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Just a post to say a big thanks to @PeterStarck for his assistance and hospitality today. Peter pm'd me ref my ongoing bathroom saga offering a couple of pan connector spares he had that might help me out. I picked them up today combining a visit to a nearby wildlife park with my youngest. Peter and his wife were kind enough to show my wife, daughter and I around his fantastic build. I knew what it was but had never been inside a Passivhaus. I know I'm probably preaching to the converted but it just felt warm, secure and draught free.....something I'm not used to! Impressive views too through the triple glazing (it's in a lovely location). Add to that the fantastic build quality and that Peter's done the bulk of the work himself and it's even more impressive. Just hoping my missus will take something from it and come round to an appreciation of why I'm always on about insulation, heat loss and trying to do things "right". Once again a very big thanks.

For our ground works contract, all I did was agree in writing the specification, which included my site and services drawings, a QS costings and quantities table, the structural engineers drawings and specifications and the topographic survey (to calculate volumes) and agree a written schedule of works, broken down into stages, with a payment for each completed stage. I also included a few clauses to cover things like responsibilities, site security, a requirement for the contractor to give me a copy of his insurance and highways approval etc, just so we knew exactly who was responsible for what. This went into some detail, as it included things like the provision of toilet and hand washing facilities, secure site storage (I had none), the limitations of our self-build insurance with regard to anything stolen from the site etc. We only had one change, and that was to the invert depth and gradient of a drain, suggested by the contractor and with no cost impact (confirmed in writing). All told it was quite time-consuming to draw up, and I think I probably went into too much detail, but it did give me a bit of peace of mind! The house contract was a lot simpler. It was a pretty standard form of contract, with much the same as above but with the drawings etc referenced, and only small copies included in the annex to the contract itself. If I get time, I could have a go at editing out the stuff that's commercial and personally sensitive and seeing if what's left looks reasonable for a boiler-plate template for the house foundations and build.

Yes @Triassic sadly it is true, I have one prepared for every element of my build. I intend to submit them as part of my tendering process when the time comes later this year. I can't take all the credit as I lifted the various stages / elements out of an article in one of the Building magazines I read. If the Admin team could suggest a suitable place for future reference, I could up load them for everyone's benefit if it was thought worthwhile. PW.

