SimonD

I think you've still got a good couple of weeks to go at least until the system balances itself out. I would just go weather compensation, fully in the knowledge you'll be tweaking it for the next couple of months.. The problem I've found with running elevated WC with a thermostat is that they can end up fighting each other, especially if the thermostat has modulating input to the heatpump & flow temps. You then get oscillating compressor frequencies and can even see elevated defrost cycle frequency. Obviously this depends on how the controls are designed and implemented. If you go weather compensation only you're reducing your variables and any diagnostics/analysis of system behaviour becomes a lot easier.

I thought I might pop this article from 2013 in here. It deals with almost every question that's been discussed on this thread, apart from a significant reduction in energy consumption. But despite the progress, it also highlights how little has changed: (link to article: https://www.resilience.org/stories/2013-02-27/can-we-live-again-in-1964-s-energy-world/) Can we live again in 1964’s energy world? By Andrew Nikiforuk, originally published by The Tyee February 27, 2013 "Everything has to get worse. We are behaving so badly." Vaclav Smil, you should know, talks very fast in staccato bursts and doesn’t own a cell phone. The University of Manitoba professor, perhaps one of Canada’s most precise energy analysts, also doesn’t want to be the servant of a communication machine. "Everyone wants a piece of me," he adds. Authorities from China, Japan, Russia and the United States pester him with speaking invitations and information requests all the time. Even Microsoft billionaire Bill Gates makes demands on him. And that’s because Smil actually knows something about energy in a world that has grown largely energy illiterate, thanks to a now threatened diet of cheap hydrocarbons. For nearly 40 years now, Smil, a Czech émigré and polymath, has studied the world’s energy systems. He grew up in the political darkness of the Soviet Empire and has matured in the moral emptiness of its American counterpart. Although heralded around the world for his insights, he remains largely unknown in Canada. Yet the prolific academic has penned some 30 books and 400 articles on how the world recklessly spends both energy and valuable natural resources. All of Smil’s work is dense, number-filled, literate and chock full of intriguing history. Altogether, his energy writing delivers a sober two-pronged message: North Americans have grown fat and lazy by burning too many fossil fuels. Yet energy transitions are by their very nature protracted, difficult and unpredictable. Wood to coal Although oil shocks and boomtowns can unsettle economies in just years, real energy transitions in large global economies often unfold over decades if not generations, Smil observes. Take one of the world’s first major energy transitions from wood to coal as a source of heat, he says. At first aristocrats considered coal a foul and smoky substitute for wood. But a tree famine in northern Europe and England forced along the hydrocarbon’s adoption by the 17th century. It really took the invention and deployment of the steam engine to transform coal into an empire builder. Even so, coal didn’t provide the world with nearly 90 per cent of its primary energy until 1930 before being partly replaced by oil. So transitions take a long time. "The 19th century was a wood century and the 20th was a coal century." Oil didn’t reach its peak as central energy source until the 1970s and still accounts for one-third of the world’s energy needs. In fact, the global economy remains a full-blown fossil fuel civilization that mines coal, oil and natural gas to satisfy the majority of its energy diet. Even the transition from horse to car took a long time, adds Smil. In 1885, Gottfried Daimler built one of the world’s first combustion engines. "Thirty-three years later the number of horses in the world peaked and then the transition went very fast." But it took 50 years to remove the horse from urban streets and farms. Energized all the time Our overwhelming dependence on fossil fuels creates another problem. In 1850, the average European or North American used energy intermittently. You’d put the fire on in the morning, harness a horse or roll up some sails, says Smil. Energy use was organic and the night skies often fell dark. Today people use energy 24/7 and at fantastic levels. Every home plugs into an ever-increasing number of glowing gadgets, each promising more comfort and entertainment than the last one. "There are no peaks and valleys. It’s not just the quality but the constancy of energy use that has changed," explains Smil every so quickly. Now don’t get Smil wrong. He thinks modern societies consume way too much energy (North Americans consume twice as much as Europeans and yet aren’t twice as smart or happy, he adds sarcastically). Moreover, we lavishly waste much of it on the overproduction of cheap and unnecessary junk. He believes a transition to "non-fossil future is an imperative process of self-preservation" as well as a moral necessity. Harnessing renewable energy flows, is both desirable and inevitable, he adds. But the old-fashioned engineer and historian doesn’t think the transition to cleaner forms of energy will be easy, quick, rational or smooth. That’s a lot of exajoules One of the first obstacles is just the amount of quantifiable fossil-fueled power that must be replaced. Consider, says Smil, that North Americans gobbled up about six exajoules (EJ) of energy in the form of wood, animal power, coal and some oil in 1884. (The Japanese earthquake and tsunami released about two EJ of energy.) Today North Americans happily burn our way through 100 EJ of which only 7 EJ come from renewables, such as hydroelectric dams. In other words, the U.S. would have to find 85 EJ from wind, geothermal or wind or "nearly 30 times the total of fossil fuels the country needed in the mid-188s to complete its shift from biomass to coal to hydrocarbons." That’s a tall order requiring new infrastructure and massive re-engineering. The second issue for Smil is capacity. Renewables such as wind and solar just don’t have the same ability to make concentrated energy as fossil fuels. Capacity is the constancy of energy that an electrical power plant can actually deliver divided by what it could produce if it operated 24/7. No power plants, of course, work that way. Nuclear plants, if they are not leaking or down for repairs, can operate 90 per cent of the time. Coal-fired plants can chug along 65 per cent of the time before they need to be cleaned and repaired. But a solar installation can only pump out juice 20 per cent of the time. A wind farm can muster power 25 to 30 per cent of the time or slightly more if perched offshore. Next comes power density. It’s the rate of flow of energy per unit of land area. A coal mine or oil field can deliver great power density. So, too, can a hydroelectric dam. But not renewables. Fossil fuels, despite their declining quality, still offer power densities two to three times greater by orders of magnitude than wind, biofuels or solar. Smil then offers an uncomfortable calculation. In the early years of the 21st century, the fossil fuel industry (mining, processing and piping) occupied 30,000 square kilometres, or an area about the size of Belgium. The low power densities of renewables, just to replace one-third of the demand for fossil fuels, would require a land base of 12,500,000 km for turbines, solar arrays and transmission lines. That’s a territory the size of the U.S. and India. Renewable challenges To Smil each renewable or alternative to fossil fuels offers a unique challenge. He thinks that solar, of all renewables, offers the greatest potential. It’s the only alternative that currently delivers flows of energy that readily surpass the demand for fossil fuels. But capturing and transporting those flows at the right commercial scale still proves elusive. "We don’t yet have the storage capacity. Solar energy works only when the sun shines." Nuclear, he says, is "as dead as it can be." It promised cheap energy but delivered the world’s least economic source of power as well as persistent waste issues. Only Alberta wants to build nuclear reactors to manufacture more bitumen, a proposal he calls "madness incarnate." Wind will require millions of turbines and massive land disturbance that may be "environmentally undesirable and technically problematic." It’s also an intermittent source of power that requires extensive back-up, usually in the form of coal-fired stations. And in large parts of the world the wind simply does not blow regularly. Biomass or growing modified trees, sugar-rich crops or algae to fuel inefficient vehicles poses another problem altogether. Civilization has already appropriated 40 per cent of all plant growing activity on Earth for food, fibre and feed. This appropriation has already modified, reduced and compromised ecosystems to "a worrisome degree." Devoting more the world’s precious soils to produce something like ethanol, says Smil, is "stupid." Refashioning a ‘supersystem’ The engineer’s bottom line is sobering, if not completely politically incorrect. Over the last 100 years the world has spent trillions of dollars building the most extensive energy network ever conceived. Millions of machines now essentially run on 14 trillion watts of coal, oil and natural gas. The quality of these fuels is declining, and keeping the whole show going is getting more and more expensive every day. Refashioning what Smil calls the world’s costliest "supersystem" into something cleaner and sustainable will be a gargantuan task that requires "generations of engineers." "Yet everyone is broke. So how are we going to build hundreds of billions worth of solar and wind farms?" To Smil the only moral response remains a "significant reduction in fossil fuel use." The scientist proposes going back to the future — or the 1960s, to be precise. "In the 1960s people didn’t have three car garages, fly to Las Vegas to gamble or drive SUVs, but they lived comfortably," says Smil. More importantly, they consumed 40 per cent less energy than people today. "We can return to 1964 with no problem. Living in 1964 is not a sacrifice." Nor would getting there impose draconian challenges. Switching to 97 per cent energy efficient furnaces (that means they burn 97 per cent of the gas instead older varieties which send 55 per cent up venting stacks), mandating diesel-fueled vehicles and deploying high speed trains would all be part of the solution. "Bombardier makes rapid trains in this country," declares Smil. "Yet there is not high speed train between Montreal and Toronto. Canada doesn’t have a significant high speed link. It’s incredible!" ‘It will have to collapse’ Smil recognizes that reduced energy use is not yet seen as desirable or politically unacceptable but "replacing entrenched precepts," he adds, is never easy. In the absence of "radical departures" from that status quo, Smil sees but one all-too human reality: "Everything is going to have to get worse." That seems to be the global course at the moment, as oil dependent jurisdictions such as Japan, North America and Europe pretend their "overdrawn accounts, faltering economies and aging populations" don’t exist. Smil, for example, regards China’s rise as an industrial and authoritarian superpower as a copycat of the worst excesses of the U.S. energy experience. To Smil, a long-time opponent of the Three Gorges Dam, the Chinese may well outdo Americans in gratuitous materialism. "China will speed the day of reckoning and India is coming next," he says. He calls the new fossil fuel gobbling economies "riders of the apocalypse." Their energy ascent is physically not possible without an energy descent in