Are heat pumps any good?
This is a transcript of a webinar delivered by Tony Baker, domestic energy and retrofit assessor for Marches Energy Agency and Dave Green, energy efficiency expert. You can watch the webinar here.
Who are we?
Marches Energy Agency is a charity. We’ve been working in fuel poverty for a very long time and more and more we’re working in decarbonisation work. We’ve become quite a big organisation – there’s more and more demand. I do want to underline that we are a charity – we are therefore impartial and independent.
Future Ready Homes offers retrofit advice to everyone and anyone. Retrofit means essentially adding something to your property, or changing the property, to improve its energy efficiency, and to make it more sustainable. So possibly improving insulation, fitting solar panels, or, of course, fitting a heat pump should you wish to.
I’m a qualified domestic energy assessor and a retrofit assessor.
I have to be honest: right now I don’t have a heat pump. We’re living in a rented house, but we’re hoping to buy it and put in a heat pump. I was previously living in Clun in a barn conversion, and we had a heat pump there. And as a landlord, I’ve put a heat pump into a property I own in Shrewsbury.
I also want to make clear. I’m not a technical expert. I’m not a heating engineer. So this webinar is described as an introduction for a very good reason.
What is a heat pump?
It can be a ground source heat pump, a water source heat pump, or an air source heat pump. As the name suggests, what it’s actually doing is not burning anything like a gas or an oil boiler, it’s pumping energy from a natural source. So the name source is important: the ground source or the air source or the water source. Ultimately you’ll realise all of that energy derives from the sun. So that’s effectively solar energy.
Ground source heat pumps: they no longer justify the enormous cost of installing them. So we’re focusing today on the most common inexpensive type, which is an air source heat pump.
It works by extracting energy from the air and through miracles of compression and refrigerant, it uses that energy to heat water which runs through your heating system – your radiators or your underfloor heating – and to fill the hot water cylinder.
It’s compression that allows the heat pump to achieve the remarkable efficiencies that it does because compressing a gas creates heat. That’s the basic physics behind it. By remarkable efficiencies I mean 400% efficient or even more is possible. Which means that one unit of electricity used by the heat pump can deliver 4 units of heat.
Why should I get a heat pump?

The answer is climate change. I’m not going to bang on about climate change. I want to talk about the good news, which is we can all take a big chunk out of our own carbon footprints by installing an air source heat pump as you can see from the figures there.
The bottom line is that electricity from the grid is becoming more and more green, more and more clean, as more and more renewables come online and hopefully coming online very fast. The government has set a 2030 target for a decarbonised electricity grid. So you can decarbonise your heating by moving to electricity as the fuel, as it were.
And the point about this is: it’s fairly straightforward, it’s fairly painless, and it doesn’t involve any sacrifice.
I fully understand a lot of people don’t want to be told what to do. They don’t want to have behaviour change forced upon them. People don’t want to give up eating beef, or whatever it may be, flying off to the sun. Those sort of sacrifices, because of climate change, are going to be challenging. But changing your heating from one heating source to another is perhaps the most straightforward thing you can do. And it is impactful.
Just to be absolutely clear: I’m a big fan of combi boilers. They’re terrific at what they do. They produce water at high temperatures, they produce water on demand. They’re efficient and they’re reliable. They’re pretty cheap. If you go to a trade outlet, a gas combi is about £650. That may come as a surprise to you because installing one costs quite a bit more than that – about £1,500-£1,800.
But there’s one enormous problem with gas and oil boilers… They burn gas and they burn oil. Gas and oil obviously won’t last forever. But they also cause climate change. So we need to wean ourselves off them.
Electricity can supply your needs for heating and cooking, possibly a car as well. It is possible to disconnect from the gas grid entirely, right now. This is the direction of travel, something that is becoming normal and will be more normal. There’s a financial incentive in that – the gas standing charge. It has been more expensive than this, but at current rates it costs you over £100 a year.
