dnb

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dnb last won the day on February 14

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About dnb

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  • About Me
    Building a SIPS panel house on the Isle of Wight, in the muddiest swamp I could find.
    Just call me Shrek!
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    Isle of Wight

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  1. They had away with a lot of my PD rights too. I had to do a load of bat boxes too - I enjoyed making those and I like seeing the bats flying at dusk.
  2. Good luck with the next stages. Hope you didn't get hit with too many conditions.
  3. They've indicated that there's quite a lot of PV already on "my" bit of wire, so I might not get the full 16A worth. (I won't know until I get the results of my application). They only seemed concerned with the export, not the total size. In reality, they aren't going to ever see any of it in the first place - it will be directed to local use of some kind for all but the most extreme circumstances. I too might be in this position. The house is specified to have full A/C - it's always good for soaking up a bit of spare power. Can always open a window to make it work harder...
  4. Exactly this. But they seem to be getting more common these days according to this: Single phase inverter, apparently with G100 export limit I applied for an "in principle" grid connection with SSEN recently using one of the above as my export limit, and they seemed happy. We'll see if that is still the case now the real application is ticking through the system. Admittedly I am only looking at 6kW or so of panel, but my export limit is likely to be in the region of 3kW.
  5. In the middle of a build now. It's been pretty horrible really, but not all of it is covid 19 related. You might have a bit more luck than me. PP - no idea since mine was all done beforehand, however building control are snowed under looking at photographs and currently won't attend site in enclosed spaces unless it's a final inspection. This will depend largely on your local authority. No idea on mortgages since C19 either. Some materials are nearly impossible to get. This is regional as far as I can tell, but could well be coloured by being on an island. Other things are easy. Trades do seem to be working fairly normally where materials are available for them. For instance, plaster is impossible here unless you're willing to pay 5x over the odds. Kitchen worktops are in short supply too, so I'm told. I was fairly fortunate here in that I had bought most of the materials I needed to get to sole plate level a couple of days before lockdown. The worst one for me is that my SIPS panel contractors can't be accomodated locally, can't easily subsist and can't commute. So the house can't meaningfully progress upwards until the B&B world opens up a bit more.
  6. I promised some mathematical modelling. Not the clothes kind. I'm much better at the former. Here are some charts and things. It turns out that modelling rainfall is almost as difficult as modelling sea clutter as seen by radar. I ended up with a uniform distribution for deciding if it would rain on a particular day, and then a gamma distribution to determine how much rain there would be. It sort of worked but plan B - getting real world daily rain data for my area for the past 89 years - seemed a considerably better option when it appeared! I wrote a quick and dirty Matlab script to read in the rainfall data, then in a loop (couldn't be bothered to vectorise) of 1000 runs select a year at random and run through each day to work out how much rain my roof and a 4000 litre tank could capture less a fraction for efficiency of capture, followed by "using" 150 litres of water that day (no idea if that's the right amount, but it seems sane for the moment). Anything that drained the tank counted as mains usage. This gave me the following charts, averaged over the 1000 runs: The rainwater tank ranges from zero to full for most days at some point over the 1000 runs, but there are more zeros in the spring than in winter - hence the higher average mains usage. Means are pretty useless statistics though when outliers are involved (i.e. full and empty tanks) so let's look at the median. This clearly says the expectation is that mains water will not be used (on average) and that 4000 litres is sufficient storage for using 150 litres per day (again on average). So let's look at the 95% "worst case" level, since average is wrong half the time... In this case, the system only provides 30% of the water we need. But 95% of the time, it will do a lot better. Let's now look at how much better by plotting the mains use percentile for each year. It shows that the system usually provides sufficient water to sustain near zero mains use provided the assumptions on water use of 150 litres per day are sound. All ready for you lot to throw rocks at the charts now 😀
  7. That looks too much like my day job at times.
  8. My blockwork skills have improved a lot over the bank holiday weekend. 90 blocks placed to 3mm accuracy in height. 😁 I was assisted by my daugher, the site foreman with "the stick of office" (sensor pole for the laser level thingy) and the real boss on mixer duty. (It's not too different to a Kenwood Chef ) Happy days. Until I started dreaming about blocks last night. A dreadful nightmare about how they were all laid perfectly in a staircase painted by MC Escher. The timber frame boss was very cross with me because it clearly wasn't flat enough. This was shortly followed by us both being cross with the man from English Heritage who appeared from nowhere and declared it a listed building because nobody had made a real Escher staircase before... Oh well, back to work for a rest.
  9. Nice data source. Working on some Matlab tonight so I can have a MonteCarlo rainfall model.