the developed world, explains Smil. "There is no shortage of delusionary people," adds Smil. "I’m a stupid, old fashioned 19th century engineer. Things move slowly." In fact, no society has really begun any transition other than that of collective global economic stagnation and accelerating investments in fossil fuels. "Americans are living beyond their means, wasting energy in their houses and cars and amassing energy-intensive throwaway products on credit," he recently wrote in Foreign Policy magazine. Yet no U.S. politician has yet advocated a reduction in fossil fuel energy use by 40 per cent even though avoiding catastrophic climatic change now demands such behavioural changes. "We will never act voluntarily. It will have to collapse. That’s optimistic," he quips. You know, he repeats, "Living in 1964 is not a sacrifice." The conversation ends. Another investigator wants to pump Smil for more straight energy talk. But perhaps his best advice still remains the concluding sentence of a 2011 article in American Scientist: "None of us can foresee the eventual contours of new energy arrangements — but could the world’s richest countries go wrong by striving for moderation of their energy use?" Next Wednesday in Andrew Nikiforuk’s ‘The Big Shift’: What drove our last big shift, from horsepower to steam, and upheavals it caused. MANY DOWNSIDES TO HIGH ENERGY SPENDING Vaclav Smil, one of the world’s greatest energy analysts and thinkers, has long argued that the key to managing energy supplies is to consume less energy, not more. The pursuit of higher energy spending does not make us richer or wiser, says Smil. Nor does high energy consumption improve security, happiness, equality or build stronger democracies, adds Smil. In fact, Smil advocates a return to energy consumption levels prevalent during the 1960s. That means using one-third less energy than currently consumed by the average North American household. "We must break with the current expectation of unrestrained energy use in affluent societies," says Smil. In Smil’s Energy in Nature and Society, the scientist highlighted some uncomfortable truths associated with high energy spending. High energy spending makes civilizations fragile. "Expansion of empires may be seen as perfect examples of the striving for maximized power flows, but societies commanding prodigious energy flows, be it late imperial Rome or the early 21st century United States — are limited by their very reach and complexity. They depend on energy and material imports, are vulnerable to internal malaise, and display social drift and the loss of direction that is incompatible with the resources at their command." High energy spending fosters insecurity. "The Soviet Union nearly doubled post Second World War per capita energy use but with a crippling share channeled into armaments. Enormous energy use could not prevent economic prostration, a fundamental reappraisal of the Soviet strategic posture and Mikhail Gorbachev’s initiation of long overdue changes." High energy spending weakens economic prosperity in agriculture. "Increased energy subsidies may be used with very poor efficiency in irrigation and fertilization, may support unhealthy diets leading to obesity, or may be responsible for severe environmental degradation incompatible with permanent farming (high soil erosion, irrigation-induced salinization, pesticide residues)." High energy spending encourages materialism but not cultural greatness. "It is enough to juxtapose the Greek urban civilization of 450 BCE with today’s Athens or Florence of the late 15th century with Los Angeles of the early 21st century. In both comparisons, there is a difference of one order of magnitude in per capita use of primary energy and an immeasurably large inverse disparity in terms of respective cultural legacies." High energy spending does not bring happiness. "Just the reverse is true: it tends to be accompanied by greater social disintegration, demoralization, and malaise. None of the social dysfunction — the abuse of children and women, violent crime, widespread alcohol and drug use — has ebbed in affluent societies, and many of them have only grown worse." High energy spending diminishes human diversity. "In natural ecosystems the link between useful energy throughputs and species diversity is clear. But it would be misleading to interpret an overwhelming choice of consumer goods and the expanding availability of services as signs of admirable diversity in modern high energy societies. Rather, with rampant (and often crass) materialism, increasing numbers of functionally illiterate and innumerate people and mass media that promote the lowest common denominator of taste, human intellectual diversity may be at an historically unrivalled low point." High energy spending does not lead to greater energy savings or efficiencies. "Efficiency gains in engines or electrical gadgets have not been invested wisely but applied to the overproduction of short-lived disposable junk and into dubious pleasures and thrills promoted by mindless advertising." High energy spending does not improve quality of life. "Higher energy flows actually erode quality of life first for populations that are immediately affected by extraction or conversion of energies, eventually for everyone through worrisome global environmental changes." From: Energy in Nature and Society by Vaclav Smil (MIT Press). Award-winning journalist Andrew Nikiforuk has been writing about the energy industry for two decades and is a contributing editor to The Tyee. Find his previous Tyee articles here. This series was produced by Tyee Solutions Society in collaboration with Tides Canada Initiatives Society (TCI). Funding was provided by Fossil Fuel Development Mitigation Fund of Tides Canada Foundation. All funders sign releases guaranteeing TSS full editorial autonomy. TSS funders and TCI neither influence nor endorse the particular content of TSS’ reporting.

