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Correlation is not causation. Electricity prices are set by the highest priced, deliverable, energy, that is part of the half hour auctions. This is called the marginal price (I know you know all this). The high price is caused by this marginal pricing system. It would be much better if, for any given half hour period, that the mean auction price, based of weighted averages, was paid. That would get rid of those ridiculous price spikes, and reduce the potential losses at the lower end, I think. May try and model it later.

My point. At least with renewables we have the option of an alternative pricing structure to pass the benefit of the lower cost on to consumers (whether we do that is in thr lap of politicians and their lobbyists.... so I'm not holding my breath) But the point is that without renewables we will have no choice at all. Which makes the lobbyists job easier - so they put theor effort into slowing renewables. Far easier to prevent renewables from being built than to argue why a politician shouldn't take advantage of the cheaper power.

That's the point. The high price of electricity is being blamed, by some, on the increace in renewables capacity simply because renewables capacity is now higher than it was and prices are now higher than they were.

Hi Gus, To my mind this is not the issue, as I am comparing one cast iron radiator section against another. I called CIRC and as expected they can't give a specific reason why their section is upwards of 25% more efficient than all others, but they can say that no customer has raised this issue before. Is it just my experience or do the majority of building product suppliers in the UK seem clueless about their products. Anyway, as you also suggest I think if I use CIRC it is wise to oversize. My AI assistant summarises as such: Bottom line: With an ASHP, the risk profile is asymmetric. Undersized radiators force higher flow temperatures and reduce efficiency. Oversized radiators allow lower flow temperatures and improve efficiency. If you must err, err on the side of larger. Sizing to Paladin/Carron figures while buying from CIRC is a sensible, low-risk strategy. Worst case: you've got slightly more efficient heating and spent a bit more on radiators. Best case: you've sized correctly.

NO. It's the fact that the ridiculous energy market we are stuck with, prices ALL electricity at the cost of the most expensive which is gas. So even though from that graph gas provides less than 40% of our energy all of it is priced as if it were all from gas. We need a radical change to the energy market to stop this nonsense. Otherwise the promise of "electricity will only get cheaper with more renewables" will only happen when renewables reaches 100% and the last gas power station closes down. We are being conned / ripped off and most people are too blinkered to even notice this.

Statistics got to love them, but they can produce some rubbish information. You could add minor events like the Russian invasion of Ukraine. Sent gas prices through the roof. Building big nuclear generator, which the tax payer seems to be paying for and also adding to electric bills.

Is the increacing share of renewables to blame for the Uk's high electricity prices? Or is it that electricity prices track gas prices and gas has become more expensive?

I filled mine with water glycol mix and pressurised - they are not get crushed by anything. My pipes were installed as part of the foundations, so pre walls. Survived a Scottish winter.

I did similar with my super long DHW heating loop. Think it pulled an extra 15 to 20W

Thanks @Gus Potter, a useful reminder to follow the ‘KISS’ principle. I’ve been wondering about the strength of these pipes once they’re laid (before screed goes down) - some of the spacing is quite narrow, do we need to make sure that no-one steps on any of the pipe once it’s laid? (I’d have assumed that the practicalities of a building site would make this very unrealistic) I’m not doing the loop design myself (I’m drawing the line at buying a windows laptop just to use LoopCAD), and although the suppliers don’t share their designs before we commit to using them, we’ve had some say their design has 7 circuits and others say they have designed for 11 circuits. Are you advising that we make sure we ask for more than one circuit per room for the redundancy (just to make sure they factor it into their design)? Almost always ‘no’ 🤣 Thanks for the reality sense-check

Can you pop another pump is series to help the flow in that loop? The internal pump on our IVT9 is a bit marginal so I've an external Wilo to support it. Either will *just* satisfy the flow switch so with the externl pump ticking over it allows the Carel to modulate the internal pump nicely

Thanks Gus but the space is not all it seems. I have a space 245mm deep along the wall in front and 125mm on the wall to the right as there are kitchen panels, all openable, along the facing wall and cabinets, all of which will slide out for access, along the right hand wall.

