Earth Notes: KEHS talk: The Truth About Heat Pumps (2024)

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Okay, hello everybody. We installed a heat pump, well it's nearly 15 years ago now, so we were

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distinctly early adopters of this, and it was really part of a project to try and reduce our carbon footprint, so no calculations about payback period or anything like that.  I divided it into "What is a heat pump?" ... there is so much

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misinformation and disinformation around heat pumps, just try and get everybody on the same

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same place. "Our experience with owning and living with one of these things for 15 years" and then "Why

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heat pumps are necessary" really for the country, not just for individuals, so a heat pump. Okay,

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well most people are absolutely shocked at this price and really when you start to look into them

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they are extraordinarily complex engineering devices, much much more complicated than a boiler,

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stuffed full of electronics, compressors, heat exchangers, all sorts of things and you think

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they're very sort of new things but they're not. The first heat pump was made in 1830, well before

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anybody thought about gas boilers. You all, each of you, probably has three heat pumps, maybe more.

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You've got one in the fridge, one in the freezer, one in a car, you might have an air conditioning

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and you might have dehumidifiers. They are everywhere, it's very common technology now, but

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complicated. Basically what it does is that it pumps heat backwards against temperature. I mean

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you'll think about your fridge, this is what happens, you know, your fridge, you're making a fridge

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and the fridge keeps on pumping it out and dumping it back in the kitchen and it's just going round

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and round in circles and that's what heat pump does. It needs some electricity to work because

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a gas boiler, the gas boiler or electric heater, you buy the electricity or the gas, you put it in,

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that's got the energy in it and you release it as heat. So you take the chemical energy in the gas

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and convert it into heat energy, um, the efficiency is maybe 80 or 90 percent, some of it's waste,

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some of it goes to the gym and that's fine. With a heat pump, you're not actually converting one

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form of energy to the other, you're harvesting energy in the environment and pumping it into

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your house. It takes some energy to run the machine and that energy is not wasted, it is, most of it is

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retained in the system, so it's not wasted energy, um, but the efficiencies are huge because it's,

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instead of being saying 90 percent for a good gas boiler, it's 300 percent for a heat pump,

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so it's harvesting three times as much. Now, when I sort of mentioned it, everybody said,

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well what happens on a really cold day when it's freezing, surely there's no energy left in the air.

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Um, well there is lots of energy left in the air, um, you have to think that there is no energy

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left in the air at minus 273, which is absolute zero. Now, you wouldn't exist in that form at

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minus 273, but if you think that you're, the environment we live in, it's maybe, you're going

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to be using a heat pump from when it's about 10 degrees to minus 5 degrees here, and the change

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in energy in the air over that range, tiny. The temperature difference does affect the heat pump,

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but it doesn't affect the principle of there being lots of energy in the environment to be harvested.

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So these are strange devices, um, very reliable, established technology. We went for a heat pump,

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your house. I thought, well okay, so we better check this. So we went to Daikin's training

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centre in Woking, where they got lots and lots of heat pumps, and we heard them. They sent them

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running, and we listened to them, and we thought, well okay, they're not silent, they make a noise,

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and it's probably a bit noisier than the flu on a gas boiler, because gas boiler makes noise,

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um, but it's okay, it's going to be okay, or we can live with it. And anyway, what's the equation

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between climate change and a bit of noise, why these two equated, I don't know why they equated,

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but people do. It was installed, um, we were the first customers in this company, and it showed they,

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um, we had three guys. We had a guy who dealt with refrigerants, a guy who dealt with electrics,

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and a guy who dealt with plumbing, and they were very good, but they never done one before,

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and they fled after they'd fitted me, and left me with a manual. This, they translated from

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Korean, I suppose, and my first was like, how on earth can they sell these to the general public?

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You have to be, I'm an engineer, and I have to be an engineer really to cope with this. I find it

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very stressful, very difficult, and I find faults, and they have to come back, and you know, I had to

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commission it and get it running, but we've got it settled, and I think if you went to Octopus now,

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who are the big sellers of them, it will be absolutely fine. Okay, it's been reliable,

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it had its first fault a couple years ago. In fact, it was a trivial fault. It took quite a

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lot of money to fix it, because the diagnostics in the machine are not brilliant. Ours is a very

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early one, and when it came out with its error code, and I phoned Aiken and said this is the

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error code, and he said, oh dear, that one covers a whole lot of faults, and we can't really tell.

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And so they changed lots of parts, which they didn't need to change, but I think machines,

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you know, it's all got better now. It was really just a solenoid that got a bit sticky, and it

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actually went into, like cars do, a limp home mode. So it carried on working, so this was in mid-winter,

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but it carried on working, not very well, but it kept our house warm over that time. So, and I have

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its checked every year, it doesn't really have any requirements for servicing, very, very simple.

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And the people who come and service it, they're really, they're absolutely excellent people.

