JSHarris

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JSHarris last won the day on March 10

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About JSHarris

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  • About Me
    Retired scientist, made the decision to build our own home a few years before retirement, then had the good fortune to be able to retire early and start the self-build journey. Started our build in late 2013, took far longer than anticipated to finish, but have now moved in and we are enjoying having a house with no bills at all (except for the blasted Council Tax...). The house pays us a modest income from the excess energy we generate, over and above the energy we use for heating, cooling, cooking, hot water etc, so we now have a healthy retirement holiday fund.
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    Wiltshire/Dorset Border

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  1. Welcome. As @ProDave says, there are quite a few hear that have designed and built passive, or low energy homes, using a variety of construction methods. Our house is timber frame (twin stud) built on a passive slab, with blown cellulose insulation in the walls and roof and airtightness that's a bit better than the PassivHaus limit.
  2. JSHarris

    SunAmp : Snog, Marry, Avoid?

    First off, I'm not an expert, by any stretch of the imagination. Secondly, @Barney12's problems are well documented here, as are those experienced by @Eileen, so there are at least three members here who've experienced some problems/issues with their Sunamps. I think that @readiescards may also have had a unit replaced by Sunamp. I think we may have around half a dozen or so members that have the newer model Sunamps, so it would seem that perhaps 50% of them, maybe more, have experienced some problems.
  3. I think repeatabilty is more important than the absolute value, as that probably gives a good indication of stability, so, with luck, the value will be consistent through the year. Although the blue book suggests 200Ω as the upper limit, I believe that one or two of the Part P approval bodies set a maximum acceptable limit of 100Ω, on the basis that this provides assurance that Ra won't increase above 200Ω through seasonal variation. I've still got an old 4 terminal tester, and although that's a tedious way to test an earth electrode, and I haven't used it in a long time. That does have the advantage that it's more likely to detect patchy ground conductivity issues, though.
  4. FWIW, to test Ra, a multitester will usually use the same function as used for testing Ze, and that pulses a fairly high current (around 20 A) from line to the earth electrode CPC in order to measure the resistance. IIRC mine uses a pulse of current of about 40ms duration for this test. Testing the trip current and time of the RCD is a separate test, only done once the electrode has tested out OK (Ra lower than 200Ω, ideally lower than about 100Ω). A 30 mA RCD only needs an Ra of around 2,333Ω to trip, whilst staying within the maximum safe voltage of 70 V on the CPC from the electrode, which is way too high a resistance to be acceptable for an earth electrode. For this reason alone it's extremely unwise to rely on an RCD test as a way to guess that the earth electrode is installed correctly and has a low enough Ra.
  5. As @ProDave says, without proper test gear, and the knowledge of how to use it, it's not something you can DIY. Apart from testing the installation, it must also be inspected to ensure that it physically complies with the regs, which means ensuring that the earth electrode is properly installed, that the CPC is of the correct gauge and properly terminated, that the terminal at the top of the electrode is protected by an appropriate housing, that the CPC is protected in conduit from that housing to the earth block, etc, etc. It's not a big job to do, the actual inspection and testing shouldn't take more than half an hour at most, if all has been installed as it should be.
  6. JSHarris

    SunAmp : Snog, Marry, Avoid?

    This is something that I feel guilty about, if I'm honest, as I know full well that my enthusiasm for the Sunamp PV, based entirely on my experience of its excellent performance, has influenced others. To now find that the new product has been engineered in such a way that it fails to perform as well as the original Sunamp PV, at least when used as a way of storing heat derived from PV generation, is disappointing. It may well be that there is a genuine fix for the various problems in the pipeline, but right now I'm afraid that I don't have a great deal of confidence that this is the case. The primary reason for my doubt has to do with the way that we're being drip-fed information, and have been getting a mixed messages, from denial that there are any problems, through to rather unconvincing explanations as to how the unit can be monitored to see if it's likely to fail to charge before it gets depleted to the point where we run out of hot water. I understand that the need for some form of feedback to the user is now understood, which is a step in the right direction. Right now I feel that there need to be a concerted effort to rebuild confidence in the performance of the product, and having a means to let the user know the state of charge, and whether the unit is accepting charge or not, is vital, IMHO, when it comes to convincing users that the product is working well. The suppliers of PV diverters learned this early on, and it's no accident that the best-selling unit has a pretty informative user interface.
  7. JSHarris

    SunAmp : Snog, Marry, Avoid?

