heat to electricity ratio. If you halve it then you need twice as much electricity to deliver the same output.
    Yours sincerely, … ‘

    3: If ‘you need twice as much electricity to deliver the same output’ then the electricity bill will be double what is really needed. So a pump with an SPF of 5.0 will run for half the cost of one that runs at 2.5. Pumps with an SPF of 5.0+ are available and I have one in my house. It has cost £123 for electricity to run this pump through this winter, so far, and in the process saved £422′s worth of mains gas, on a year-on-year basis. Use of the gas-fired boiler for space heating has been minimal; its main duty now is heating the hot water. The payback on capital (about £650 for the pump + installation, electrics and instrumentation – total less than £2000) looks like six winters which is reasonable and that achieved with no subsidy.

    4: Nobody with a good fossil-fired (LPG, oil, mains gas or coal) boiler and hot, wet radiators should allow a heat pump installer to touch the boiler. The heat pumps that can achieve an SPF of 5.0+ are called ‘air conditioners’ and, in heating mode, they far out-perform the high temperature air-to-water retrofit heat pump that the Regulations are pushing.

    5: In respect of heat pumps, the Scheme set up by these Regulations is entirely voluntary and one to avoid if you wish to maximise your :-
    1: financial savings from running a heat pump, and
    2: carbon savings.

  33. Steve Connolly’s avatar

    The reason that air to air heat pumps are discouraged is that they rely on (soon to be banned) HFC refrigerants.

    Air to water by contrast use only a small quantity of HFC and this design is in principle the right one to go forward with. The next phase in all of this is for the government to insist that all new heat pumps use natural refrigerants.

    I predict there will be announcements on the HFC situation early in the next parliament. Unfortunately there are no suitable engineering solutions that allow air to air configurations with natural refrigerants.

    It’s a bit technical but I can expand on this last point if anyone is interested

  34. Howard Richter’s avatar

    Really? Tell us more, please!

  35. RB’s avatar

    I would like you to expand. A quick search suggests the Daikin Altherma uses R410 and the IVT Greenline has R407C.

  36. Steve Connolly’s avatar

    The refrigerants that you mention are far from green. they are in fact powerful greenhouse gasses in their own right and are subject to a globally orchestrated phase down (this is the politcally correct way of saying they will be totally banned)…..and bearing in mind that politicians have to be seen to act decisively on greenhouse gasses an acceleration of the HFC phaseout programme is highly likely.


  37. Steve Connolly’s avatar

    There is plenty of information about natural refrigerants here:

    The four main ones are butane, propane, ammonia and CO2. For household use it is highly unlikely that Butane, Propane or ammonia would ever achieve safety approval. That leaves just CO2….which is in fact the best heat pumping refrigerant in the world as far as higher temperatures are concerned.

    The difficulty with CO2 in heat pumping applications however is that it is necessary to operate with pressures of over 100 bar (1500 psi) compared to typical maximums of 40 Bar with R410a in heating applications. These pressures are potentially lethal and require heavy duty pipe work and pressure vessels. For this reason it is usual in CO2 applications for the section of the plant that contains the refrigerant to be located in a plant enclosure away from the lived-in area of the house.

    For household applications the best heat pump is the Sanyo CO2 unit….although for some crazy reason this has for the moment been removed from the European market.

    If anyone is really motivated and is not shy to invest appropriately I can make you a CO2 heat pump. Any size between 10kW and 80kW. Built as bespoke one-off’s so not price competitive with run of the mill household heat pumps. But top of the line British engineering….better than anything from Japan

  38. Howard R’s avatar

    Wires have become crossed – when I said ‘tell us more’ I was referring to your statement

    ‘The reason that air to air heat pumps are discouraged is that they rely on (soon to be banned) HFC refrigerants.

    Air to water by contrast use only a small quantity of HFC’

    So, tell us more, please!

  39. Steve Connolly’s avatar

    I meant that you can’t use natural refrigerants in air to air systems because that would mean pumping dangerous stuff through occupied spaces.

    The options being Butane, Propane, Ammonia or 100 bar CO2….hence the best engineering solution is to keep the refrigerant in a cordoned-off plant enclosure and to pump water to and from the plant

  40. Martin H’s avatar

    Hi Paul D, good to see your commentary again. My 2x Mitsubishi SRK “Air Conditioners” worked admirably through the North of Scotland winter weather, I certainly had a much warmer house with a calculated 41% reduction in electricity usage, but to be honest it was not a very cold winter up here, so I dare say it my electricity bill could have been more. Having said that my upper rooms were kept warm throughout the winter which I could not afford to do the year previously. I only used the 1x bathroom storage heater overnight throughout winter, and the other St/Heaters were used periodically.

    I had to switch off the one SRK that is installed in the loft on a handful of occasions due to it being near 0deg C. having said that I am still delighted with the overall performance.

    How did your SRK Loft Installed unit perform? After the handful of times I switched off the Loft Unit due to the loft freezing, I segregated the loft with bubble foil with the last section from the unit having an extractor fan pulling discharged cold air out away from the sun warmed loft space. It works perfectly. I inserted a “cheap” wire thermal probe into the loft and the thermometer side is just at the loft hatch which I can read easily. Anyway it is good to see you are still active.

    Regards Martin (Lybster near Wick)

  41. Matthew Hanson’s avatar

    Hi I have a dakin altherma ashp 16kw split system. my overall opinion is that it is a very good system when installed properly and you know how the system works, I moved in to the house in august 2011 & the hp was already installed and working correctly. things were good until that December, when the months electric bill was £300.00, the heating was on constant for the whole month, The system had not been installed with a programable room stat & I had not grasped the controls of the heating. my engineer installed a Programable room stat (just a standard salus wireless stat ) & explained the controls now my bills are a lot better my monthly dd for a 2 bed house is £70.00 its an old house with solid walls & avarage insulation & oversized radiators . the key is not to let the house get to cold. the system is nevver off as such the room stat regulates the temp at different times of the day eg 15 when out 17 when in & 20 when sat watching telly. a good engineer is priceless 7 paying that bit more for a quality install is well worth it.