That's what I said: I think you're better off simply using weather compensation for UFH and not trying to mess with flow rates at the UFH manifold as that just adds another unecessary variable and will impact Delta P across the system, so just get rid of your actuators.

I often wonder about this and how this actually works. Of course we're seeing some of this all play out with Mandelson and his 'consulting' firm - all the senior ex politicians seem to be at it. However, I often think that a lot of these patterns are merely self-servicing rather than part of a larger 'vested interested' group. I also think that most politicians have nowadays been so sucked into the neoliberal way of thinking, that a lot of them aren't even aware of how this makes them think and act and encumbers them, and therefore they're not even aware of the real world effects in politics, economics and society. Awful as it may sound, I also wonder whether many of them have the critical acumen to really and properly question this and look at viable alternatives. As such, they just jump on the gravy train to get what they want and cash in on what can be quite an unpleasant and difficult public career in politics. I mean, if you look at the extremely narrow educational backdrop of pretty much all our leaders whether politics and business, it's really no wonder. And even if they do see what is going in, they're still so caught up in the ideology that they can't fathom a creative exit. Which I suppose goes back to my suggestion that it really is all down to how we think. Yup, all rather cynical, but every time in my life I've tried to go in a different direction with my stuff in business, I've found I hit a brick wall with the inherent status quo, and so I eventually end up back where I started merely navigating the existing playing field as best I can, learning how to jump through the hoops, whether I like it or not. Thank you!