    Right now I'd really like to talk with someone technical who actually understands their own product. All I've done is reverse engineer how I believe their controller works, based on observations of the way it behaves, yet it seems that I may know at least as much, possibly more, about the basics of the controller than the technical chap that's been tasked with talking me through things. It's frustrating as hell, as back when I first got the Sunamp PV I had several really sensible and useful conversations with a technical chap at Sunamp that really understood every detail of the way the control system worked.
  8. JSHarris

    SunAmp : Snog, Marry, Avoid?

    I've chucked the ball back in their court for now, as if they want to know how their new controller is performing then I need to be able to tell when it's on or off, without lifting the lid and sticking a meter on the contactor...
  9. JSHarris

    Freezer Not Freezing

    Sounds very much like a duff stat. Should be a relatively easy fix, with luck.
  10. JSHarris

    SunAmp : Snog, Marry, Avoid?

    I've been having some correspondence with Sunamp recently, as well as with other Sunamp customers who have had similar issues. The good news is that they are making changes to the controller firmware, that they believe will reduce or remove the failure to charge problem that we have for around 30% of the time. I believe that they have changed the charge acceptance threshold, but I don't know what they've changed it to, and TBH I doubt that it's a fixed value, given the challenges posed by trying to estimate state of charge from just three temperature sensors inside the heat battery (really a cell, IMHO, but they refer to it as a battery). Sunamp are certainly being helpful, and are sending me an updated controller, and have asked if I can assess it's performance. However, this is a Catch 22 request, as they've also said that I can't fit the status light to the new controller... The big problem this presents is that without the status light there is no way to tell whether or not the Sunamp is in the "accepting charge" state, which means that not only can I not compare it to the original controller's performance, but I have no way of knowing whether or not we are likely to run out of hot water the following day. I'm not that confident that they have really grasped the nature of charging a Sunamp from excess PV generation, either, as the suggested fix for having no indicator was to just time how long the Sunamp took to charge. Bit of a tall order when it's charging from variable power PV and you have no way of knowing when the thing is charged... My question about modifying the new controller to fit the absolutely essential status indicator has gone back to their technical people, but I have been given an interim reply that mentions it disrupting the way the controller senses the status of the heat battery, which is, frankly, BS, as the only sense mechanism is the chain of temperature sensors, and they are completely isolated from the heating element contactor (which is all that the indicator mod connects to). I'm really glad that Sunamp are looking at this issue, and have been working on a way to address it, but at the same time I've not got a lot of confidence that they actually know a lot about how either normal excess PV generation systems work, or how they interface with their product. This is completely at odds with the technical people involved in the Sunamp PV, who clearly had an in-depth understanding of what was needed to make best use of PV generation. I'm hopeful that things are looking up. though, and that I will be able to stop going into the services room every morning just to reset the Sunamp so we can be assured of getting hot water the following day.
  11. JSHarris

    Shower screen needed.

    I bought ours from eBay! It's exactly like the one in your photo, @TheMitchells, with the same style fixings. I can't find the seller right now, but it's an 8mm coated glass panel 900mm wide, and came with all the fixings. The coated glass is worth having in my opinion, as it "self-cleans", which means no more scrubbing the glass to keep it looking shiny. This is ours, installed:
  12. I bought our meter box from these people: https://www.meterboxesdirect.co.uk/ About £40 or so. The stainless steel IP65 wall box I've recently bought, which is going to house the new CU, only cost about £80.
  13. The only thing they might (rightfully) quibble about is having stuff other than their meter in the meter box. Strictly speaking you're only supposed to fit stuff like an earth block, Henley and perhaps a fused isolator inside the meter cabinet, so my small consumer unit and additional cables are a bit naughty. I'm in the process of tidying my cabinet up, by adding a stainless enclosure where the caravan hook up point is, removing the small garage CU that's in the meter box and fitting a new CU inside the stainless box to feed all the external stuff. Rather usefully, I was chatting about doing this to the chap that changed our meter for an E7 one, and he "accidentally" left some unused fuse seals behind...
  14. No, not at all. The only thing they were very insistent about was that I had to TT the installation, as it was a temporary building supply (the caravan box under the meter cabinet that has a Commando socket). As soon as we'd finished the build and wired the house I just moved the CPC from the earth electrode and connected it to the terminal on their head, so it's now TN-C-S. The house supply is a long run of 25mm² 3 core SWA, protected by the big switch fuse at the top. The fence has since been turned into a screen for our wheelie bins, with the meter cabinet still there on the other side (it looks a lot tidier now, with the ground level built up and landscaped):