Jeremy Harris

Good point, I checked the wrong variation of the base compound. There is a PRV on the top of the PCM cell, so the cell itself is protected from over-pressure.

It goes back a long way to when almost all house wiring was clipped direct to walls, often painted or even papered over. Gradually things changed to bury cables in walls, which then created another set of regs on how deep they needed to be to be protected (the argument being that if you can't see a cable then it's more likely to get drilled through). Safe zones were developed for buried cable runs so that we all know (!) where to expect to find cables buried in walls, too. The only other guidance on where you run cables on the surface is really to do with cable protection from mechanical and heat damage and there's no clearly defined rule as such (AFAIK, there may be something in the 18th I've not seen yet). It's largely a judgement call by the installer as to whether a cable is OK to run on a surface, bearing in mind things like cable max operating temperature, the possibility of something knocking into the cable, etc.

It boils at a mighty 880 deg C, so the plastic housing of the cell would have melted long before that, as would the cable, so I think the risk is pretty low. It's debatable whether the 2.8 kW heater could actually get the thing up to this temperature, as I suspect the heat losses would exceed the input power long before then The particular mix of sodium acetate and other compounds in the PCM will degrade if overheated, though, or so I've been told, so there is over heat protection built in. Immersions often (in my experience always) fail as a consequence of corrosion or scaling, and neither is really likely in the PCM cell.

No idea, but plastic trunking and conduit is either PVC or ABS, and PVC softens at about 80 deg C, ABS a bit over 100 deg C, and as far as the regs are concerned, the intention is to eliminate droop from softening under heat, I believe, for the reasons given for making the change for some locations in the 17th Amnd. 3, which was as @Onoff mentioned, a nest of tangled fallen cables impeding fire crews.

Bit of a bugger as I've recently wired the whole of my workshop with plastic conduit. It's legal as it's only along the walls and was done under the 17th, but would need to be in metal from next year on, it seems. Can't say that I have a problem with that; I'd have used metal if I still had conduit die and bending sets to thread the ends and bend conduit (lent them to someone who never gave it back, years ago)..

The IP for the report you commissioned rests with the author, not the person that paid for it, unless there was a specific grant of rights to you, other than to use the report in support of your application. if the neighbour really has copied a report from the local authority website and submitted it with their application, then that would almost certainly be a breach of copyright, but not related to you, as the person commissioning the report, but with the report's author. This means that the author of the report could choose to pursue the person who has used their work without licence, but not you. Morally I think you have a strong case for telling both the local authority and the author of your report that it has been misused, but whether either choose to do anything about it is doubtful; few people seem to think that copyright misuse is really theft, even though it is, in principle. I had a similar situation in reverse. My neighbour over the other side of the lane had paid around £4,000 for a flood risk report, covering the stretch of stream and the bottom of the valley where our plot is. I was asked to produce a flood risk assessment with my application, and initially argued that they had one from my neighbour, submitted just a few weeks before. The LA said they weren't allowed to use the contents of a separate planning application with regard to ours, and requested that I get another flood risk report. I asked the company that had undertaken our neighbours flood risk assessment if they could provide me with one. Yes, they could, for another £4,000. I declined, on the basis that they had already done all the work and would have been charging me to print off another copy of an existing report with a different client name on it, but respected their right in law to do this. My solution was to request data from the EA and do my own flood risk assessment, quoting only EA derived data. Not hard, took me a day or two, and it was accepted by the LA without a single question.

Fire- resistant support for some cables that can fall down has been in since the 17th 3rd Amnd, though, so nothing's changed there. The bit on a preview of the 18th I saw said this had now been extended to all locations, so all cable securing systems have to be fire resistant, so no more plastic cable clips, we go back to the thin metal strip clips we always used to use for cables clipped direct. I wonder if all plastic trunking and conduit is impacted by this? Seems probable to me, as I can't see the logic of banning all plastic cable clips but still allowing plastic trunking or conduit.

I only got the idea when seeing a team running an overhead fibre in the village a few weeks ago. It seems that in rural areas, where running underground ducts isn't really an option, they are just stringing fibre up on the poles, alongside the copper. The have pole-mounted combiner/splitters, I believe, so that a single fibre can feed several premises.

No, but I've put in a request for a quote for FTTP a couple of weeks ago. We're a few hundred metres from the fibre cabinet, but because of a quirk of the way the village was wired for 'phones, the copper goes around in a big loop before coming back to our pole so we have around 4 or 5 times the length of copper than would seem likely given our location. They've just added an extender box to our fibre cabinet, so I'm hoping that FTTP will be both possible and not too pricey. Main problem I found was getting an ISP to look into requesting FTTP from Openreach. Few seemed interested, and it seems that the request to Openreach has to come from an ISP they won't accept a direct instruction from an end user to run a fibre. I've surveyed the overhead route to the pole in the corner of our plot, where the under ground cable from inside our house runs at the moment. I reckon the fibre needs to be lifted on to 5 poles in total, all alongside a lane and all seem to have room to take a run of fibre, so my guess is less than a day's work.

