Solar Thermal Engineers on the Front Line: An interview with plumbing and heating engineer and solar thermal expert, Nathan James Van Gambling (Part 1)

Solar Thermal Engineers on the Front Line: An interview with plumbing and heating engineer and solar thermal expert, Nathan James Van Gambling (Part 1)
Courtesy of Nathan James Van Gambling (From YouTube

Nathan James Van Gambling is a plumbing and heating engineer and lecturer who is also an expert in solar thermal heating systems and energy efficiency and indeed lectures regularly on the subject at industry events such as Low Carbon Homes, as well as producing podcasts. Nathan has a regular presence on Twitter (@betateach) where he discusses these subjects with other heating engineers and solar thermal experts, such as Rob Berridge (@HeatingConsult) and others in the heating industry. For anyone interested in how heating and hot water can be decarbonised and how buildings can be made more energy-efficient, this Twitter discourse surely has got to be a ‘must-read’.

In an in-depth and detailed conversation with Nathan, Robin Whitlock discussed the various benefits of solar thermal systems, how to make energy use and water heating more efficient and why plumbing and heating engineers should be listened to and consulted with far more than they actually are. If we are truly serious about decarbonising heating and hot water, engineers are right there on the ‘front line’, and they should really be brought into play more often.

Note: Because this is a long and extensive interview, in which a lot of interesting ground was covered, the interview has been split into two episodes. Part Two of this conversation will follow along in the very near future.

Can you give me a bit of background about yourself and what you do

So I did a plumbing and heating apprenticeship, my father was involved in heating, he was a technical rep and afterwards went self-employed, but my grandfather, he was one of the European scientists/engineers who helped develop the pressure jet burner. So when oil was the primary fuel before gas, my grandfather was heavily involved with the heating industry. Plumbing is obviously a very old industry, but the heating industry was very new, post war, when we were using coal and oil in boilers. So I went into the industry and followed suit a little bit. I went and did a plumbing and heating apprenticeship, finished off my apprenticeship with the Ministry of Defence (MoD) on a military airbase and went into teaching in 2006. I started teaching adult learners in a prison, really enjoyed passing on knowledge and so stuck with it, taught in a few colleges. I then realised that social media and digital media was coming more to the fore, in all industries really, so I side-stepped from teaching in a college about a year ago to build upon facilitating learning but using digital media technology to do that.

Can you tell me a bit more about solar thermal and its potential, particularly with regard to decarbonising heating and hot water?

Basically, water, and I am not sure if this is a widely known principle, but water is extremely energy-intensive to heat up. It is the most energy-intensive common substance to heat up and there’s probably only a few substances or elements that have a higher specific heat capacity than water. It’s so energy-intensive to heat up, that’s why we use it to keep things cool, so we keep nuclear reactors cool with water and we keep engines cool with water. We obviously live in a world now that has changed within a generation, with regard to how we use water to sanitise ourselves, I mean if you go back to my age-group, you had one bath after your football game on a Saturday and then you flannel washed during the week to go to school. Plenty of people now are having three hot showers a day.

Solar thermal works on the premise that, well, when people think of solar they think of PV panels, and we’ve obviously got millions of them on the roofs in this country. PV panels are brilliant, they produce electricity, but they use the visible light to do that. Next door to visible light on the electromagnetic spectrum is infra-red. Even though we can’t see it, it is there, and we can heat water up with it and you can do that quite successfully for a good number of years. It came over to the UK from the US perhaps in the seventies, but was very, very minimal. In the nineties, it started getting a foothold, didn’t really see much success, but if we’re going to heat water, it’s totally clean and free. I think it’s the fact that it’s free that has actually stifled it somewhat, and I might be being a bit cynical here, because no-one can make money from it. It is an off-grid technology, so I think the government has steered more towards PV, which puts electricity into the grid which can then be bought back. Solar thermal is an off-grid technology, so it’s great for the homeowner and great for district heating systems. It’s taken off in Europe a bit now, but it seems to be lagging in the UK – you can do a Twitter search on climate change and you hardly hear them talking about it at all. If they do talk solar, they talk PV.

The other miff we’ve got is people thinking that if it’s a cloudy day or it’s cold you can’t get heat from the sun. That’s nonsense. You can have a solar thermal system in the Antarctic and you can still boil water. When you walk out your door, even if it’s cold, wet or windy, you can still see because you’ve got the visible light spectrum. It’s exactly the same – you’ve still got “infrared”. The irony is we’ve got a whole world going hysterical about the greenhouse effect, which is obviously the gases trapping infra-red and stopping it getting back to space, and yet we’re not utilising that same principle of trapping the infra-red, which you can do with evacuated tubes. An evacuated tube is basically a little bit like a thermos flask in that you have two glass vessels with a vacuum in between so that the infra-red goes through but can’t escape and it just keeps heating and heating whatever you want to heat inside.