There’s a lot to be said for putting in a battery to store electricity – it gives you more security at home. And if you want a backup for your heating, a wood burner is an option, though these come with their own issue, particularly around pollution. (see woodburners webinar)
Is a heat pump suitable for my home?
Presumably the people who are asking this question, the home in question is particularly old and draughty. Bath Abbey has not been hugely retrofitted, so far as I know, but it does have a standard air source heat pump (air to water) heating system to heat it. So if a heat pump can heat that, it can pretty much heat anything. If a boiler can heat the property, then a heat pump can heat it. It may have to work quite hard to generate that heat, but it can do it.
A heat pump is at its happiest when it’s working efficiently, just like a gas boiler or an oil boiler. If you do have a very draughty old house, and there’s no insulation in the loft, or the heating system has been poorly set up, or you have radiators which are too small to deliver the heat, whatever heating type you have it’s going to have to work hard, and therefore it’ll be expensive to run to to keep you warm enough.
The big difference with gas is that a condensing gas boiler is efficient at around 55 degrees. Whereas a heat pump is a lot happier at 40 degrees, or lower still which is why it’s often advisable to have larger, more efficient radiators when you’ve got a heat pump, or, better still, have underfloor heating because then you can run it at a lower temperature.
One of the tricks to getting maximum efficiency out of your heat pump is to run it low and slow, as we call it, but we’ll come back to that later.
So for now the answer is, yes: a heat pump can heat your home.
Do heat pumps work in cold weather?
Again the answer is, yes, heat pumps work, even in very cold weather. The refrigerant that is used in most heat pumps nowadays boils at -15 degrees. That’s pretty cold. Heat pumps can work lower than that, they will work down to -20 or even -25.
Finland, Norway, Sweden, the countries that are way ahead in terms of rolling out heat pumps are the coldest countries in Europe. Heat pumps work very well in cold climates.

It’s important to point out here that in these countries electricity is a lot cheaper than it is in the UK. Unfortunately in the UK the cost of electricity is essentially pegged to the cost of gas. There’s also the feed in tariff charges on electricity, even on renewables, which increases the price. Successive governments have been saying they will look at this and they will do something about it, but as yet nothing has been done. But hopefully, what we call the spark gap – the difference between the gas cost and the electricity cost – will come down in favour of electricity.
For that reason, and for other reasons, the UK is lagging way behind in deployment compared to other countries in Europe.
Are heat pumps new technology?

The reason I’m raising this is it’s a common criticism made of heat pumps: “they’re new, they’re not mature enough technology. So I’ll wait a while longer until they get better”. Actually, they have been around for a pretty long time. It’s just the UK has been slow to catch on to deploying them for heating. Sweden is a very good example of what our Government is currently trying to achieve with the boiler upgrade scheme. The Swedish government set up an equivalent of the boiler upgrade scheme, along with marketing and communications explaining heat pump technology, about 15 years ago. Now half the population of Sweden live in homes heated with heat pumps. So we are behind the curve.
You will be familiar with air conditioning. An air conditioning unit is a heat pump. You can just use it for cooling as well as for heating. There are no radiators attached. It just blows the air into the house, whether that’s warm air or cold air. If you’ve stayed in a hotel recently, the majority of hotels in the UK are now heated and cooled by air conditioning rather than having radiators based on oil and gas. Air source heat pumps are actually everywhere. If you don’t have air conditioning at home, you may well have it in your car – that too is essentially a heat pump. Dishwashers, tumble dryers, even coffee machines, we’re now seeing manufactured with heat pumps in them. Why? Is the obvious question. It’s because of their efficiency – because they hugely reduce energy consumption. It therefore means your dishwasher or your tumble dryer, or your coffee machine is cheaper to run.
Are heat pumps noisy?
I highly recommend you find out for yourselves. There’s a website: www.visitaheatpump.com where you can simply enter your postcode and it will come up with all sorts of properties in your vicinity where the homeowners are happy to show you around and turn the thing on and tell you about living with a heat pump. There’s nothing like the real thing. Do go and listen and have a look.