  42. Richard C’s avatar

    Very interested by your comments Steve on the mistaken thinking behind weather compensation controls on AWHPs. Was looking at the Samsung which has it…can it therefore be disabled? They supply the cylinder too with all controls needed attached it seems. So should be much easier for an installer to get right I am guessing?
    Have to also check on the temp differences between top and mid and bottom of the cylinder you speak of. It would be running UFH in what will be reasonably well insulated building although stone shell dates from 1883.

  43. Steve Connolly’s avatar

    Please don’t be lulled into thinking that the Japs have got it right with heat pump controls…just because it’ s a brand doesn’t mean it works properly. In my view you would be as well off to go for a basic heat pump such as the CTC base model and to buy a decent thermal store such as the one from Chelmer and then get you contractor to fit his own controls.

    I might be able to offer a controls package if you get stuck with your local guy.

  44. Richard C’s avatar

    Thanks for coming back Steve
    I am just investigating to get costings clear prior to the renovation starting and being only technical to a limited level. And as yet I have no local guy that I know can do this well.
    But this is a good site to start and you seem to know your stuff… and it seems essential to get the heating options sorted before planning is finalised. I have done two renovations over the years both in Cornwall. First used a conventional oil combi and rads, second was entirely electric using a very large cylinder with a tank within a tank system ( a form of thermal store?) with immersion heaters all on Econ 10, with DHW and UFH on ground floor and rads upstairs. This worked well except maybe for the rads upstairs. Its partly reverse level with front room up and I use the woodburner there a lot when cold. but then I get wood for free.

    Two things strike me. One this as technology is still working through and the other is price. The Samsung 9 KW i had looked at ( which was cheaper at Urban than where I had first looked by a cool £500 so I can see prices vary!) at just £1830. which with the Samsung 300L cylinder with all controls at around £2400 makes it fairly cheap option at first sight and integrated to boot.

    Just looked at the CTC Ecoair 107 ( not sure yet what KW this is)…but its £3645 on Urban which is twice the price … then theres the thermal store itself. Roof not really ideal for solar facing NW and shaded and not much interest in hooking up the upstairs woodburner to back boiler etc just need the the air pump for DHW and UFH.
    I take the CTC is time tested and high quality but is it quiet? because that is very important to me and close by neighbours…

  45. Paul D’s avatar

    Some cross-links to the Green Building Forum :-

    1: Heating and cooling: Do Air to Air heat pumps have higher COPs than Air to Water or Ground Source systems?

    2: Heating and cooling: Shouldn’t A2A heat pumps be receiving more attention?

    3: Heating and cooling: Where Are Those Happy Air Source Heat Pump Owners?

  46. Robert Duncan’s avatar

    Hi Martin H,

    I am amazed that people in Orkney and Caithness are getting involved in ASHPs etc – only because I know little about it all (unlike most of the clued up contributors here) and it is so hard to find trained and reliable installers for anything up there.

    I have a croft house (old!) in Keiss and am wrestling with what to do to replace the storage/panel heaters which cost a fortune to run. Mainly, I need a system which will “tick over” during winter, not having to reach temperatures required for comfortable occupation but which can be turned up for the odd week when we are there. Do you have any advice on who to approach in Caithness (ie installers)? Cheers. Rob D

  47. Martin H’s avatar

    Hi Rob, there are a “few” installers but when I was contemplating the installation of ASHP’s I was given an installers name to contact from a local electrician. I was not impressed with the installers response to say the least. He had done Air to Water HP’s but never Air2Air ? He did not even offer an alternative installers name. Who to contact, Plumb Centre Wick can arrange ASHP’s so I would expect they know an installer. I am NOT recommending the products they offer as the COP is not so good.

    Depending on whether you have a few tools they are relatively easy to install although they need to be inspected/tested/certified by an electrician with Part P (for the outside Safety/connection) they can plug into a normal 3 pin plug internally. I purchased two Mitsubushi SRK 25 ZJX-s from Saturn Sales (on the web) which offer a COP of up to 5.2 The SRK 20 ZJX-s COP 5.6, smaller units are better economically. There are cheap units out there but beware they have a low COP (2+). We reduced our electricity consumption by 41% year on year (albeit being a mild winter so a real comparison is difficult to give ) but, he house was definitely warmer with ASHP. We used the bathroom Storage heater only.

    Not sure how well insulated the croft is but I have insulated a lot of the downstairs walls so this also helped in power reduction.

    Dependent on internal and external temperatures (+your personal temperature setting) my ASHP’s produce a significant heat whilst drawing between 350 – 800Watts

    For good units speak to John at Saturn Sales, also for best prices including postage + accessories tubing, insulation and clips.

    I am not far from Keiss, you are welcome contact me and to come and see what I have here, I am in Lybster, The Old Police House (old Lybster Police phone Number “really”) just off the A9, going towards Wick, it should be going in your direction if you are coming from the South.

    We are all electric, and also suffered from the exorbitant costs of storage heating. Am I happy with the Mitsubishi’s? Definitely.

    A tip: watch what you buy as there are lots of letters and numbers for the ASHP Models but they have very different performances (COP’s). There is an ASHP with a COP of over 6.

    There used to be a Guy on this forum who gave “Free calculations” for ASHP and costs etc, Paul D. You might be able to source some from past posts.

    Hope you get what you need. Please feel free to call Robert.
    Regards Martin

· 1 · · 4 · 5 · 6


Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>