JSHarris

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JSHarris last won the day on December 11

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About JSHarris

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  1. I did spot rare bit of Welsh humour yesterday evening. I was driving behind a driving school car, and amongst the usually signwriting on the back asking for patience and warning that the car may brake suddenly, there was a bit that read "No learners are left in this vehicle overnight" Right beneath that was a Welsh dragon sticker, saying "Keep calm - I'm Welsh"................
  2. Probably best to go back to basics and assess the boundary parameters of the thing you are trying to measure. In this case, you're looking to measure changes in the temperature of atmospheric air masses at a particular height. Because of natural air movement, the scale of the terrain etc, these changes will only happen over large areas, certainly many tens of metres across, most probably hundreds of metres across. Additionally, you need to separate out still air temperature (the thing you are trying to measure) from the cooling effect of air motion on the sensor, plus the cooling effect of evaporation if the sensor gets wet. That means the sensor needs to be in a shielded location where it won't be affected by either the air flow around it or moisture. Decide how accurately, and how quickly, you need to measure the air temperature, then look at what is realistically achievable with any form of sensor. We used to measure outside air temperature using a sensor tucked inside the static tub of a pitot, inside the head but not directly affected by the air flowing around the head, because it was buffered via an air pocket. That generally worked well, but I can say with certainty that atmospheric air temperature changes are both small and gradual, over a wide area. We used a mix of different sensors, from fast reacting thermistors and diode junctions (both a complete pig to characterise and linearise if you want accuracy) to thermocouples and hot wire sensors. The latter can react very quickly but are more sensitive to accelerated convective heat loss, so are better for measuring air flow rate than they are for measuring temperature when placed in a shielded container. If you want to experiment, without having accuracy then you could try just using a thermistor probe, placing it in a well-shielded location, and masuring the variation of resistance. It won't be linear (if you want to get the temperature from one you have to compensate for both offset and the inherent non-linearity) but you can get very low heat capacity, fast response time, miniature glass bead thermistors (I probably have a few somewhere). My guess is that you will rediscover what others have found, that air temperature doesn't change quickly and that the variation in temperature across small air masses (those with dimensions in tens or hundreds of metres) is very small indeed. My experience of doing this with aeroplanes has been that by far the biggest factor is altitude, specifically the environmental adiabatic lapse rate, which varies with humidity, but is around 2 deg C per 1000ft in still air (more info here: https://en.wikipedia.org/wiki/Lapse_rate ). Finally, you can get the DS18B20 to read to 9 bit resolution in around 94ms, if that sort of resolution is good enough for what you are looking to do.
  3. A plain DS18B20 takes around 750ms to measure and output a 12 bit temperature, already calibrated in deg C. Easy to read and display the data, too. https://datasheets.maximintegrated.com/en/ds/DS18B20.pdf
  4. How far can you get in an hour

    Go up there for a holiday. Stay in one of the hotels in Portpatrick (the Fernhill is pretty good, avoid the Portpatrick Hotel up on the clifftop). Drive around the local area and see what you think, the area is great and it's the most friendly place we've ever stayed. The main issue around there is unemployment, when we left it was still running at around 20%, and we were the biggest local employer, so things got worse when we closed down. The only employment locally is the creamery and the ferry port, everyone else is just scraping a living from smallholdings and some bigger farms, plus some fishing.
  5. How far can you get in an hour

    I used to drive past that twice a day, driving to and from work at West Freugh, from Portpatrick. It was still a dairy farm back then. Lochans is a nice little village, inland and far enough away from Stranraer. There was a fair bit of housing development going on there just before we left, so my guess is that Lochans may well be bigger now than it was. There's no pub there, though, or wasn't when we left. Portpatrick has the advantage of half a dozen bars, including at least one really good music bar, with live traditional music at least one night a week.
  6. TBH, I thought your quip about the extra orifice was pretty funny, but then I had followed @Barney12's original link and seen that the strap on referred to was a pipe boss............
  7. It's easier to just block them all in your router. Takes a bit of effort to do initially, but not a lot of effort to update the list from time to time. I also have all the Microsoft related "telemetry" sites blocked. For a time it was good enough to just have a comprehensive hosts file on the local machine, but I fear that they have found a way around that method of blocking hidden traffic. The hosts file is still useful, though. The main benefit now is making the BBC News website work properly, so that the "breaking news" banner doesn't stop you mid-way through reading an article by automatically scrolling the page back to the top. If anyone finds this as annoying as I do, then just adding the line: 127.0.0.1 polling.bbc.co.uk to their hosts file will kill the breaking news banner, at least for the time being. The BBC News website is pretty insecure and very easy to modify, so this work around may well stop working when they update it, as I'm sure they will soon.
  8. Plumbing 101: the absolute basics

    Looking carefully at the manifold, it seems that the right-most loop is always on, as it has no actuator, but is fitted with a cap to hold the valve open, so it is acting as the bypass.
  9. Solar PV DNO Engineering Recommendation Code

    It should be set to G83, but TBH, it probably doesn't make a jot of difference with a 16 panel system, as I doubt the peak output exceeds the 16 A per phase limit of G83 anyway, even with the inverter set to G59. There's no practical difference between G83 and G59 in terms of how the inverter operates, or the safety provisions, and the chances are that the inverter may well be limiting the output to less than 16 A anyway, based on its rating. I'd not worry about it, if it were me.
  10. The value of an apology