It’s a big shame, especially with new-build. All new-builds should really be designed with solar thermal. That’s a complete no-brainer because at the planning stage, the design stage, you’ve got a blank slate to do what you want. Solar thermal works well with heat pumps, because rather than it being there in the ground, as in a ground source heat pump, it’s there in the water that’s being heated by the solar thermal. We also have PVT systems now (photovoltaic thermal). PV panels can get very hot and the more hot they get the less efficient they get. Ideally, you would water-cool them, and that’s what we call PVT. That’s been incorporated in Europe a lot. I think there’s just been a hotel that’s been fitted with PVT panels and it produces all its electric to power the heat pumps and the water that’s cooling the solar PV panels is the warm water that the heat pumps are using. It’s quite a lovely self-sufficient system and they produce over 100 million litres of hot water a year, free, with no carbon dioxide.

That’s a question I was going to ask a bit later, but I’ll get straight on to it now – what’s the scale of the problem with solar PV losing efficiency when they get really hot?

That’s just physics. When they get warmer they lose the ability to produce electricity, they still work but they become less efficient the hotter they get. A company called Naked Energy install PVT systems, so you are producing electricity with the same square metres as you would with a normal PV panel, but you’re keeping it cool, keeping it water-cooled. Then you use the water that you’re keeping the PV panels cool with, that water’s obviously getting warmer and warmer and you can use that water to power your heat pumps. It’s a bit of a no brainer really for new builds, but we still seem to be in the steam age – in that we use nuclear power to heat water to drive turbines to create electricity, we use gas in gas power stations to heat water up to produce steam to produce electricity, so we’re still in the dark ages and steam age in a lot of respects with a lot of the technology.

So why do you think it is that the government isn’t doing this? Is it just because it doesn’t make money as you said a moment ago?

I don’t know the machinations of government, I don’t really know how they work, but I do know that you have lobbyists that will lobby our government and try and implement certain measures, so if you look at the heating industry, the industry in the UK does have a system where it will lobby government to initiate policy and incorporate strategies that they think will solve the climate change problem, but they are always, and I suppose this is the same with any industry, be it the food industry or the soft drinks industry, they are always going to be coming from a position that benefits them. So if you look at the heating industry in the UK, it’s a very new industry, say 1967 when gas became the primary fuel. It was massive. Up until 2016, the UK boiler industry was the biggest boiler industry in the world. It’s now the third biggest I think, Korea and America are now first and second, but half the boilers that are sold in Europe are put onto UK kitchen walls basically. So we’re still a massive boiler market, we’re massive key players, we’re a saturated boiler market due to lots of boiler companies that have a world presence, like Vaillant, the biggest in the world, probably No2 in this country, Bosch is No1, but you’ve got another 20, 30, 40 boiler companies. So it’s a very oversaturated market.

I think what is happening now is that they are actually some of them going direct to government rather than going through the HHIC. The Heating and Hot Water Industry Council is the umbrella for lots of organisations and trade bodies like the Bathroom Manufacturers Association, a load of them, about 15 of them. The HHIC is actually under the Energy Utilities Alliance. If you look at the Energy Utilities Alliance website, actually I think it has changed since they went on social media and some people made some remarks, but one of their key mandates is sustainability. Now obviously, if you hear of that word, you think of something environmental, but fundamentally it is about sustaining the boiler industry.*[This is Nathan's own opinion and should not be interpreted as fact. Please see clarification note below] The boiler manufacturing industry is a big lucrative industry. I mean they sold about £20 billion worth of boilers in five years.

Thermaltricity thermal store for use with solar thermal systems, designed and installed by Eric Hawkins (Image courtesy of Eric Hawkins)

When condensing boilers came out, convection technology has been around a long time, but when they really pushed it forward in this country and the regulations changed in 2005, where if you were installing a boiler it had to be a condensing boiler, they are efficient, don’t get me wrong, the way they work is efficient, but we sold, between 2005 and 2010, which was a big push of getting condensing boilers into the UK, we sold about £20 billion of them. Now most of them would have been ripped out by now, because the biggest problem is we’re putting in efficient boilers on to dirty, old, systems. Some people blame the engineer, but I don’t blame the engineer. I blame the industry, because it’s just been so fixated promoting sales of boilers, it hasn’t really engaged over training, I mean you could go and become gas safe in a month, you could become oftec in seven days. Of course, what happens is, because as I say plumbing is a very old industry, and in the 70s most plumbers would have been employed by the council or the big companies, and as we moved into the 80s and 90s, 80 percent of plumbers are now self-employed. What’s tended to happen is that the boiler companies have become so powerful that if you’re a gas engineer, you’re now an ‘elite’ engineer. That kind of used to be the case, but what’s happened now is that it’s so easy for people to become gas safe or oftec registered, once they’ve got those digits the public think they are the elite and yet a lot of them don’t know that much about heating systems or about plumbing regulations. Some people say the problem is the engineer who goes on these fast-track courses. I refute that. I say it’s the industry’s problem because they’ve been so fixated on marketing, the boiler tech needed. I don’t blame individuals, the individuals are fantastic, it’s the industry that’s gone off track a little bit.