  10. Nice idea. I can reuse code (and some hardware) from my solar diverter project. Would be worth doing this in addition to my 1st plan because it will help to detect more fault conditions. I have a prototype microcontroller based tank level sensor I made for my father-in-law's yacht water tanks - it works on air pressure so has no moving parts in the tank itself (he thought it important for improving reliabiliy and repair time) , so was going to use this to switch off the pump and switch on the mains water when the rain water tank level got low. I have to admit I haven't got a good computer model of this yet, (It's what I do at work) but my best guess is that rain capture will be almost seasonal. There will be much too much in the winter, and then no rain for ages in the spring and early summer, followed by vague sanity in August, September and October where the rain is distributed more evenly. Neither am I. But I suspect that an overflow that can keep up with the pump and the fresh water together will be OK if it keeps a specified minimum separation (20mm comes to mind for no reason I can remember) of the mains outlet from the level in the tank. Good call. Baffles and chambers won't be useful here. I have thought about this and I'm still undecided if it is more efficient to do this or my first plan. It might prove easier though and that's worth a lot. The weather modelling will tell all here.
  11. Thanks. That will be very useful. I do. It is currently connected to a single outside tap near the old garage while we wait for the house. I will be doing similar this whatever the outcome of this investigation. I am currently of a mind to use a header tank to gravity feed water to all the toilets etc so that it's easy when the time comes to manage air gaps etc. so I can avoid potential expense with needing low volume production parts that require some kind of approval, and in theory can get away with a smaller (and hopefully more efficient) pump. We'll see if the maths supports this hypothesis. Space for the header tank isn't a concern. Thanks. Nice to have a good review! I am not obliged to do this by planning, but it helps with the water use part of building control. SWMBO wants a large bath and some kind of high volume pressure washer as a shower so the deductions from water reuse are extremely helpful. (Our BCO has indicated he's keen to see compliance with the water usage)
  12. I have rainwater reuse in my plans, but the build budget is tight (thanks to current events) so I need to keep things cost effective. I've noticed that there's a lot of expensive kits for using captured rain water and most of them look like I can make something almost identical for considerably less outlay. Let's say the budget is around £750 to £1000. (This is based on rounding up 33% of our expected water bill for 5 years, plus an allowance for things getting expensive) I plan to use the water for toilets, garden, car washing (with a decent filter!) and possibly for clothes washing (again if filtering can be cost effective). ICBs look like a good and cheap option for water storage, but I'm a little concerned about cost and complexity from burying them in clay and expecting them to stay connected, so I am considering an onion type septic tank as a rainwater tank. It seems considerably cheaper than a rainwater tank for the same (4500ish litre) volume and with very little work, e.g. to implement filtering and a calmed inlet, will do the same job. I assume the price difference is due to production volumes, because the calmed inlet and filter are often additions. My plan was to fit a header tank in the attic since this looks to be the simplest arrangement with the lowest running cost. Mains water can be directed into the header tank with a simple float valve maintaining sufficient air gap and I can implement a control system to turn off the mains supply with a motorised valve (probably a ball valve since it doesn't use power when in either state unlike a solenoid valve - and it can be manually moved when there is a power cut) when there is water in the main tank. This leaves the tank water side. A submersible pump, a pressure based controller and a float valve (probably one with a sharp cutoff) is again a simple and relatively inexpensive option. It does everything I need except sensible dry run prevention. (My theory is that dry run protection built in to the pump probably shouldn't be routinely relied upon.) So in addition I'll need to implement a tank level indicator of some kind and controller to switch the pump and the mains valve. (Sounds like another little microcontroller project, or something for a cheap "smart relay" device...) The tank and the pump use up most of the budget but I have a shed full of random spare parts that will more or less do the rest. What am I missing (apart from a lot of implementation detail with many a devil lurking inside)? Any regs preventing me from using a new septic tank for this purpose for instance? Can I do anything cheaper or more simply? I note there are lots of German and Polish parts on ebay that are very well priced compared to UK parts. Are we that far behind the curve when it comes to sensible water usage?
  13. I can't really help, but I had a similar situation with my road and electricity supply. We are on an unmade and unadopted road where the ownership details are lost to time. (We have an indemnity policy in case an owner ever appears and gets uppity). Of course this didn't help when I wanted to dig a trench across the road to put in a new site supply so I ended up with a pole in the front garden and an overhead cable over the road - it got around the problem nicely for me, but I guess it's not an option for you.
  14. That's easy - it's because I'm impatient with technology. 😉 The boot time is not the critical issue, but it is a factor in the design choice. Robust and quick recovery after a power cut is another design consideration - we get a lot of power cuts. (Enough that I am considering a small generator backup once the house is built, but that's for another thread.) Fundimentally I want as simple a solution as possible to the problem. My toaster (to quote a joke example from the early internet) does not need to run Linux! All will be revealed in a different thread. It's not a single project and is best presented when I have the whole system sketched out - I have a set of things I want to implement that would have improved functionality if they can communicate in a simple way. Complexity and extra processing power doesn't give additional benefit. They need to be supportable (by me) for 10+ years or until we stop wanting to pay "eco tax" (a thread in its own right) on energy and resource saving equipment in our houses.
  15. Ready built would be good, but I can usually convince someone at work to help out with bargain price PCBs. As long as it doesn't need anything other than the basics - a few PTH, silk screen and solder mask.