This just comes from the fact that nobody, whether they like it or not knows what's achievable. And therefore trying to find consensus is just nonsense. But like I've said earlier in this thread - or was it one of the almost identical ones here that crop up on a fairly regular basis - the problem is not actually one of technology or engineering. Octopus, for example, have just got on and done what they've done and I'd argue that in doing so they've dragged the rest of their market with them. Similarly, I was listening to a conversation with a global solar entrepreneur talking about large scale solar installations in various regions and about how he was just getting on with it because the price was getting better as were the returns and social rewards. If you scratch beneath the surface of what is hindering progress, it's enough to make you shiver. One of these essential layers is that of government and the civil service. Both of which we know really don't work. One reason is because parliament is not actual sovereign, but the country is run by a small cabal that are the government. If you're not in the government you have little chance if any to have a say and influence the direction of policy. Another is that we really do have a lot of people in the machines of government who are totally incompetent. They typically come froma very narrow education path and don't have much, if any domain knowledge about the things they're supposed make decisions about and create pocily for. As really good book about this, worth a listen as an audiobook or a good read is Ian Dunt's book How Westminster Works..and Why I doesn't - here is a yourube video with him; On top of this, you then have what I consider to be poorly and narrowly educated leaders in the related businesses, including in the spere of the engineering and technology side. I was involved in leadership development and aligned education and it always struch me that much of what was learned and then being implemented was stuff straight out of academics' heads with little if any real world validation, and because of the problem of group think most leaders are taught exactly the same stuff and there is no variety. On top of this 10,15,20 years ago, leadership development had its eye on Silicon Valley as the bastion of exemplar leadership......enough said. And this doesn't even begin to touch the social aspects at large reagrding what you have rightly highlight as general ignorance about new technologies etc. The fundamental problem is how we think and it's going to take a while to shift that. The only way to shift that is through companies like Octopus pushing the market in a better direction and others doing the same. When I was building my house (well, I still am actually), I realised how much of my previous life and career was stuck in what I call concept and proposition. Lots of thinking, lots of writing reports and other documents and lots of giving guidance etc. but mostly it didn't achieve a whole lot. Now I'm doing heat pumps, which is my little contribution to making a change step by little step.

Ah, so this must be the truth then. Have a look at this. He explains the dysfunctional market very well, but if you want the TLDR, just go straight to 4:26. The whole video is worth a watch IMHO, plus he deals specifically with the economic ineptitude of the, "this bit only adds so much to costs" and how from a financial perspective this leads to excessive costs.

I was listening to Greg Jackson (CEO of Octopus for those who don't know the name) talking about the infrastructure upgrade decisions being made. He mentioned that due to these costs, we're highly unlikely to see any reduction is prices for the foreseeable on this basis alone.

Oh, it's great. I've got everything to basin/sink/toilet cystern on 10mm in my house, then just 15mm for everything else from a manifold. The 10mm completely negates the need for secondary return. When I offered to put in some 10mm for a customer having a new bathroom so they didn't have to use the excessive 22mm supply to the bathroom for their basin, the plumbers doing the bathroom install wouldn't have, telling them they had to have 22mm as it was coming from an unvented cylinder!