The problem is that, in this case, the quoted MTBF seems to defy the known characteristics of a pretty well-modelled component, that's my concern. Few suppliers of consumer-grade components like this will offer more than around 100,000 to 150,000 hours MTBF, and that's over a restricted temperature range and takes no account of the cumulative effects of having multiple components in a bit of equipment. MTBFs can be misleading, too, as it depends how they've been calculated. I have a suspicion that, in this case, the well-known failures of the Enecsys microinverters may possibly have coloured the way Enphase have chosen to market their product! Reliability is quoted in terms of a statistical probability of failure, usually cumulative, and is always given under a specified set of operating conditions (not a range of them). When you have components that have a non-linear reliability, or life, with a variation in one, or more, operating conditions, then you can quote an MTBF for the "best" operating conditions, yet be sure that it will be a fraction of that for the "worst" operating conditions. Service life will generally be quoted as a number of years, but that does not mean that components won't fail within that period of time. If you keep a bit of equipment at a constant cool temperature it's service life will pretty much always be extended, often dramatically. It's one reason that places like data centres often feel a bit chilly if you're walking around inside one, as they provide masses of cooling both to remove all the heat the things generate and to improve equipment reliability. PV inverters are basically just switched mode converters, that use commutation and filter capacitors under conditions that are pretty near identical to things like data centre power supplies, fixed telecoms power supplies, brushless motor power supplies etc, in terms of switching frequency, ripple current etc. They are also essentially a consumer-grade device, they have to be in order to be cost-effective in a competitive market. A consequence of this is that they use consumer-grade components, rather than high-reliability "aerospace" or "military" grade components. There are some "ultra long life" electrolytic capacitors around, some with a predicted life of > 20 years, but they are expensive, and that long life is at the expense of a reduced ripple current rating and a relatively high ESR (the equivalent series resistance of the capacitor) both parameters that are critical to performance in a switched mode inverter, converter, power supply, or whatever. The effect of heat and ripple current on the life of electrolytic capacitors is well-modelled, and so the operators of equipment that needs to be very reliable (something like mobile phone mast power supplies, or data centre power supplies) will have routine replacement as a part of the maintenance regime to maintain the required reliability. One of the biggest drivers in that part of their maintenance regime will be the capacitors in the supplies, as they are the single most failure-prone component in this type of system (I have the figures somewhere, but off the top of my head I seem to remember that capacitors are around 5 or 6 times more likely to fail than switching semiconductors). Emerson have written a paper that gives a reasonably clear explanation as to why it can be challenging to determine how long capacitors will last in switched mode supplies: http://www.repeater-builder.com/tech-info/pdfs/replacing-capacitors-from-emerson-corp.pdf which is worth a read. It deals with high-reliability components, rather than consumer-grade components found in domestic equipment, but the principles are pretty much the same. EDITED TO ADD: I've just pulled off the Enphase (USA) research papers they use to justify the expected life and read them right through. All I can say is that there is one hell of a lot of optimism in there! They are using capacitors with a service life of 10,000 hours at the rated temperature, then arguing that because they have many smaller capacitors in parallel the service life, and reliability, increases. I'm no expert on the statistics of failure, but I'm not convinced by the logic of their argument. Happy to be put right by one of our resident statisticians, though! The other point in the research from 2008 is that if the capacitors degrade and lose capacitance, as they will, the inverters will continue to work at a lower efficiency, but don't, technically, "fail". It seems they have achieved this by the method I suggested they may have used, they've over-rated the switching devices so they can cope with the reduced capacity and increased peak switching current. It seems similar to the warranty on the Nissan Leaf battery, which says that (I think, need to check) that the battery capacity is allowed to drop by 20% and the battery is still considered to be serviceable and not elegible for replacement under warranty. Finally, the capacitors they are using are exactly the same as the ones I'm using in my BLDC controllers, Nichicon low ESR ones, and the research papers were written to help obtain venture capital. For those interested, the two papers I can find on this are here: https://enphase.com/sites/default/files/EnphaseElectrolyticCapacitorLife.pdf and here: https://enphase.com/wp-uploads/enphase.com/2011/03/Electrolytic_Capacitor_Expert_Report.pdf Neither seems to have been peer reviewed as far as I can find out. The question of whether any supplier will be around in 25 years time is a very, very good one. How many hardware technology companies stay around in their original form for more than 10 years? It's one reason I steered clear of the mobile 'phone app controlled home automation stuff, as I suspect some of it has a life of less than 10 years, if only because the hardware and software on mobile phones is likely to change dramatically over that time and render older applications unworkable, much as has happened with PCs and tablets. I have a perfectly good scanner that became unusable because Microsoft chose to change the way device drivers work from with the shift from XP to Win 7; when my wife upgraded iOS on her iPad the data link hardware (that was only around 4 months old) stopped working. As a final point, I'm far from anti-microinverters, and if you're going for a microinverter system there is no doubt in my mind that the Enphase ones are the most reliable on the market, as borne out by their low failure rate over the past 8 years.

A bit late actually since I finished this a few weeks ago, but that's all the roof insulated and lined. Blog at the usual place http://www.willowburn.net/ Look for the entry "Insulating the roof"

Never mind all this talk of misuse of the term "architect" the bigger problem is misuse of the term "professional" !! I've been disappointed by "professionals" in numberous different areas and their is zero legislation protecting that word! And there in lies my main point (which I've made before on here)........ do not ever, ever, ever assume that because someone or a company is a member of a "professional" body that they will be any good. Most are more interested in their members and their membership fees! Frankly a good deal of them are up their own arse! I'll get get my coat.

Hi @Triassic this is something I hope to use in the coming months. I'm grateful to @JSHarris for his input above, as I will no doubt use what he has mentioned to support my spread sheet. Groundworks.pdf

Thanks Terry, that all makes perfect sense ( it's just the boffins maths that I didn't understand!). I am doing exactly the same really although I do have a heat pump (bargain of the week on Ebay) but my ethos was heat the slab overnight when the lecky was cheap knowing it will switch itself off when a set air temp was reached. Hopefully this will last all day, if not we will light the wood burner to sit round in the evening or manually kick the ASHP on to top up the UFH. I didn't apply any maths, perhaps just gut feeling and a hope it would work. In fairness everybody is telling me Devon is mild enough that very cold weather won't last very long at all hence the electric panel radiators upstairs instead of UFH as the outlay would not be worth it. Jeremys situation where microclimate meant more than weather modelling ( cooling being more important than heating) makes me think that I have to " suck it and see" . Whatever the outcome this new house will be sooooo much cheaper to run than the present uninsulated house than I can't wait to get out of.