    That's if the design teams have any liability or guilt. My feeling, from having looked closely at the original design drawings and specifications for the renovation of Grenfell Tower is that the original designers may well be those with the lowest, or even no, degree of culpability. My personal view is that 99% of the blame lays with the cost-cutting that led to the materials being changed AFTER the design stage, by some of the other people and companies involved. Top of the list has to be the project manager at KCTMO, as she was responsible for managing the prime contractor and ensuring that the prime contractor, the sub-contractors and building control were delivering a safe and compliant outcome, at the agreed price. I think we will find that cost-cutting after the design stage will be partially to blame, with the substitution of materials that were not as specified by the design team, and that both poor overall build quality and building inspection standards will also be partially to blame for allowing the design changes during construction that allowed there to be fire entry points around the openings without adequate fire stops. The original design seems to have had horizontal fire stops specified that may well have been good enough to have limited the spread of this fire, even after the construction company changed the material specifications (with the sign off of the KCTMO Project Manager, I am sure - I doubt that they could have done this unilaterally), but for whatever reason it seems that these were not included in the final construction.
  11. How far can you get in an hour

    It's further from civilisation than it looks, though, as if you want to do any serious shopping (DIY stuff etc) then you're faced with a 60 mile each way drive, either up to Ayr and back or across to Dumfries and back. We found it was easier to get the Seacat across to Belfast - 20 mins and your's right in the centre of Belfast practically. No good for heavy stuff, as you can't take the car, but as a shopping centre Belfast is pretty good. The main snag is that none of the roads are great. It's nearly two hours to get to the border at Gretna, for example, or about an hour and half to get to Glasgow airport. Stranraer is also a bit of an iffy place, very rough at night. Out on the Rhins peninsula at Portpatrick it's like a different plant though, and a very nice place to live indeed. House prices are low up there - when we moved from there to West Sussex we ended up paying nearly double for a smaller house, and went from a 30% mortgage to a 95% mortgage, not nice. Luckily I had relocation assistance that covered the first five years of the mortgage cost difference, and by then inflation had increased the value of the house we bought, so the LTV on the mortgage came down a great deal.
  12. The value of an apology

    One problem is that, although the law states that an apology may not amount to admission of guilt, juries ALWAYS think otherwise, and there will be court hearings where juries have to decide on the guilt or innocence of several different parties relating to contributory factors to this fire, I'm sure. The design team specified an approved system, that complied with the letter of the regulations. That design was then substantially modified downstream by contractors who were either specifically asked to do so, or were under cost pressures to do so in order to win the work. However, from all I've read so far, the materials themselves met the required approvals on their own, with the possible exception of whether some were actually certified for use on such a tall building. The real grey area is that the building regulations themselves were undoubtedly breached, that seems pretty clear, but the work may well have been done in accordance with the normal practice of checking that approved materials were being used, and that using approved materials implied compliance with the regulations. That's a very, very common failing, as for years building inspections have been turning into a tick-box exercise, and the underlying law that they are supposed to be checking compliance with isn't always that well understood (as in the Grenfell Tower case, it seems). As a few here know I give expert advice in court, usually for insurance companies. There is an absolutely golden rule they stick to, and that is to make no statement whatsoever that could be seen by a court or jury as any admission of liability. As a final point, I'm sure that there will be a flurry of civil actions following the criminal cases. The burden of proof for a civil action is a great deal lower than for a criminal case, it is "on the balance of probability", not "beyond reasonable doubt". As such, an apology would almost certainly carry a great deal more weight as evidence of liability. I know the above sounds hard hearted, but there really are very sound reasons why all parties, guilty, innocent, liable and not liable, are very unlikely to make any form of statement that could possibly be interpreted by a court or jury as an admission.
  13. Plumbing 101: the absolute basics

    TBH, I've stopped using it for anything except permanent threaded (iron) joints now, as Jet Blue is far easier to use on compression joints, as it can be undone more easily. The liquid PTFE stuff works very well (but is a PITA to get out of the bottle) and if you want to take the joint apart you need to warm it up a bit, which makes the sealant go soft. Now I use a mix of PTFE tape on any threaded plastic fitting (there are a few of those in the water treatment system, on filters mainly), liquid PTFE on any threaded metal fitting that I don't think I'll need to take apart again, and Jet Blue on all other metal fittings.
  14. Plumbing 101: the absolute basics

    Nick, You could look at doing a version of what I did with our electrician, but with the client doing the heavy stuff and you imparting your knowledge. I'm pretty sure that one of the biggest problems many self-builders have when it comes to doing work themselves is a lack of confidence, as they are tackling something unknown. Just having someone around who has masses of knowledge and experience and who can help them tackle work they otherwise might not feel able to may well be something a fair few would appreciate, and pay for. In your case you may not have a properly working left arm for a while, but the rest of you still works OK, and the most important stuff is in your head, anyway. There has to be a way of using that to tide you over while your arm gets sorted out.
  15. Cheap 6KW ASHP

    No problem, if you include the window and door areas and U values I can work through the heat loss spreadsheet pretty quickly, and give some more useful data for you.