10mm, 15mm 20°C 60°C 80°C Easy-Lay PB - Horizontal 500mm 400mm 300mm - Vertical 800mm 600mm 500mm Has to be done if you're installing a gas boiler on PDHW. Still more than double the requirement of MLCP even at 20C flow temps and triple that at 60C Yeah, this is the general criticism you get from the super copper zealots of heat pump piping, and those making pretty videos on YouTube showing miles of lovely copper in the cavenous plant room, even regarding the Hep2o inserts. 😉 I always use the Hep2o inserts, even though I use Speedfit push-fit out of preference. I found out directly from a pipe manufacturer that as long as the pipe and fittings are to the correct standard, they're interchangeable. Hence I use Pipelife PB pipe as it has the same guarantee that Hep2o and Speedfit but it's half the price. I know some will say no-no to this but a lot of purchasing decisions are made thanks to clever marketing and companies wanting you to buy in to the entire eco-system, just like in tech. I just go by the principle of minimising fittings and using the natural capacity of the pipe to take bends - with MLCP it's a much easier task than both copper and PB/PEX. I have an MLCP ratchet hand bender which is compact and easy to use so makes this a really simple job - unlike with a copper pipe bender you can often use it in situe. So overall the pressure loss through the system is not a problem at all. The problem as I see it is more the lazy approach to plumbing you see so much nowadays. Recently I was asked by a customer why their cold water pressure was so rubbish and I opened up the cupboard in the utility where the rising main was only to find a silly circuit of 15mm pushfit with about 12 elbows and a handful of Tees to get the pipe going through a water softener. It's definitely requires a change of thinking about piping workflow, but I have to say I now wouldn't go back. Piping up a full system install with copper press-fit is just so much nicer, cleaner, less smelly, and quicker. The welding torch stays in the van unless it's an absolute emergency. Even with the odd cock up I've found resolving it is pretty quick and straight forwards - even when the system is wet and full of water. The trick is to do as much dry fitting as possible first and then go through the pressing. Well, I'm a relative newbie to the heating industry. I've only been in it about 5-6 years now. However, it's never sensible to develop your perspective based on one person. All I can say is that I have no doubts whatsoever about installing a new heatpump, unvented cylinder, pipe and radiator upgrades using MLCP safe in the knowledge that I won't get a callback due to a leak and that the system will perform as intended. But better to look at how much the stuff has been used in industrial settings and domestic settings throughout Europe for a very long time. I though it was interesting when I watched a technical heatpump video on heatpump system balancing and refining weather compensation curves that was filmed in Germany. Everything in the example plant room was in MLCP and not a single sign of a piece of copper.

In terms of redundancy, what exactly are you referring to? Is it to run extra loops in parallel - for example, if I need 300mm spacings, I add additional loops so that I essentially have 150mm spacings - or is it something else? I'd like to know more Gus as I'm keen to understand your perspective and reasoning for this. What are the thermal characteristics that are better and how is the system output controlled once it's in? I'm from the school of calculating heat load requirements in the room and designing emitters to satisfy this at a low temperature as possible and avoiding external controls as much as possible although I recognise and use room influence where needed. This approach does use the method of designing both radiators and ufh to the demand of each space. I'd like to understand more from your experience.

Obviously your flow rates & dt need looking, but also be very patient. I commissioned a new installation at the beginning of December that has very thick stone walls and had no heating for 3 months. Initially I thought I'd messed up the installation, but it's taken until the last week or so to find its balance. This is todays: This is what it looked like just after installation:

Yep, I have 100s of meters of the stuff in my store and it's very good. If I'm doing large installation work, MLCP and the fittings are what I pick up in preference of both push-fit plastic and copper. However, if I'm having to run new CH pipework through existing floors and joists, plastic layflat push-fit pipe is my choice as it's easier to work in these kinds of situations than MLCP. But in other situations it's not as good because it expands much more at high temperatures and the clipping distances are silly short - like 300mm on the horizontal - and it doesn't self support, so it sags. With MLCP clipping distances are over 1m and it has inherent stiffness and memory so when you bend it, it stays bent. Plastic doesn't stay bent but has a very annoying memory (even the layflat PB type) The big disadvantage with MLCP is that you typically need an expensive press-fit tool along with expensive jaws for each size of pipe you use. But you can now get manual press tools that are a lot cheaper and some manufacturers now have compression fittings available - I've even seen a German manufacturer with a push-fit fitting for MLCP but no sign of it over here. With MLCP you can also get pre-insulated pipes which save time and effort where you need insulated runs for the installation. Your other advantage with both plastic and mlcp is that you can run continuous lengths and minimise joints throughout the installation. Copper is very expensive now, requires lots of joints, and if you have runs in existing floors, it's just a pain. Even if it is pretty when first installed and polished, this tarnishes over time. Overall, with the brands I use, MLCP actually comes in at better value than plastic, believe it or not, and it has slightly reduced installation time overall even in retrofit jobs. What's also nice about MLCP is that you can dry fit all your joints without fixing them and then when you're ready go through it all with the press tool. Another small thing, that can sometimes be really important is that the sealing of MLCP is on the inside of the pipe. On plastic, it's on the outside, so you have to be careful you haven't damaged the surface of the pipe. With MLCP this isn't a problem. Since I've used MLCP I haven't had a single leak on an installation. That's more than I can say for copper and solder! And there's no hot works or stinky soldering!!!

Here is the technical sheet for Stelrad cast iron. There 4 column are about 100W mark per section at 760 high. 28968_Stelrad-HS_Cast-Iron-Column_Web-PDF.pdf

I gave that figure, which was chosen randomly, to provide an example of the difference in output of floor coverings for the same given MWT. This was to illustrate why you need to know what floor coverings you need. It was not in any way a suggestion of what you need. Yes, this is a good thing, but look at your chart. If indeed your output needs to be 17.8W/m2, the chart you use shows output with a screed floor with a covering of R0.1, this is the equivalent of 1 TOG carpet tiles or hardwoord flooring - so if you have tiles it will give more heat. You may have a problem here, because you can't run the heating system with a return temperature less than the room, so you're probably looking to reduce the heat output of these floors. Remember, your heat loss is calculated at an outdoor temperature of -3 to -4.6 in Somerset.

It depends on the control system, some of which are pretty advanced where you can specify which heat pump delivers what proportion of heating and how they share DHW demand. With Nibe systems you can even integrate ASHP with GSHP.

Ah, okay, I'll keep that in mind. Thanks. 🤣 What is the world coming to. I wonder if BH can cope...

No it doesn't skip over those bits of information, it provides you with the foundations for your design. Without it, you can't do any of the rest. The length of your pipework is actually irrelevant right now, that is just selected on the basis of pressure drop, not heat output. The heat output is given by the formula I provided. But in your design, you also need to know things like down losses, which is more involved than just knowing the thickness of your floor insulation because it depends on the proportion of external edges to floor area and the shape of the room. But it's not just down losses to the outside, it's also downloss in intermediate flooring because otherwise you can provide excess heat to the room downstair. And it's not just your floor downloss but the heat load of the room, which means you need your heat loss calculations. These will give you a required W/m2. Then you take the formula I gave you and you can calculated the average floor temperature and work back from there to determine mean water temperature and pipe spacing. What I gave you was a suggestion of book that provides you with a very easy way to determine what you need with simple nomographs - all you need to know is your pipe spacing, which you have on GF and the heat load in W/m2 and then you can find your mean water temperature for that system - it includes a standard screed and a spreaderplate. Or you can do it the other way round by selecting your mean water temperature and knowing your W/m2 requirement, you can find the pipe spacing. All you need to do is spent 25-30 pounds on the book and use a ruler. However, this just gives you a basic guide. You need to know your floor coverings why? Take a screed floor fairly standard covered with ceramic tiles a mean water temperature of 30C and target room temperature of 20C. With 150mm spacings the output of that floor will be about 55.5W/m2 and average floor surface temperature will be about 25.3C. If you instead had hardwood flooring you're looking at an output of 33 W/m2 and an average floor surface temp of 23.3C. As mentioned above, in some instances a resistant floor cover may give rise to greate down losses in intermediate floors. I work in the business and even though I have the industry guides to do the design so I can pull out the figures above, I still wouldn't sit down a do it myself because the UFH suppliers do the design for me and they have the software packages to do it. This is why you're not getting or finding a spreadsheet.

