SimonD

Yes, the Viessmann heat only boilers are a completely different beast compared to the system boilers - no opentherm/room compensation available. Even on the system versions of the 100-W return temperature is not available to Opentherm - or at least not some Opentherm controllers where you can interrogate what information is available for control. Whether it is available to Viessmann ones would be interesting to check.

Oh, nice, hopefully you can give me lots of feedback!

I don't want to hijack this thread, but here are some screen shots. The app will be open source with repo on GitHub of course. Problem is I keep on thinking about additional functionality and adding that after customer questions so I need to be more disciplined and release a version 1 I can then build on rather than continuously develop!

Better if you can send a dimensioned copy of the floor plans and elevations together with all the U-values for the elements - windows, doors, internal/external walls, floor, ceiling, roof, etc. - and the design air permeability or test results in q50 and any MVHR specs. Then privately share your postcode. If I have all these details I can run a fully BS EN12831 heat loss calc to current MCS standards which not only provides a heat generator loading, but also the room loading based on calculated air permeability. I can then also provide initial figures for any underfloor heating design and requirements together with flow temps & floor surface temps assuming that's what you're having. I have a tool that will soon be available free for self-builders, but I'm currently working through final bug fixing and hosting, so it's going to take a few weeks until it's online. Please feel welcome to send me a PM.

That's how the Huepar works for self-levelling. As @Nickfromwales says they're very sensitive to any vibrations and can wobble around like anything.

Yes, Huepar are great as is their warranty support. I had a lazer go on one of my units, they asked for a video, and then immediately shipped out a replacement for me. I've now had three! But I will warn you that although they're robust, don't kick them off the top of a roof so they bounce all the way down the ladder - they're not designed for that I found out, but the unit still worked for a couple of years without the protective screen over a lazer!

This will not in any way affect the local moisture conditions at the insulation/render/outside. It takes weeks if not months for moisture to pass through to the inside and with vapour pressure difference between outside driving vapour to the outside it's going to move in that direction.

You see quite a lot of freeze/thaw in the UK in winter - we even get it inland in England, especially with a well insulated house. There are a lot of places along the whole of the west coast of the UK that can suffer from wind driven rain without the opportunity to dry out. With the Finnish issue it was not the internal/external conditions but specifically to do the damp air/rain wets the thin coat render, freezes overnight and then thaws again in the morning. This required a revision of thin coat render standards and testing for the Finnish market in addition to the standard European tests. The thermal shock requires different polymers to be added to the render.

I think you need to take a more nuanced perspective on this as the picture is not as wonderful as this makes out. There are plenty of reports of problems with moisture ingress and failure of these rendered board in certain climates across Europe. For example: - All along the west coast of Norway, thin coat renders (directly in insulation) were suffering from premature failure as a direct result of wind-driven rain. As a consequence Norwegian building standards now have a map of areas where it is deemed unsuitable. - In Finland it was found that thin coat renders directly on insulation suffered from freeze/thaw failures as in that climate it is common to have lots of rain followed by freezing temperatures at night. This failure is in part due to how the render experiences a thermal shock due to local thermal conditions with the insulation directly behind it. This is one of the reasons also why many lime renders will simply not be suitable for woodfibre in particular and you must choose a render with specific ingredients to deal with the behaviour of the background material. I have woodfibre directly rendered, which sits on both masonry and timber frame, but being where we are, it's not exposed at all. If I were somewhere that freeze/thaw cycles were prevalent, like Scotland, and there was particular risk of wind driven rain, I'd be using a cavity and render board, no question. And also, although the woodfibre is often treated with a parafin like substance to provide better moisture resilience, it is not only vapour open, but it is hygroscopic and therefore any designs must take that into careful account.

That's probably what I would go for too.

Ah okay, yes there was a quiet update on the coil sizes. I think they still list the coil area as 2.7m2 but when you get the new ones, it's at least 3m2. Special order only, but that works fine for me on my jobs.

Yes, I wouldn't have the pir on the outside either. Principles are definitely to have insulation to reduce thermal bridging. In Sweden, for example, it's very common to have a continuous layer each side of the stud walls. You can then use smaller dimensioned stud. I wonder what the cost implications are of this compared to the cost of the 220 studs plus continuous layer?

I like the Grant cylinders, nice to install. They're also very competitive compared to the various others. I'm now gravitating towards these as a standard option.