Just to share my own experience. When we were living in Clun it was a large barn that was converted into three different homes. Two of them had heat pumps and one on the end had still had oil fired heating being off the gas grid. There was only one heating system that we could hear – that was the oil.
Where do I put it?
Connected to the question of noise, and how well you get on with your neighbours. It needs to go outside. As the name suggests, it needs air, it needs air flow around it, behind it as well. So there needs to be a 300mm gap behind it. It could be on a patio, it can go at 1st floor level, you could raise it up on rods, on some sort of frame, or it can go on a flat roof. But do bear in mind you need to be able to get at it, or the servicing maintenance engineer needs to be able to access it. In a flat you may be able to put one on a balcony or an air-to-air system rather than an air to water system might actually work better.
Where will it go? Doesn’t just mean the heat pump. A heat pump or standard heat pumps are not the same as a combi boiler so it doesn’t produce instantaneous hot water. You will need a hot water cylinder to store that water. These modern hot water cylinders are super insulated. They’re wonderful things, but nonetheless they will lose heat, so we would recommend you don’t put it outside in any way. You may be tempted to get it out of the way – put it in the loft, put it in the garage – the recommendation is, don’t. Keep it inside the thermal envelope of the house, ideally in an airing cupboard or a utility room if you have one. Can you build an airing cupboard if you don’t have one? It’s a lovely thing to have, if that’s possible. Hot water tanks are not small. If you don’t use the bath, possibly if you have an electric shower which heats its own water, your heat requirement for hot water is less so you could have a smaller tank.
Do I need planning permission for an air source heat pump?
Planning permission is somewhat up in the air at the moment. Essentially you should be fine under permitted development rights – even if you live in a conservation area which means that in normal circumstances your permitted development rights are removed. They’ve sort of been given back to you because the government is prioritising heat pumps, and they want this rollout to happen. So long as it is to the rear of the property and fairly invisible then you should be okay.
The industry has been lobbying the government saying that the need for applying for planning permission has been putting lots of people off getting a heat pump, so they’ve sought to simplify the rules. Hence the one meter from your neighbour’s boundary rule is being scrapped early in 2025, is what we’re told. But there are other conditions that have been brought in. Visibility from your neighbours is an issue. But what the Government has proposed so far has just caused confusion and disquiet in the industry so further lobbying is going on and really we don’t know where we are at the moment. You’re best off asking your installer whether planning permission will be required.
Will there be lots of upheaval to install a heat pump?
Upheaval is another question that people often ask: “will I have to change my radiators and my pipework?” What are your priorities? That is really the question. If you are after efficiency, maximum efficiency, maximum saving on money to run it, then the more upheaval you can put up with, the more money you will save in the long run. You can make your heating system more efficient by having bigger, better radiators or underfloor heating.
Of course, putting in a hot water cylinder may be disruptive, but if you already have one, and it’s simply a case of taking it out and replacing it with a new one then it won’t be particularly disruptive. It’s very difficult to say how long the whole thing will take because it depends how much work you’re having done and how far you want to take it. Remember, it involves electrical work as well as plumbing so you might well have quite a few people in and out of the house, and it would typically take between 4 and 5 days. But that will very much depend.
Clearly working in retrofit I would recommend you might want to look at what we call fabric improvements before doing this, or at the same time. Improving your insulation and your air tightness is always going to be a good idea but could potentially add significantly to the amount of time and the amount of upheaval. (see Build Tight, Ventilate Right webinar) If your priority is to decarbonise and stop burning gas, stop burning oil, then just get one. Just put one in. That is an option. If you don’t mind a bit of wasted heat or a bit more expense in your electricity bill then there’s no reason not to just install a heat pump right away.