I think it’s starting to listen though because historically engineers have never had a voice. You had trade media magazines who pushed out the latest advertorials for the PR companies that work for the boiler industry and you had the Letters page, and that was the only page really that me and my dad was interested in reading, because it was listening to what other engineers were encountering, their problems. Social media has now built on that. You have a reciprocating voice, so engineers are now starting to be listened to and disseminate good information. The world’s all listening to scientists at the moment regarding climate change, but of course the engineer is the one that is actually at the ‘coal face’ of this technology. It’s all very well someone jumping up and down saying “heat pumps are saving the world”, but a lot of the time they won’t, and it’s the guys who are working with this technology who are giving us all indications of what works and what doesn’t work in certain situations. There’s not a one-fix solution because our houses are now so diverse.

So you were talking a little about this on Twitter, to the effect that plumbing and heating engineers are in a really good position to influence and enable decarbonisation, so to what extent do you think that the government and powers-that-be are listening to engineers on the ground?

I think it’s a very new era, I am quite optimistic because I do believe we are living in an unprecedented ‘golden age’ of communication. It’s never happened before. Social media is relatively new and although there might be a bit of banter and a few spats, the undercurrent of it all is that engineers have always had lots to say and discuss. They were doing that in coffee-houses in the 1600s. They’ve always met up and chatted. Your average painter or carpet-fitter, great skills don’t get me wrong, but they haven’t really got a lot to chat about outside what colour your bathroom or carpet is. Whereas engineers, the heating engineers, well, all engineers, have just got immense amounts of information to chat about and everyone’s learning off each other. No-one knows it all, but we’re all disseminating scenarios which are reciprocated and we’re all learning so much off each other.

I think the industry is listening, they’re definitely monitoring people like me and Rob Berridge, who’s been running this campaign regarding the fact that 90 percent of our boilers are oversized. Your average house in the UK just needs a heat demand between 6 and 8 kilowatts. The irony is that when we teach these, let’s say I am teaching Level 3, we teach them how to perform heat loss calculations. We use a book called the Domestic Heating Design Guide but it’s like the Bible for designing heating systems. It’s endorsed by CIBSE, Associated Heating Company, Chartered Institute of Heating Engineers, the Underfloor Heating Manufacturers Association, Hot Water and Heating Industry Council, it’s endorsed by all these people, yet in reality, in the real world, if you’re teaching students to do a heat loss calculation coming out at 8 kilowatts, the smallest boiler anyone can buy is around 24 kilowatts.

The boiler companies are coming back at us because they realise we are making a bit of noise about this, and they are saying we can modulate down the gas valve, which you can, but in principle it still isn’t giving you the best efficient system because the actual heat exchanger is a 24 kilowatt heat exchanger. It’s a lump of metal that was designed to be able to heat up and be that powerful. So the boiler manufacturers are obviously market-driven, but they have smaller boilers on the continent, but of course the market over here is different to that on the continent, many people live in district housing on the continent, so it’s different, but over here we went absolutely hysterical and crazy with the combination boiler, which is suitable in some instances but in a lot of instances it isn’t.

Going back to training, if they go on a fast-track course, all they really know is how to change over a combination boiler, and that’s not efficient, the fact that they break down so quick, they’ve got lots more parts in them, the industry is listening and monitoring, but doesn’t know where to turn I think. In any one big corporation or big company, it’s very unlikely you have just one person that has the say, with regard to what to do, I suppose it’s people who are not that willing to put their head above the parapet. Worcester Bosch are definitely monitoring this thing about boiler size because they did an article in HVP last month, with Martyn Bridges, (Director of Technical Communication and Product Management at Worcester Bosch), and he was kind of making it out to be a bit of a nonsense that we need small boilers, but of course we need small boilers. He then got a reply from Rob Berridge, but three paragraphs were cut. So unfortunately, the trade media, as much as I like the editors, who are often young and bright and very passionate, they are not in the industry, but just learning about it. They went to media school, lovely people, but of course people are paying them, that is all the advertising from big companies, so we rely on digital media, the podcasts and so on. I want to do more on solar thermal and get a wider audience, people who are really interested in climate change. The heating industry and the transport industry definitely have a major role to play, transport is probably a bit simpler, but the heating industry is so complex the homes and dwellings that we all live and work in.

So how easily could boilers in residential properties be switched over to solar thermal systems?

