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MikeSharp01 last won the day on April 29

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About MikeSharp01

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    East Kent
  1. I still feel it is to, all intents and purposes, an open loop because the party will be over before the slab detects the party people but they will have been well cooked in their own body heat - I think Nyquist would have had something to say about this whole problem - well the aliasing and sampling bit anyway. This heating issue is one we all have, or will get it once the house is finished. Without an air temperature sensor, after all the actual thing you are trying to control, you won't be able to bring any third party system into operation to help with the rapid rise in air temperature - EG pull the MVHR into summer bypass & boost mode to deal with the at least the worst of the air temperature rise while the slab catches on. Even then you will need a watchdog on your system to ensure that the heat being removed by the MVHR, and unceremoniously dumped out of the vent, is not being made by a runaway UFH. Lovely and complicated!
  2. I guess if everything is perfect then your logic feels sound, other than it is rather an open loop - suppose you have a party and fifty people turn up? So it also look to me like you have answered your own question with a yes, its just where the control is happening that is the crucial point I suspect.
  3. Internet in the US shifts out of Neutral

    Tend to agree on the EU but not sure if some people in the UK don't hope for a bonfire of regulation post Brexit. Agree we mat be taking to US centric a view though.
  4. Newby

    Welcome to THE forum David. Always need advice round here on H&S stuff so that will be useful - the buildhub tends to be a self help group and advertising directly is frowned upon but contributing is not. Lets hope the business flies all the same - a new venture is always a sweet / sour experience but generally what does not kill you makes you stonger - back to H&S then, sorry.
  5. The US regulator has shifted the status of regulation around the internet out of neutral. This has the potential of profound implications I am not sure I can see any upsides for the 'little people' - somebody has said that regulating the internet, so keeping it neutral, is on a par with regulating water quality and Tim Berners Lee thinks thus: Q: Are there any internet-related laws in the United States or the UK that you think need to be scrapped? A: My concern is in America maybe, having been in a leading position really on the internet for a long time that with (the loss of) net neutrality it will…not really be an open internet. I talked a good bit to start-ups in Washington a couple days ago, and they were concerned that if the net neutrality goes away they will…have to negotiate it [their service] and have it unblocked by each ISP (Internet Service Provider). That will be impossible and very transient. Whereas if they had started their service in the UK or Europe…you just launch a new website. And you don’t have to worry about it being blocked by different ISPs. Their Obama-era regulations – rules about net neutrality – were very valuable in the U.S. and we should try to preserve them. (Source: HERE , 15.12.2017) I wonder how the hub feels about it?
  6. Designing a rapid reacting 'real' air temperature sensor

    As I don't need hundreds I will get the Farnell jobie and have a play with it. I can use my pico scope and laptop to log it and wait for a frosty day.
  7. I am having a 'discussion' with our BR supplier about what sign offs are included, what I can certify myself to their satisfaction and what I have to seek elsewhere. I guess its about having all the paperwork completed before sign off. I have my list but I am not sure it is complete so thought I would put it out there by way of checking: Windows install - so do not need installation by FENSA certified team. Electrical install - so I do not need electrical sign off by electrician (as it happens I will get this done by my brother-in-law) but for completeness it is included here. Gas install - don't think this is ever in the BR peoples scope as needs gas safe qualification. Oil fueled install - I don't have one but it is here for completeness. Solid fuel install - I don't have one but it is here for completeness. Pressure vessel (UVC etc) install - so I don't need a plumber to sign it off. Water install from meter. - not sure there are any regs here but just in case. Sewerage connection - so I don't need involve the water company, other than inform them. Waste water and general plumbing, flows & trap sucking ect - always assumed this was part of the sign off by BR anyway but could be wrong! Ventilation system balance - so I can do it myself. Ventilation system compliance - always assumed this was part of the sign off by BR anyway but could be wrong! Air tightness - So, assuming I can trace the pressure and airflow sensors to national standard, I don't need a third party to do this. Sound insulation - not sure even how to test this but can't be rocket science, can it? So I don't need a specialist again. CO2 Energy Performance certificate - I wanted to do these but as I needed the pre-build one quickly I have already paid for this and the final one. Water use certificate - I wanted to do these but as I needed the pre-build one quickly I have already paid for this and the final one. What have I missed - probably something glaring!
  8. How far can you get in an hour

    Yes the Maloo is not melow and the stag - provided it keeps going is far cooler!
  9. Is this rafter detail OK?