Clipped direct is OK in a location that's protected, like that cupboard. Plastic cable clips are now out, though, and it will be mandatory to only use metal cable clips from next year, whatever the location (currently metal cable clips or non-flammable support is only required in areas where cables may fall down in the event of fire). Plastic trunking or conduit is possibly going to be impacted by the new regs in the 18th Ed I think, although I don't have a copy yet to check the exact wording with regard to cable support. As it calls for the use of metal cable clips everywhere, it seems probable that plastic trunking used as cable support may well be outlawed, too, but right now I'm not sure (anyone got a copy of the 18th who can shed some light on the exact wording, please?)

Initially, the heater slowly heats the solid PCM around the heating element until it changes phase to a liquid in the region around the heater. To prevent local overheating around the element, the heat is moderated initially by being turned on and off by the relay in the control box. As soon as enough PCM has melted around the element enough for there to be convection currents in the liquid phase, then the heater can run at full power, heating the liquid pool which then melts the remaining PCM in the cell. The temperature stays constant during this stage where the PCM is still changing phase. As soon as all the PCM has changed phase, then adding additional heat will raise the temperature of the PCM to store a little more heat, and then the heating element will be shut down. The PCM remains liquid until it's triggered to nucleate and start forming solid crystals. As these solid crystals of PCM form, they release heat, which can then be collected by the heat exchangers.

The only very, very slight issue is if the insulation used urea formaldehyde foam (which was used a few decades ago) then there is a slight risk from it degrading, dropping down the cavity and releasing toxic gases. Best bet would be to try and find the paperwork to ascertain what sort of insulation was used, or failing that, pay for a survey, which will involved drilling some small holes and using a borescope to check what's inside. Shouldn't be too much hassle.

Yes, there's a hot water version, but it needs water that's a bit hotter than the phase change material melting point (58 deg C for the DHW Sunamps) in order to work. Phase change storage isn't like hot water storage, in that the temperature of the phase change material (PCM) stays constant whilst it melts and absorbs heat energy as it changes phase. This means you can keep pumping heat into it at 58 deg C until all the PCM has melted, when it will stop absorbing any more heat without the temperature increasing. This constant temperature during phase change is what makes the Sunamp such a damned good hot water system, as it delivers water at around 58 deg C from fully charged to fully discharged, whereas a hot water storage system will tend to reduce the output temperature as it is used.

I think we're all open to trying new ideas; arguably self-builders tend to push the boundaries when it comes to trying new methods of construction and early adoption of new technology. Information from the web is inherently untrustworthy though, particularly when content is being commercially funded, or has been produced by someone with a vested interest in a product or system. That's one reason we work hard to keep this forum non-commercial, so that advice given can be as unbiased as possible and weighted to give more credence to those with real-world experience of a product or system. The key thing here is really how much practical, hands-on, experience that anyone advising any product or system actually has with using it. Videos can be helpful in terms of illustrating how to use a product, but will inevitably be produced and edited to highlight the view that the person making the video already has. There's no substitute for practical experience, which is why I'd trust an opinion formed by a decade or more real experience over any video on the web. If you have a lot of experience of using Uponor Q+E, and can let us know the advantages and disadvantages that you've found from a few years of your own practical, hands-on, experience in a range of installations, then it would be welcome.

O seal joints have a heck of a long lifetime, so they would be the least of my worries. There are tends of thousands of miles of MDPE water pipe buried around the country that all relies on O ring seals at the joints. There are 40+ year old black alkathene pipes with O ring fittings at my late Mother's farm, a fair few of them just in the open by water troughs etc, and I don't think there's ever been a seal failure - the only failures I can remember are when a pipe out in the open has failed and pushed the fitting off, and I think that's only ever happened once (may well have been that the fitting wasn't secured properly, too). Similarly, buried foul drain pipe has been using O ring push fit seals for decades, and I've never heard of them failing. Admittedly they aren't under pressure, but if O ring degradation was a problem they'd still start leaking sooner or later. According to the manufacturers, EPDM O rings have an unlimited life when used within their normal limits, which seems to support the view that the lifetime of O ring based fittings is likely to be greater than any of our lifetimes.

Exactly my experience. The first electrician I used not only did a poor job, but didn't register the Part P chit with building control. I chased him, then chased the body he was accredited with and they pretty much point blank refused to get involved, saying it was a matter between me and their member, nothing to do with them. If it hadn't been for another chap being prepared to inspect, test and sign off on this work then I could have had a problem. I'm convinced that the accreditation scheme companies really don't give a stuff as long as they get paid by their members. No one polices them, AFAIK.

No, it's fine. The problem is only with the plasticisers in PVC cable sheathing, and polyethylene, or any other plastic that doesn't use plasticisers to make it soft and pliable, will be fine.