Thanks Jack and JSHarris. Will keep that in mind.

Dhw specs of the 838 and 938 For running 2 showers, the 938 is far better imo. Very much similar results to having a 200ltr UVC as the stored water blends in to reinforce DHW delivery from the plate heat exchanger. Benefit with the 938 Is also when the house is occupied throughout the day and lots of small amounts of DHW are being drawn off, washing hands after loo / swilling the odd dish etc, as there is no delay in getting the hot water to the outlet other than the pipe run. Both good machines, but if you want as near to UVC performance as you can get without having a cylinder, it's the 938 all the way. For a combi the DHW delivery is quite remarkable, but remember it's cold mains dependant so a crap cold mains = crap DHW, ( REGARDLESS of the boilers capability to provide it ). .

You can look at the warranty in those terms, yes, but you can also view it as a measure of confidence in the product. If they fail fast, then they'll need to be replaced one way or the other. Even if the disgruntled home owner has to stump up the extra costs for installation, Enphase will still bear the replacement costs of the unit(s). It's not as though someone will just leave a dead panel up there for 20 years (will they?) Bear in mind that the software that comes with the units lets you look at the per-panel microinverter performance over its lifetime, so it isn't as though a dead microinverter can hide anywhere. Exactly what they use, apparently. A bit of reading, again on the understanding that these are the manufacturer's claims (TL;DR - since the capacitors are run at significantly lower temps than their rating, their lifetime is massively increased): https://enphase.com/sites/default/files/EnphaseElectrolyticCapacitorLife.pdf https://enphase.com/sites/default/files/Electrolytic_Capacitor_Expert_Report.pdf Take it with a grain of salt, but they apparently claim a MTBF of 330 years based on accelerated testing. I did a lot of research at the time and I couldn't find any credible evidence of significant failures of these products. I'll admit it's early days though - these things have only been on the market for 8 years or so, so it's only about now we might expect to start seeing significant numbers of failures..

No reason why the microinverters cannot be installed away from the modules. Just more DC cabling. They can then be put somewhere cold and with the option of fan assisted cooling. My experience of inverters that cut in at a lower voltage is that they lose out at the higher end. As inverters are generally undersized in the UK this may, or may not, cause a long term reliability issue.

Absolutely correct ..! Hence the reason to put anti bump cylinders in any Euro locks as if there is no trace of a break in = no insurance pay out ... some little scrotes even use the keys they find to lock the door afterwards ... I've requested our doors with no cylinders - I just need the length and will order them from the company I get all my replacement locks from. They offer a guaranteed key cutting service too so I can get multiple keys. Also have the option of getting either a master key or keyed alike cylinders.

Enphase offers a 25 year warranty on their microinverters, They've published various white papers on capacitor life, which I suppose you can take or leave given they have an interest in a particular story. I seem to recall reading somewhere that the design of the units is such that even if the capacitors fail, they still work (presumably at lower efficiency and with significantly more ripple). A cynic might conclude that the capacitors are expected to fail at some point, but the user won't notice the drop in efficiency, so they won't claim on the warranty. Very easy (for us!), but that's because our panels are mounted on frames on our flat roof so can be accessed easily from underneath. Not so easy for more typical roof mounted systems, for sure! It's been a long time since I discussed this with the installer, but I faintly recall that there's another slight advantage in lower light conditions. It's to do with the minimum light that allows string inverters to start operating versus microinverters. I don't recall whether shading is required too, but basically on a cloudy day, there may be periods where the light falling on the panels in a conventional system will not generate enough string voltage for the inverter to start operating. With microinverters, the light level required for operation is slightly lower. We have a fair bit of shading, so they made sense for us anyway.

They do glass as that's what I wanted first of all. They make Windows and doors as there main business so glass would be no problem. Having 3 kids we would have been cleaning it all the time so for our sanity we changed our minds. Don't think of hand it was much more expensive maybe a few hundred. Don't phone ballycastle joinery try ballykelly instead!!!!

I would add to Jeremy's point above. If you know one panel is subject to daily shading and the rest are not, then that one battery that it charges will consistently get less charge than the others, effectively limiting the capacity of the whole system.