Ok many will disagree with me but here is my take on it. I did my first UFH heating system when many here were in short pants. I'm now a designer. My appoarch is pragmatic and absolutely driven by what is achievable on site, buildablity and cost driven. I honestly despair when I see folk trying to desing pipe layouts room by room! I can go on at length but it is complete bonkers! Thoery is taking over reality. To start. You are going to install pipes in a screed say and that has to be made as simple as possible. You want someone that is going to do this right, that is experienced and they will need a labourer. Take the experienced person at £300 a day and a good labourer that is going to uncoil the pipes and and not be a bit hung over, (kink them) at say at "£120.00 a day. So the labour is £420 a day. Save a day and that extra can get you more pipes.. for 50 years! Now to save labour and reduce risk its easier to make all the pipes at the same centres. Design for the nearly worst case. In real life the concrete guy turns up and may squash a pipe. You won't know. So you want some more loops as a bit of redundancy. There is a thread about how folk cock stuff up.. take my advice and avoid this scenario. Of course I'm not going to be BH angel of the month but best to be honest and give it to you straight about how things often work out on site for self builders. Yes you may think that you will be up to site checking everything.. but that is often wishfull thinking! Even then ask do you really know what you are checking.. do you have the experience / constructionknowledge to know how to argue if you find something wrong? At the end of the install you want something that has some contingency built in. But if you consider the labour saving vs the extra length of pipe it is a good balance of risk when you consider that the pipes need to last 50 years. As an SE that is used to balancing real life cost vs risk, and done UFH long before BH was even invented, I must say that much stuff you see on BH about folk trying to save a few quid is frankly complete pish! But it's not my money! My advice is to install plenty and easily buildable spare capactity in the floor and once the pipes pop up you can play with your controls to your hearts content. It's a good apporach as boiler and design technology develops.. to have spare capacity in the floor slab.. even if you don't need it right now. Put in plenty loops as a guard against the builder catching you out or say in the heat of battle you are doing the screed concrete your self.. you can easily miss a trick here. Don't think for a minute that while it looks great on paper.. on site when the concrete is coming you will likely not have the experience to say to the concrete guys,, hang on.. the may bully you and play to your wallet. So to finish.. I say to many armchair techy folk that are trying to refine UFH pipe layouts.. stop having a laugh and lets look as what happens on site and the labour cost of fannying about with different pipe spacing. Many folk on BH end up moving walls or end up with a diferent kitchen desing layout. Self building is hard enough without getting over enthused about some hot water pipes in the floor.. keep it simple and that way you'll save on labour and reduce you risk of something going wrong. That's my view in the round.

Well spotted (I know a little and am learning a lot fast) - looking at GIRA app control, but not seen what the other hardware and equipment will be. Good point, it may be very little indeed. I’ve added this to the list of things to discuss with the designer. completely agree here, just trying to make sure in making one choice I don’t *unknowingly* create a problem or challenge elsewhere (it’s fine if I’m making a conscious choice aware of the implications) - part of the reason for asking this question is to glean any experience and knowledge from others who might do things differently or recommend things that worked out well etc. I like the sound of all of this, though not all applies in our design. Added to the list to discuss. Thanks @joth

That length of loop is bonkers! But if in the floor it is what it is. Question is.. is that loop near an external wall or not and if so.. by how much and is the cold wall on the upside of the loop or the cooler side? Next is does this matter? I know many are not keen on my rough and ready approach to UFH. But they will realise 5 - 10 years down the road when they are spending hand over fist to keep it working! or maybe want to sell! Now if you look at many posts on BH there is my view on a high reliance on software.. but pretty much none on BH know how that works! they blindly trust.. they certainly don't know that FE models are and often widely wrong. As an SE Fe is subject to lots of scrutiny as it often down right dangerous! The IStructE has many papers on this.. it's a great tool if treated with caution, a very handy aid! Ah but there is an upside. The first thing is to recognise that we have not lost the skill to be able to teach ourselves. When I went to uni at 40 was in tears on my first day.. I clocked that my educators were actually teaching me how to teach myself! You can only appreciate that when you go to higher education in later life. Yes we are a bit slower.. but also faster as we have the life experience to be able to identify what we need to learn in the context of the problems we face. Mike: Is the black line your actual room temperature? If so that does not reflect real life? What room was that in?

Not sure I knew you'd had those issues, Terry. That may be that you'd not shared back then, that I'd just not seen, or that my aging brain simply doesn't recall. I know I struggled physically at times with our build, so you did very well. We also downsized, or perhaps more accurately, right-sized. Though I never aimed for PH levels, our home performs incredibly well compared to our previous property. Over the first 7 years, our net energy cost averaged around -£100/pa. However, since last April, we no longer receive the RHI payments so this is the first year in which we're actually paying out for energy (albeit less than a third of what it cost us in the old house 10 years ago!) Like you, my wife's health forced early retirement (from teaching). In her case it was due to a whole bunch of complex medical issues, some of which date from birth, some that are much more recent, and (unfortunately) some that will likely have been caused by treatment she underwent in childhood. But the difference the house has made to her (and our) quality of life is absolutely priceless. I don't know how many more years we'll get, but I have no doubt it'll be more than we'd have enjoyed had we not built our bubble.