I think the powers that be were listening to this thread. Just posted on efixx youtube channel:

Plus 1 to the Click Definity range - lots of options. We have the Metal white variant which is coated metal and looks better than plastic but not the stand out that brushed stainless for example. Brushed metal gets a bit messy when you have boys growing up in the house and sticky fingers are applied allover them. The Varilight we bought initially were pretty awful - cheap plastic screwless cover. And their V-com dimmers never programme correctly on LED strip lighting, even though they were recommended by the led lighting manufacturer!

Yep, https://professional-electrician.com/technical/guidance-on-installing-equipment-within-meter-enclosures-niceic/ Whether, as @ProDave says, anyone pays any attention or the CPS takes any action whatsoever is another matter. As a mate of mine once said. If you're not a member of a scheme and you do something stupid, they come down on you like a ton of bricks. If you're a member of a scheme and do something stupid, they wag their finger and kindly ask you not to do it again.

A good few years ago Microsoft was running an underwater study for exactly this reason - don't know where it got to but with the size of some of these centres, it would be a bit of a task to make them water proof. I think the tests they ran used units the size of shipping container. However, the massive scaling approach by AI is just one silly choice - it's the whose is bigger the better thing. It is actually possible to run very fast and efficient AI on extremely small installations, which maybe at some point they'll realise it makes more sense and costs less money.

Here is a bit of any answer for you which mentions single insulated with a separate flexible sheath: https://engx.theiet.org/f/wiring-and-regulations/29131/types-of-cables-acceptable-in-flexible-conduit

In all honestly I'm reluctant to make a definitive statement on that as it's really not my area. I call the electrician I work with! All I know is that you really need cables that are insulated and sheathed then made off correctly into stuffing glands either into a CU or junction box etc. or appliance and that's it's really good practice to run visible and exposed cable, even if it's insulated and sheathed, in trunking (unless it's something like HO7 or armoured and then it can take care of itself, but these also need to be properly made off into wherever they're coming from or going to). And also that you always use grommets into back boxes etc.

You should have seen what I came across recently when installing a heat pump. My electrician (who was the first electrician my customer had ever known to actually check in the meter box even though they'd had a lot of building work and re-wiring done) found that the armoured cable installed during previous extension work going from the meter box through loft and into the CU was undersized for 100A supply. Then he found that the armoured cable hadn't been made off correctly and the tails were single insulated, squeezed against the metal gland. The sparky who had installed it had then taken some spare insulation slit down one side and wrapped it around the single insulated tails to make it look like they were double insulated. Stunningly bad and the customer said the previous electrician apparently had a good local reputation......

I don't think I'd be sticking a wet finger anywhere near that installation 🙄 The whole thing look bl**dy awful.

Some years ago I bought a replacement charger for my macbook air, thinking it was a proper one and after a few months both my boys started complaining that they were getting electric shocks from the aluminium casing. I didn't believe them until I was sat there and got this tingling electrical feeling in my fingers and arms. When I went back to Amazon the seller had been deleted and there was no comeback at the time. I am very very careful about buying anything electrical from that place and some other markeplaces!

If you've got breeze coming from your sockets, it's very likely they punctured the membrane while installing the electrics - it happens a lot because the contractors simply don't understand airtightness.

Yeah, but like with just about everything we see on here at BH, we have a magnifying glass on the poor experiences of self-builders which shows it's incredibly difficult to find good professionals in just about every area of domestic building in the UK. E.g. I paid 3 sets of professionals and all three made fundamental mistakes and it was a humble bricklayer who knew how to use a tape measure and square properly in the end. And then the glulam manufacturer sent out a surveyor to confirm measurements before commencing production. All good then. Yes, totally. I got laughed at when I was seen with my own home made water level fixed to a datum point on my steel frame with more than 25m long tubing, going round the house to check my levels on the rebuilt brick walls, wall plate and glulam ring beam. Why not use a lazer level they said and I showed them than it some critical areas there was no line of sight and a water level was more accurate because of it. In the end, I think I had a deviation on one corner to corner level of 3mm thanks to this. It was brilliant also for measuring trench depths and topographical measurements as you don't have the issues with sight of lazer in sunshine, even when you use a green lazer and sensor. I still have it coiled away for the landscaping to come.