I'm not at all sure there's any evidence to support the first two statements, I'm afraid. The limiting component in pretty much any inverter, of any size, is the life of the capacitors. They have a tough time, handling high ripple currents and are seriously degraded by heat. The capacitors in a microinverter mounted under a panel are going to run massively hotter than those in an inverter mounted in a cool location, so are, in my view, more likely to fail early. They have a limited life even when run cool; perhaps 8 to 12 years would be typical. Replacing a single inverter mounted away from the panels is relatively quick and easy, how easy will it be to replace under-panel mounted microinverters? The second point is only true if there is shading affecting the array, where microinverters offer a good solution to allowing the whole array to continue to deliver a good output even when some panels are shaded. If there's no shading then microinverters are not better (in fact may be slightly worse because of slightly increased fixed losses) then a single inverter in terms of efficiency. The last point is very valid, and is the only real reason for considering microinverters. Edited to add: Just realised that in your drawing there are more points of failure than in a single 48V charge system, so it would be less reliable. If any one MPPT DC-DC controller goes down then the whole battery array fails. If any one battery doesn't get charged, then during discharge the battery array will go out of balance and you may well reverse charge the flat battery if you run things down low enough.

Thats what we have on the two smaller outbuildings. Yes you are right; it relies on powerline technology to synchronise.

Hello @Mrs H, and welcome ? after much research and visits to past projects, we decided to use a semi-retired Chartered Architect who mainly focused on self builds (a few each year) He was fantastic. He got us through planning and building regs and is "on the other side of the phone if we need him again" but we got our drawings and have been well on our way since. As was previously mentioned, no two self builders are the same and Different things are important for different reasons, but we felt he offered not only good value but really worked with us to get plans we loved. We had a site visit with him ( I am shocked by those who do not visit the site) For our 1st meet we drew up our own plans and wish list and presented him "our vision" but we were flexible. He gave us some great advise and alternatives. Helped us decide what we hated so he knew which way to steer. The cost included as many tweaks as we needed, he said on the first visit something like "if it takes 50 redraws don't worry, it's your house, but if it really takes that many, something is really not right" Took us 3 redraws and that was only small tweaks, as he had also done his research into us- He asked us lots of questions to gain an insight into us as a family, like most self builders "sell on" isn't much of a factor, it's nice, and nobody wants to ruin that, but the house is for us. He asked was it a family home? Were we looking at adding to it in future or downsizing maybe. Which rooms do we currently use most and why. He took note of Little things that make a big difference to how easy a house is to live in....i often work nights so sunlight in the bedroom isn't a plus for me, We have kids- glass balustrade are magnets for fingerprints but storage is essential and so on. He had a very good grasp of the planners likes and dislikes and we were made clear on what types of design would sail through planning, what he could push for (and if it was worth it) and what was a definite don't even go there. i think it's also down to the client too, we were very open about finances and what was important. My sister in law is also "selfbuilding" (i would say having a bespoke house built, she has a PM and main contractor...) she is now on to her 3rd architect and none of them have discussed finance much more than top end budget and at least one set of those plans is just never going to be achieved considering the groundswork within the budget. With selfbuild I have found that budget changes so perhaps "what are you comfortable spending" is more appropriate, do you want to save time/money (both seldom possible) . Some people have no idea what certain elements cost, did I want bi-fold doors once I knew cost and quality difference? nope! Does she? Of course, because she doesn't believe it's that much more expensive, in the scheme of things....(let's forget the fact we stay in north east Scotland and it's too windy and cold to even have a window open! ) Wow sorry that's a tangent and probably all standard but it's the little things that mean a lot they say! We got a fair few copies of the drawings and that helped a lot and also digital copies to send on for quotes etc. Best thing I have read on here, and I don't recall who by unfortunately, was that self build does not mean building what you dream of but deciding where to compromise. Wishing you well - Triple07

I'm a little more 'rough and ready' . I use my Bahco Spanner with the jaws wide apart, and push one jaw into the open end of the pipe. A quick 1/2 turn left, and another to the right, and it gives a perfect chamfer to the internal bore so, as Jeremy rightly says, it doesn't damage the seals on the fittings or inserts. A bit of silicone lube is advised, and can make this a bit less precarious a job for the uninitiated .

Typically I use 2 of these, connected to one of these, then a fan such as this. Ive fitted this exact setup in all of my wetroom / large shower installs and with great results. Ive used the 'dreaded' flexible ducting many times, but admittedly not for any real distance ( as I mount the fan in the ceiling usually and vent straight out the roof via a lead state and roof terminal ), again without issue. The centrifugal ( inline ) fans are very quiet indeed, and I've had to stick bits of A4 to the fans to demonstrate they're actually on and working.