Sounds like a good option for something like data acquisition and storage, which doesn't need much processing power or the plethora of ports that the full size RPi has. Can't say I have a use for one, though, as in many ways a RPi Zero W would do pretty much the same tasks, but in a cheaper, smaller, package, perhaps with lower power consumption. The latter is a significant issue if looking to battery power any of the RP SBCs, as none seem optimised for low power, and there are one or two applications where low power consumption is very useful.

I'm with @PeterW regarding the join(s). I spent ages trying to make a hovercraft duct that was round, using an external mould, thinking that this would both provide the right shape and act to restrain the board in a curve, but there were always bulges at the join. as soon as I switched to using an internal mould those problems went away, as a few ratchet straps around the outside made it easy to snug the whole thing really tightly down to the disc forms inside, which automatically pulled the join straight and tight.

The problem is that there are a lot of "qualified" people around who don't have a clue. I've ranted before about this with regard to an electrician who was registered as a competent person with one of the accreditation companies, but who was frankly bloody dangerous, and shouldn't have been allowed anywhere near an electrical installation. There's no way that most people are going to be able to spot whether work has been done to the standard required by regulations (which are often there to keep us safe), so the cowboys can carry on getting away with it. Programmes like Rogue Traders don't seem to have a problem finding cowboys, either, and some of the tales of woe on here seem to show that the problem is widespread. The shame of it is that we had a damned good apprenticeship system decades ago, and no one was able to call themselves a trades person unless they had served their time. There's no substitute for years of experience working under an apprentice master, IMHO, yet now virtually anyone can do a short course, get a bit of paper and pretend that they are fully competent to do a job properly and sign it off.

Yes, sorry, my fault I should have spelled it out. There's a useful list of common acronyms here:

I'm not trying to "make" you build anything, I'm only pointing out facts about the way heat transfers through structures, nothing more. If your priority is the thinnest walls you can get, yet still have both a good level of insulation and a reasonably long decrement delay to give comfort, then something like ICF or EWI on single skin block probably gives the thinnest overall build up. If wall thickness isn't as critical, then there are far more options, like building in block and brick and having a big cavity, around 200mm of so, filled carefully with whatever insulation you wish to use. Using a slimmer insulated timber frame with a brick or block skin works reasonably well, too. Who's suggesting you do that? I'd not build an all-timber house if I lived where you do, I'd probably opt for either ICF or EWI over single skin block, with a rendered external finish.

ICF, or block construction with EWI is one way to get a long decrement delay, but there are others, and concrete is far from being the only way to get a reasonably high decrement delay. Finding information on the decrement delay of different build options isn't easy at all, but the shortest decrement delay insulation that's commonly used is probably PIR/PUR. EPS and Icynene have between 1.5 and 2 times the decrement delay of PIR, dense rockwool, wood fibre and blown cellulose have between 2 and 3 times the decrement delay of PIR (all assuming the same overall thermal conductivity value). To a certain extent, insulation materials with a higher lambda tend to also have a longer decrement delay, as well as insulation materials with a higher heat capacity also having a higher decrement delay. It's the combination of the two that determines the overall figure, and, most importantly, it isn't just the insulation that is important in determining this, it's the entire build up of the structure, be it a wall or roof.

It's not about thermal conductivity on it's own, it's about decrement delay, which is the combination of thermal resistance and heat capacity of the structure. There's loads of stuff on the web explaining this, but in essence the higher the decrement delay of a structure the slower heat will travel through it for a given set of conditions. Time is the key here, and thermal conductivity (or it's inverse, thermal resistance) doesn't have a time component. We live in a climate where the outside surface temperature of buildings often varies over a wide range within a 24 hour period, yet we like our homes to not vary much in temperature at all. This means that the time it takes heat to travel through a structure has a significant influence on the temperature inside the building, and hence the comfort level. Building structures that have a long decrement delay provides a way of delaying the transmission of heat during times when one side is hotter than the other, which works both ways. It slows down the rate of heat transfer during times when the sun is shining on the outside, and also slows down the rate of heat transfer when the temperature outside suddenly drops, say a cold night after a warm day. The consequence of this is that the temperature inside remains more stable than it otherwise would. Key to this is that the periods when the outside surfaces of a building are too hot or too cold for comfort are relatively short; a few hours or so each day. If we can increase the decrement delay to a time longer than the typical time that the outside surface is too hot or too cold, then we can reduce the impact this has on internal temperature variations, which in turn makes the building more comfortable. There are other factors that contribute to this too, as the relatively high specific heat capacity of the plasterboard lining, plus the substantial heat capacity of the all the interior components, floor slab, etc, will absorb heat from the interior as it warms up, so slowing the rate of change of room air temperature and also release heat to the room air as that cools down.

I'll check ours and get back to you, as I don't have a record of having ever changed parameter 106 on my crib sheet.