No, I haven't used the Ivar sets. It's good to know about these as a fallback - I'll investigate more! The weather compensation deals with it. The 'mixed' circuit just has different flow temperature parameters by setting min and maximum temperature in the controller and then this is adjusted as the whole house weather compensation does its magic. This has the advantage that the whole system remains open. But you can also set these things up to work based upon a set flow temperature with circuit always open, or with a room stat, or even have the circuit activated/deactivated based on the weather compensation curve or water temperature sensor.

TBH, on mine, if I lean forwards and go over a bump when my main boom is fully retracted, I almost get head butted by mine. I've been meaning to get new pins & bushes but like you say @ProDave it stll works fine, just with a good few clunks sometimes.

Normally what you would do is design the heating system to do this naturally. Each room would have its ufh output designed for the specific heat load - this means you might have different pipe spacing etc. The problem with a manual mixing valve is that it only works reliably with fixed flow temperatures, and many of them only really work well with high flow temperatures. They don't work well when you have modulation from the heat source that you will get with weather compensation. Using an electronic mixer is not the same as zoning, because you are not cutting flow to the zone, think of it as a heat area instead. What you're doing is controlling the constant flow of heat to that area, appropriate to its heating requirements. So, for example, on a cold day you might need a flow of 45C but on a mild day, it might be as little as 27C, depending on the house heating co-efficient (W/K). Therefore the house is still being treated as a single thermal envelope. The issue with target temperature is down to the floor buildup. If you have a buildup that has a higher TOG value, you need a higher flow temperature - and this may still be the case, even if your target room temperature is lower. None of us can answer this question because we know so little about the house design conditions. The reason we're suggesting a mixed circuit as a possibility is because you already have the existing one in place and we don't know anything about its design other than it's at 150mm spacings. We also don't know about the proposed design for the FF - is it going to be using speader plates, or is it screed too? There are so many variables you need to consider and then put together your FF design that complements the existing GF, then you'll be able to decide whether you actually need to have a mixed circuit or not. I think the whole mixer circuit thing was suggested as the alternative to hydraulic separation, not as a dictate about your design. So at the moment, if you're going to attempt the design yourself, spend your time learning about the design and then complete that process, including reverse engineering your existing UFH installation and go from there. Don't spend your time right now worrying about mixers. That will come later.

DM me if you want to. I've got 4 500mm ones taking up space - these are with 1" bsp elbows . If you want 750mm ones, then unvented components sell then uninsulated. Everyone seems to only sell them insulated now.

Both. Most of the new ones have pwm pumps. It's also useful to confirm minimum flow temperatures as some are 25C some are 20C, but in some cases this really doesn't matter.

Grant Aerona 290s are really straightforward for this, for example. You just order the installation pack with the mixer and then it's just a few wires in the wiring centre and then just wire in the temp sensor. You can also assign a room stat to that zone for room influence. The Grant, however, only has one weather compensation curve. As long as the open volume is sufficient, there should be no problems and no need for volumiser. My 6.5kW unit actually modulates down to 1.4kW

Just like I said, the heat pump controller is controlling the flow temperature of the 2nd zone with the mixer. It doesn't bypass the manifold, it regulates the mixing of flow and return water to provide the right heat input to the zone in question.

Not necessarily. If you're using spreader plates and then have carpet, the flow temp may actually be higher even with less heat load. It's all answered by the initial calculation and designs. The mixers aren't proportional or relay valves as such. They mix flow/return fluid to reduce the flow temperature of the system. So the strategy is not about controlling flow, it's about controlling system temperatures. Your system is then still one giant emitter.