Ended up painting the spindles white as with an oak for we thought it was just too much oak so needed to break it up. The dog sits there and watches the front door ready to attack and lick visitors to death.

Do not use flexible duct, that's just pure and simply poor design. If a fan is designed for 4" duct and you want to use flexible you need to use 16", and its still not as efficient due to 'swirl' in the pipe. And, each 90degree bend is another 1/4 size as well, try and use 2 x 45s instead. As above, inline centrifigual or bifuctecated is the answer, but bifuctual is probably massive overkill for a domestic, even a large domestic. A good 4" centrifugal will work with well over 5m of 4" (solid) duct, but tbh, at that length a 6" is going to be way more efficient.

I'm with Dave on this. I bought a standard in-line axial fan kit, fitted it to around 3m of flexible duct in total, and it was useless. Swapped it out for a centrifugal fan (easy to tell the difference, the centrifugal ones are a much larger diameter in the middle) and it worked like a dream. Axial fans don't like working with any sort of restriction to flow, whereas centrifugal fans will run without blade stall at pretty high pressures. Central (as distinct from in wall, single room) MVHR units all use centrifugal fans for this reason, as they are usually moving air through a fair bit of ducting.

A "normal " fan is an "axial" fan (think of a fan blade on an axle) A Radial, or Centrifugal fan generates a lot more pressure and can cope with longer runs of ducting. Here's one: http://www.screwfix.com/p/manrose-in-line-centrifugal-shower-fan-kit-chrome-100mm/41379

I think there will always be room for negotiation, but will just add a note of caution. An acquaintance recently had a new house built, on land they already owned, going down the main contractor route. Although he and his wife have run their own businesses successfully for years, I don't think he knew much about building work. He trod the fairly common path of getting an architect to design the house and get planning permission, then went to tender for a main contractor to build the whole house. He had quotes in from a few builders and selected one. As there always are when building a house, a few minor things changed as they went along, but nothing that should have had a major impact on price, in my view (I've seen his plans). When they got to the end of the build, the bill from the contractor was £20k more than the quote, on an original build cost of around £120k, IIRC. The reason given was changes in spec from the client plus increased material costs, both of which are in dispute. Needless to say the client was not at all happy, and so is still battling with the contractor over this increase, but I don't think he'll win, as he did not have a firm price contract with the main contractor, he just accepted a quotation. Firm price contracts are fixed in price, fixed price contracts are not fixed in price - variation is allowed for some things, like exchange rates pushing material costs up. Quotes are very often treated as an estimated price, neither a firm or fixed price and a quotation should be a firm price but very rarely is in practice. This last point is where I think a lot of people come unstuck, they believe a quotation is the actual price they will pay at the end, and often it isn't. One thing we found was that very few builders have a properly drawn up and negotiated contract procedure. They give a quote, perhaps with their standard terms of business, and expect to be given the job on that basis, with them having the freedom to adjust the final price as they go along. This is fine as long as the client is kept informed every time something affects the final price, and a good main contractor should do this regularly, so the client knows each week or so what the changed final price will be. Some don't do this, as in the case of my acquaintance, and then the client gets a nasty surprise at the end. We didn't go down the main contractor route, but we did have two main contracts, one firm price contract with the ground works company (roughly £50k in our case) and another firm price contract with the house build company (who built the foundations and weather tight and insulated house frame and a detached garage) that was a bit over £60k. I drew up both contracts, and agreed them with the contractors, with agreed stage payment plans. From the discussions I had with several companies during the tender stage I don't think many usually worked to any form of written contract at all. So, my advice would be to choose a main contractor that has priced realistically for your area and try to agree a firm price contract, rather than accept a quotation. There is always a risk with a firm price contract that the price will be a bit higher, as the contractor will build in some risk contingency to his price, but for you the advantage it that you know what the final price will be. The other down side with a firm price contract is that it limits your options to change things as they go along - each change needs an agreed variation to the contract. Alternatively, agree a fixed price contract, or accept a quotation, and ensure that there is a clause requiring the main contractor to discuss price changes with you on a regular basis.

'That's 6 more than I have' sighs Faye... This is the baby itself http://www.pauldavieskitchensandappliances.co.uk/miele-3-powerflex-zone-induction-hob-km6366.html

Don't bloody start him off !!!!