    PAD stone is only needed if the load is not supportable on the material as it is, your SE will probably have specified a solution for this (or should have) which may be just brick work or a pad stone - if you have no calculations for the beam's loading on the bricks it would make sense to get it checked, particularly if you are going to move it althoguh it looks about right to my eye, and counting brlocks its 7.5 blocks wide which is 3.75 blocks to the centre and it looks about there to me.
  10. Designing a rapid reacting 'real' air temperature sensor

    Thanks Jeremy lots to think about there but specifically, from above, I was trying to understand the cooling effect due to motion of the air around the probe. I seem to recall, and as I said Thermo 1 & 2 were not my favourite classes when studying, that the cooling effect of wind is about breaking through the boundary layer of air around the sensor and that the sensor cools more quickly but I cannot, for the life of me, quite see how the temperature can go below the ambient temperature of the air around it no matter how fast it is travelling although a pressure drop caused by the air rushing by might explain it.
  11. Crypto currencies

    AH that makes more sense so the mining on the reward bitcoins can only happen when the successful miner transfers them to others (sells) not as they are created (Allocated).
  12. Crypto currencies

    To begin at the end - most of us feel unevolved thats cos we hate change. Working back: You could set up to have a go at mining yourself or offer your computing horsepower to other miners - that is what they often do - rent other peoples CPU time to run the particular 'gold panning' techniques across the block (which is what you mine). Read THIS if you want to get an impression for how much computing power you need to mine a block - it is almost English! Mining is really just the art / science of securing a perfect HASH of the transactions, and previous HASHES, in the chain which would be easy if it were not for the fiendish bit. By stipulating the format of the HASH the bitcoin designer(s) ensure that confirming a transaction by creating a hash of the transactions, and all the previous HASHES as well, would be very difficult, and hence a lot of work, because essentially you have to combine the block and another string (I think of it as) called a 'nonce' that creates a HASH of the block and its hashes so far in the correct format. The only way to crack it is to literally 'guess' the nonce values until the HASH is in the correct format. All this guessing is called 'Proof of work'. Because you want to be guessing, hashing and checking the hash for the correct format billions of times a second you need formidable horsepower. Once you have a working 'nonce' you submit it, in a fraction of a microsecond to stay ahead of the competition, and the other miners can verify it and you get your bonus bitcoins - which have to be assigned to you and in doing so will create another set of blocks that can be mined. You can spot the challenge here perhaps in that every transaction of a bitcoin creates a new mining opportunity which, when completed, generates 25 (at current rates) more bitcoins. Other than mining I believe the only way to get bitcoins is to buy / sell them - into and out of your wallet. Well thats my understanding anyway - anyone got another?
  13. Designing a rapid reacting 'real' air temperature sensor

    Thanks Jeremy that feels a bit slow and I wonder how long it takes to react / rate of reaction to a temperature change in the air around it?
  14. As I was driving around Kent today I was musing on the car's exterior air temperature sensor and how fast it was, or was not, reacting to actual air temp changes outside the car. I know where it is in the car, down under / behind the front fairing and it must have some signal processing to smooth out the delta T's - observations seemed to say that the reading would update every 20s or so. I then started to wonder about the challenges of designing a very fast reacting air temperature sensor and logger that would display the curve of temperature as you drove into and out of valleys, across hill tops and through frost hollows. I then mused about 'wind chill' (Don't panic I know its not a problem for things without 'internal heat') and how the humidity / density of the air might cause a problem as it passed across the sensor as heat transfer, in theory anyway I think, will vary depending upon the density - If you think about it a bucket of water around the sensor will have more effect that a single warm molecule otherwise in a vacuum. I also dimly recalled my thermo dynamics studies (mostly asleep I think I was) and, way back at the turn of the century, noticing that side impact in cars was being measured by temperature changes, driven by the old PVT (Pressure Volume & Temperature) gas laws, in the door air, with only a fractional (1ms) lag behind what a pressure sensor could achieve. (I found a ref HERE). In then end, many of these effects and constraints demand a sensor with very low mass (I did not say thermal) in order that the work required to raise and low its temperature is very small. So I am now on the look out for a very low mass, and hence fast reacting sensor - any ideas?
  15. Plumbing 101: the absolute basics

    +1 to use plastic everywhere unseen - it is easy and although soldering copper is fun it is not as safe - you will need a heat resistant matt to protect any woodwork near where you are soldering, unless you would like the insurance company to replace the house along with the plumbing should it catch fire, as well as some flux along with the Torch and cutters @PeterW mentions. I, personally, don't necessarily feel that the Hep20 is the ONLY choice but if you go that way don't forget to get the unlocking tools - The John Guest (Speedfit) does not need a tool but does have locking collars which clip in if you want to be sure the fitting is locked.