Should you wish to, just another word about underfloor heating. It doesn’t necessarily mean digging up the floor and going down into the earth and having dust and chaos everywhere. I can understand people will possibly balk at that. There’s a wonderful insulation and heating system that lies straight on top of the concrete floor that you’ve already got. XPS boards come in a thickness of about 22mm. Clearly the thicker you go for the more insulation you have, which is better, but if you’re concerned about your head height, you may want to go for a thinner one. That’s a relatively straightforward, non-disruptive option to go for should you wish to, and I have to say I can’t recommend it highly enough. It’s a wonderful thing to have a warm floor under your feet and lovely even temperature across the room. It also saves you radiator space on the wall so you’ve got more space for your furniture and things. One thing to bear in mind, of course, is you would need to have the doors taken off and trim a bit off the bottom to allow for the board and your floor covering. You want a floor covering that will conduct heat so ceramic tiles would be the best way to go.
How much will a heat pump cost to install?
The curiously named boiler upgrade scheme is not about upgrading boilers. It’s about getting rid of them and installing heat pumps. This is a Government grant of £7,500 which is available to everybody. You do not apply for it. Your installer will apply for it for you. You have to own the property so if a tenant wants a heat pump, the landlord can apply for this and make it happen. And you have to have an EPC.
After taking the £7,500 into account, British Gas says they can install heat pumps for £499. For £500 Octopus do the same. It may seem fanciful to you, but it is possible in smallish properties with a straightforward installation where perhaps there’s no radiators to change, just a matter of taking out the boiler and putting in the heat pump, and maybe there’s an airing cupboard already there to put a cylinder into. It can be relatively painless and quick. Dare I say it? Possibly £500. Possibly £1,000 is more realistic in that small home setup. British Gas says the average cost that their customers actually paid a couple of years ago was around £5,500, similar to the cost of my own installation. So that £5,500 – £6,000 perhaps that’s a reasonable guide for not a huge house with not an awful lot being done.
How much will a heat pump cost to run?
I’m afraid this is another “it depends”. I know it’s an important question, but it does depend on who installed it, getting it installed correctly, and operating it correctly.
What well installed means is well fitted by a company who care what they’re doing and take care over it. They do full heat loss calculations, room by room, so that they size the heat pump correctly, and also the radiators or the underfloor heating system if you’re having that. They’ll come back to tweak it if necessary and give you a proper handover so that you understand as the householder how it works and how to control it.
It’s a very different matter from a gas boiler. With a gas boiler we tend to let the property go cold, to turn it off, and then at 4 o’clock in the afternoon, it’ll come back on, and it produces lots of heat very quickly. Essentially a heat pump is simply the opposite. You leave it on all the time and it runs low and slow. You don’t put an enormous demand on it to produce heat very, very suddenly because that’s the way to burn lots of electricity and have a high electricity bill.
The industry is generally saying now that with some basic fabric improvements to the home, so the home is possibly a bit more airtight, a bit more insulated, with a well installed and correctly operated heat pump, it shouldn’t cost you any more than gas heating is currently costing you. And it may even save you some money. gov.uk is currently saying it would maybe save you £100 a year.
Just to explain how this is possible, obviously, we’re a bit scared of electricity because it’s expensive. It’s around 3 times the price of gas at the moment. But if the heat pump is 3 times as efficient, or it could be 4 times more efficient, that’s how it will cost the same, or hopefully, slightly less.
A couple of things that might help: solar panels, of course, are fantastic in general. I’m a huge fan of solar, but using them to run your air source heat pump, particularly in the depth of winter? It’s a nice idea, but it’s not going to happen. There’s not enough energy in the sun.
There are special heat pump tariffs that are now available. Essentially, it means you get a cheaper rate to run your heat pump at certain times of the day. But at other times of the day, typically the peak time in the evening, you pay a penalty rate which is more expensive. I’ve had a look at these, and it seems to me (I may be wrong), what you gain on the one hand you lose on the other. So perhaps not really worth it.