In a mechanical sense, relatively easy. It’s the mindset of people now. We have got a mindset of consumers that are so used to their combi boiler, they wouldn’t want you now reinstalling a cupboard that had a cylinder in it. Solar thermal panels work very well with thermal stores, that’s where they store the energy. They do work with cylinders as well, so in the 1990s we kind of adopted the German way of doing it, so we had solar thermal panels on the roof and they heated up a cylinder. This cyclinder is what we call an unvented cylinder and you were only ever heating up the domestic hot water demand and if you had a couple of baths it would use up all the hot water and it would take the rest of the day to heat it up again. With a thermal store, you are heating up a slightly larger body of water and storing it at a hotter temperature. So if you imagine, you’ve got the solar thermal panel on the roof, some pipework that flows into the store and directly out of the store, back out to the solar thermal panel. In that store, you’ve got a coil. The cold main goes in at the bottom of the store, around the coil, so it’s not actually mixing with the dirty water in the store, goes around the coil, picks up heat and comes out hot. You can produce a lot more domestic hot water that way.

The other advantage of a thermal store is you can use that water that’s been heated by the sun to go into your underfloor heating or in your radiators. In the 1990s, they didn’t allow us to do that. They came up with a few excuses to try and make it sense, but the other problem with the German method being adopted was that you would use glycol, you would put glycol in the system. Now unless these systems are being maintained regularly, so that every three years you would have to change the glycol, otherwise it turns into something like tar. What was also happening was that the trade was starting to slowly be devalued by it being so easy to get into the trade. You would have people who were combi gas trained, used to working with a combi boiler and seeing these systems and saying “well, I don’t know what this is” and they would rip it out and put in a combi. So a lot of those systems in the 1990s never had the maintenance they needed or the skillset to maintain them. In Germany, the mindset of the consumer is totally different, so engineers in Germany are highly valued. By law for instance, if a heating engineer, especially a chimney engineer, rang you up and said “I need to come around yours tomorrow to service the boiler”, by law you would have to have someone at your house to let that heating engineer in. The mindset in the UK isn’t like that. So they have quite a good maintenance regime.

But these systems, we don’t actually need those German systems. The open-vented thermal stores don’t need glycol, don’t need maintenance – the one I installed for my friend, that one will go for thirty years without you even needing to look at it almost. So, in one sense it would be easy, but people have become very precious of their space in their homes haven’t they? So the idea that they would get a thermal store and have to put it somewhere – I mean you can put it in the loft if you want – that’s not attractive to people anymore. It’s the same with heat pumps, they are great big things, and you have to put them somewhere. Obviously with new-builds it’s a no-brainer – you can factor that in at the planning stage. So you’ll get people who understand the benefits of solar thermal and don’t really mind – you’re talking the same kind of size as the cylinder that people used to have in their airing cupboards, but within a generation now, you’ve got people who are more used to having boilers within a kitchen cupboard. That’s caused problems in itself as well.

I am quietly optimistic about young people though. Young people are getting technology, they like technology. They like the idea of it being a bit new, a bit different, utilising common-sense principles, and mindsets can change quite quickly in the populace.

Do watch out for Part Two of this highly interesting conversation, which will follow along very shortly....To be continued.....

*[Please Note: Given that this is an interview article, Nathan's statements presented here are purely his own opinion and do not necessarily reflect the views of Renewable Energy Magazine or any persons employed by or associated with it.

Since this interview was conducted, the Energy Utilities Alliance (EUA) have asked us to clarify various points, clarifications which we are more than happy to publish. They are as follows:

Contrary to the beliefs expressed in one particular paragraph of this interview article, the Heating and Hot Water Industry Council (HHIC) have no affiliation with the Bathroom Manufacturers Association (BMA). Furthermore, HHIC is not an umbrella organisation.

The content presented on the website of the Energy Utilities Alliance constantly changes in order to reflect current work and industry/government issues.

Nathan's statement that the word 'sustainability', as used by the EUA to describe one of their policy mandates, is really about sustaining the boiler industry, is his own opinion and should therefore not be interpreted as fact. However, this final point does indeed reflect the fact that there is currently some difference of opinion between some heating engineers and the wider industry, particularly some industry trade associations, with regard to the degree to which some boiler manufacturers are able to influence the industry, and government, with regard to whether or not, or how rapidly, solar thermal technologies could or should replace gas central heating. Indeed there seems to be considerable consternation expressed about this particular issue between engineers on the ground and the industry. Given that, currently, the UK is falling behind on its 2020 renewable heat targets, this is clearly a matter of great relevance and significant interest to anyone supporting the transition to renewable energy technologies and therefore may well be worthy of further investigation in the near future.]  

For additional information:

Nathan James Van Gambling (LinkedIn)

Nathan James Van Gambling (Twitter - @betateach)


“Talk of the Trade” with Nathan James Van Gambling (YouTube)

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