Was about making your house warm, rather than why it is not warm. https://www.bbc.co.uk/sounds/play/m002qrkc

Ah, that is a bit embarrassing. Fault lies at my end.. I should have explained in a better way. Blame is being a bit harsh on yourself. Ask and reflect. How much were you expected to know when you started? Evaluate how much you have learnt, take pride in that, and yes don't let it weigh on you. I'm making some posts that reflect my own experience. From a novice self buider to an SE / Designer that chips in here. I've made some horrible mistakes when running a contracting business! But at the time I did not know any better, I just did the best I could with the knowledge I had at the time. Now this thread is about.. hind sight and mental health to be blunt.. but also about trying to see how you get out of the woods at times when the world turns to shite. I'm chipping in as I am fortunate enough to see it from both sides.. as a past self builder myself and now on what you may call "the other side of the fence".

Already Done https://www.bbc.co.uk/programmes/b09fb6n5/episodes/player

Yes, it is. I should have split it. I have not found any controls for the pump in all the places I have looked but I am hopeful that I can squeeze that up a little further and witha complete pressure flush I can get the performance I want. Getting your head around how these things work and the perverse incentives (just the laws of physics really) they seem to have built in is fun. I have had that thought, the whole place is cold and it has a significant decrement / increment delay as you can see from the trends. I need to get the delta T down a bit more, I have 6 or so at the ends of those runs today which is re-assuring. I am hoping its just a sediment restriction in that long loop and I can get it cleared if not I am going to have to think a bit more out of the box aren't I. I was interested today to see how the heating affected the building and the slab. Going into the heating session this afternoon we had a room temperature of 16.5, at the end of the day before we had 16.9 so a drop of 0.4 deg C in 12 hours with a delta T inside to outside of 11 deg C. 6.549 kWh of electricity raised the temperature back to 16.9 deg C now. Over the three days 33kWh (£8.91) has lifted the internal temperature 5 degrees against an average delta of 10 degrees. Yes, rediscovering my inner child is real fun, I wish I still had the sponge brain I had then you can learn so much so fast its frightening now to think about how slow I am!

Thanks all, great advice.... To be continued.....(with another architect!)

I've had ME/CFS hovering around in my life since my first collapse in my early thirties. Luckily I spiralled out into reasonably good health over the next year and for the next 25 years, albeit with the odd post viral wobble. However, I then had a second collapse in my mid 50s and was bedridden for more than a year and had to retire early. Again 8 years of slow recovery getting to a point in my 60s where we could take on the self build. This really was a sweet spot for us: we had the time, energy and enough capital to take it on. But TBH the build was gruelling and by the time we finished, I was "running on empty" so another ME collapse, and another year+ pretty much bedridden. So doing the build extracted a toll on my health and as I stretch into my 70s I am still dogged by fatigue problems. However we've downsized from an old stone farmhouse full of character (but also high-maintenance / expensive to heat and maintain) to a cosy and cheap to maintain modern passive-class home. At the same time we freed up some capital to help our kids on the housing ladder. So yes, it was all worth it, but it did have a life cost. I couldn't do this again.

as an update, I have discovered that as we will be introducing an in roof solar panel array on south and west elevations, the possibility of a non ventilated cold roof isn't viable - https://roofingtimes.co.uk/ventilation-guidance-for-in-roof-solar-applications-glidevale-protect-can-help/ It seems my choice is now do is to select a variant of LR or HR underlay and then introduce the required ventilation strategy. It's very complicated!

I had a loom at this for my own house as wanted soemthing similar. True but what I cloked was this. @Anneker, I'm going to be a gent and say you are not as old as I. When I came back from Kenya to complete my secondary educuation Scotland was cold.. but the school really did have some real cast iron radiators. From memory the fins were about 150 mm thick and oval. The flow went in the top and out the bottom. The modern equivalent (replica) has the flow in the bottom and out also at the base. To make it work (modern column radiator) you need to fit a baffle at the inlet at the base.. which basically makes it almost work like a modern radiator. Now the baffles are not perfect hence the likely discrepancy you see. Architectural radiators need to make a compromise between performance and design look.. there is no free lunch. I would if I was you chose the thing you like, over size it a bit, say by 20%, fit a thermostatic valve. Make sure you have a good diameter flow and return pipe to it. In the round all this may cost you £100 quid more but I bet the paint on the walls is going to cost you more than that? Keep posting! Gus

Great advice I am unable to follow but wish I could. Burnt in large letters deep into the flesh of my core is the simple truth: “It’s all my fault”. Simples. That doesn’t mean it’s all doom and gloom, though it is on some days but not generally. But, if something wasn’t ordered on time, if two parts of the design don’t mesh like they should, if an operation is forgotten, etc. then I can look around all I like, I won’t find anyone else to blame. So I’ve accepted all the blame in advance and most days it doesn’t weigh on me. There’s a long list of other stuff that’s far higher priority for weighing on me, so it can go on the queue.