However, the magic is, if you combine one of these time of use tariffs with solar panels and particularly with a battery. It means you don’t have to use the power when you’re purchasing it from the grid. It means you can store it and you can use it when you want to. (See green tech retrofit webinar)
On the Future Ready Homes website (www.futurereadyhomes.org.uk) there’s a case study of a friend of mine who lives in Telford, who has an electric vehicle which means he has access to a very cheap time of use tariff. That means when it’s 2 or 3 o’clock in the morning, and it’s blowing a hooley in the Welsh hills, and the wind turbines are all spinning, lots of power is being generated, but nobody wants to use it. Industry is shut down. Everyone’s asleep. So it’s therefore available very cheaply – about 7p per Kilowatt hour I think currently.
It’s available for you to charge up your EV, but you could also run your heat pump, you could use it to generate hot water so the cylinder is full of hot water for the day, and of course you could fill up the battery so you have it available for later in the day.
Do have a look at this case study if you’re interested, because this chap – who admittedly has a lot of solar panels – his electricity bill, despite running a heat pump, and I think there’s now three electric cars, is negative. Over the year he actually makes money out of the Electricity Company. Which is very nice. If you can. (see the sun king article)
How do I find a good installer?
The future Ready Homes Directory
Heat Geek is an organisation which was set up in recognition of the fact that some heat pump installs are not great, and some installers need some more training. So they offer a lot of training and certification
The Government’s own quality control is the MCS system
How long will a heat pump last?
We are told it should be 20-25 years with regular servicing which would be a little bit longer than a gas boiler. The standard warranty is about five years. You’ll need to keep it serviced, of course, and an annual service will cost you possibly a little bit more than a gas boiler service, about £150- £200.
Heat pump alternatives
A wet heating system obviously refers to a heating system where water is heated up and it goes through pipes to radiators or the underfloor heating. Biomass is an option, perhaps less popular than it was maybe 10 years ago.
If you don’t have such a heating system, then an air conditioning unit (air to air heat pump) is effectively a very good option. It will blow warm air into the property to keep you warm. They’re not particularly expensive, they’re easily deployable, but it does not qualify for the £7,500 boiler upgrade scheme grant, so do be aware of that. And infrared heating is also an option.
I’ll just finish by reminding you: do go out on a visit. Do go out and talk to householders who live with these things.
Dave Green – living with an ASHP
I’ve had a heat pump nearly four years now. I live in a three bed, semi-detached ex council property. It’s by no means a super home: I do have cavity wall insulation, I’ve got double glazing, I’ve got good loft insulation, I’ve done some draught proofing. But it’s still quite a draughty house. And the heat pump works really well.
I replaced some of the radiators, not all of them, just the single panel I replaced with double panel so they don’t take up any more space on the wall than the old ones did. I didn’t bother replacing the radiators in the two bedrooms because we just don’t heat them. I hate a hot bedroom. The ones we’ve got there are perfectly adequate for the occasional time I want to heat my bedroom, and it works. It works really well. I have kept weekly figures of consumption over that period (see three years on living with a heat pump slides)
Generally what you have to look at is the overall – the amount of electricity it uses in a year. My system has been running on an average of around 3,000 kilowatt hours of electricity a year. If I was buying that all in at 25p per kilowatt hour it would cost me £750 pounds a year.
I’ve got rid of gas completely: I’ve now got an induction hob and got rid of the gas fire. So I’m saving £150 a year on the gas standing charge.
I’ve also got solar panels. They provide about 10% of the electricity, maybe 15% of the electricity that the heat pump uses. So it all works. It all works brilliantly, and we’re perfectly warm, and it normally doesn’t make much noise – it does thrum a bit in the coldest weather which we notice a bit more because ours is actually mounted on the wall. But that was that was a space issue.
The one thing is that if you look at the weekly figures, you’ll notice that over those three and a half years, there have been five or six really cold weeks, and in those really cold weeks, if you look at the cost of that week, you would go “Oh, my God! Isn’t it expensive?!” But to counter that, in the spring and the autumn it costs virtually nothing.
So you look at the overall annual figures and don’t get too het up about the odd week when it’s really cold.
I do have a wood stove. I haven’t lit it in 3 years. The house gets too hot.