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That was cost, well, in 2009, cost 12,000 pounds, so very expensive compared to gas boiler

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at the time. This is the crux of it, really, a graph of the efficiency and how the efficiency

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varies with the temperature of the water. Because it really is just a straight replacement for a gas

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boiler, in our case. So it connects into a hot water regulator system, which I've come on to,

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and the vertical bit is the efficiency, and it goes from four times to two times. So 400% efficiency,

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down to 200% efficiency, and this is the difference in temperature between hot water in the radiators,

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so that's what it's producing, and the temperature outside, because the temperature outside

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affects how it works. And what this means is on temperate days, when it might be seven degrees

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outside, and you want to heat your house to 20 degrees, and you might need water in the

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five, and you want to get water in the radiators up to 50 degrees, the efficiency drops. So the

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efficiency of it is changing rapidly all the time. It's not like a gas boiler, which is pretty

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constant. This is dynamic. It's moving around the whole time, depending on how cold it is outside,

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and how warm the radiator needs to be. So with this sort of thing in mind, you need to really

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try to get it to run as cool as it can all the time. So it's not like a gas boiler, which is

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blast water, hot water at 70, 75 degrees. Shouldn't really do this, but they do. This you need to

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always think about getting the temperature of the water down as low as possible, because the

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efficiency rockets you do that. And this I think this is why, you know, there's so much criticism

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in the press of people finding fault is because they haven't been installed with this in mind.

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The temperature of the water has to be as low as possible. And if you lower the temperature of the

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water and the radiators, the output of the radiators goes down more rapidly than the

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temperature that goes down. It's not linear, so it can go horribly wrong if you don't get it right.

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And there are two ways of addressing getting the temperature down. One is you improve the efficiency

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of the insulation in your house, which you might or might not be able to do. And that people say,

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you know, insulates your house. Well, okay, but you can put some loft insulation in, you can put

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some better windows in, some draft proofing around the doors. And then it starts to get difficult.

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insulation, but if you've got an old house with solid brick walls, it becomes very expensive.

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It's a Victorian house, you start to change the character of the house if you put it on the outside.

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There's just a heat pump. It's an easy fix, really, because what you do is you reduce your energy

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consumption three times. And there's no insulation, which you can do to a Victorian house, which will

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get anywhere near that. And if you did try it, it would cost you hundreds of thousands of pounds,

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you know, make sure you're loft insulation, fine, make sure you've got the windows draft proofing,

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maybe you can seal the floor. So you haven't got lots of drafty floors, and then stick a heat

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pump in. That's the best thing. There are settings in our machine, which you have to go in and set.

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I'm not showing the installer should do this is where you actually set the temperature in the

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radiator to be dependent on the temperature outside. So on really, really cold days, our

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radiators are about 50 degrees, maybe that's 49. And that's as hot as they go. And then as we come

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into this time, well, it's not on now. But you know, a few months ago, when it was maybe 10 degrees

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outside, I would have the temperature and the radiators about 2022. And what that does is

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because the pump's compressor now doesn't have to work so hard, because he's not having to produce

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very hot water. The electric demand drops and the efficiency rockets. And this is what we did, we

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put in bigger rate, we had steel radiators. And at the time we did this the best way, because

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everybody has a problem, they have pipes coming up to the floor, and what are you going to do to tear

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up the floor to put in bigger radiators. So we went for fitting radiators to the same pipes.

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And we went for cast aluminium radiators. So instead of having a steel panel radiator,

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we put in cast aluminium radiators, which is like this and this, which have much higher output.

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Basically, you need to be doing something like increasing, well, it depends on what you've got

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in the house, but you may be looking to increase the radiator outputs by 50 to 70%. Something of

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that order is likely to work. If you take a radiator, steel radiator, which is designed to

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work with water going in at 70 degrees, and then you then change that and put water in at 50 degrees,

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the output of the radiator will be hard. Now, since we did this, which was obviously 50 years ago,

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Stelran, who are the big manufacturers of steel radiators, now produce a radiator, which is

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designed to go onto the existing pipes and have twice the output. So they have actually solved

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this problem, but we didn't have that choice. So on our pipe, you can probably see just about,

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there's a sort of conch of botch pipe workers, the plumber, the pipes didn't quite line up with

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the size of the radiator, and the plumber had to do with the chicken was around.

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You wouldn't need to do that nowadays. So one of the things, if you can add insulation and reduce

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the heat loss of your house by doing that and draft quickly and get that improvement,

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sort of reducing airflow, sweeping heat out through the house, you might reduce, say,

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the heat demand of the house by 10%. If you could do that with a heat, if you do that with a gas

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boiler, you can just save 10%. If you do it with a heat pump, what it means is you can take the

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opportunity to lower the temperature in the radiators because you no longer need so much

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heat flowing into the house. You lower the temperature in the radiators and the efficiency

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goes up. So you probably save 15%. Our energy bills are energy consumption normalized. It's

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about 50 kilowatt hours of energy. This is everything we use. So I can't separate out

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televisions left on standby and all this sort of stuff, because we just can't be bothered to sort

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that out. It's about 50 kilowatt hours per square meter. And UK norms are 150 to 300 kilowatt

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hours per [square] meter, maybe more, depending...