SteamyTea

The formula you need is here: https://www.engineeringtoolbox.com/heat-recovery-efficiency-d_201.html

Exeter University took over Camborne School of Mines (just seems to be a cupboard of minerals now), but the guy running the course was important on the Channel Tunnel surveying team (think his name was Andy). Was 3mm in our case. Actually quite achievable and repeatable. After adding extra water with a dash of Fairy. For housebuilding, I would think that some decent matched tape measures, matching staffs, a large protractor, a long hose with clear ends filled with coloured water, a recap of SohCahToa, a laser level and some decent handwriting is all you really need. AND a fixed know point as a datum.

If you assume, that during the heating season, that the ground temperature is at 8°C, and your UFH flow temperature is at 32°C, then that is a difference of 24°C. Now if we assume that the floor insulation has a k-value of 0.025 W.m-1.K-1 and the heating season is 120 days (2880 hours). Then, for each m2 of heating area you get: So while there is diminishing returns on the insulation thickness, what has to be decided when digging, if the marginal costs. Reducing the losses, will also reduce the heating season, but that does depend on the performance of the rest of the building as well.

Well it is certainly that. Are you in a very hard water area?

When I did my surveyors course, most of the work was checking, then double checking, then triple checking. When measuring levels we had to take 3 readings, which is actually 6 as we had to turn the leveller 'upside down', while someone else moved the measuring staff back and forth. (I was told that in the olden days, the OS used to take 7 readings, which is 14 really, but where allowed to drop 1, leaving 13). Once all the readings were taken, we then had to do loads of mathematical corrections to make sure that the levels made sense. Then we had to go out and do it all again. I actually quite enjoyed it, but we did have 2 weeks of good weather. If it had been raining, and considering it was at Exeter University's Tremough campus, it would have been miserable. I did not enjoy my time at Exeter.

5

I took a bus 2 summers ago, it was horrible. I think down here, I qualify for a pass.

Seems to mean that the regulation of building structures have changed regarding fire, MCS has had lots of meetings and told BSI that unless they (BSI) issue certification, they (MCS) will have trouble fitting systems. So normal buck passing by MCS. So if you are installing, via MCS, you can only fit the modules that have been certified (the 4 on the list).

You a fossil or got gas?

Generally no. There may be a limit to how much you can export from your battery, but you would not be exporting (usually). This is where V2G and home battery storage differ. The G is for grid. Would be V2H, which I think exists otherwise.

I would assume, which is a dangerous thing, that the combined input for each phase, would be the upper limit. So if you are allowed 6 kW/phase, and the V2G is say 2 kW, then your PV can be no more than 4 kW. (It is actually amps they look at, but using rounded up kW makes it easier to visualise) Are these V2G controllers 3P?

Just an engineering point. This is not about structures 'melting' or burning though. It is all about how they fail over time. Very few things fail explosively, thankfully, most deform in a predictable manner (cars are a good example). This is a good, basic, tutorial. https://feaforall.com/failure-modes/ Failure Modes: Understand the 5 most common failure types February 15, 2017 by Cyprien 31 Comments Many engineers I meet don’t know there are several failure modes… http://feaforall.com/wp-content/uploads/2017/02/cracked-beam-300x171.png Beam failure (not intended to be realistic ;-) ) They think: « That’s pretty simple… you apply a load, the load is too heavy, so your system fails and breaks… » Ok. I acknowledge that this is obvious… systems can break under a heavy loading. In fact… even a 3 years old would understand this logic. BUT… That’s not all! Don’t wait to have a big security problem in your system to finally try to understand what’s going on… Let’s discuss together some of the major failure modes. Just a note before starting with failure modes: That’s a LARGE topic with an awful amount of crazy knowledge to understand. That’s why I’ll only be mentioning the most obvious things… because my purpose is only to make you AWARE that those problems even exist …Hoping that if you are concerned by one of these failure modes , you will do your own research to understand. Why do you need to know about failure modes? If you are still wondering that, here’s the most straightforward answer in the world: You have to be able to see how a system can fail to improve it and protect it against potential failure modes. Don’t wait for it to break down to take action. (That’s what most companies do though… and that’s when they start to realize they might need to use FEA to find out the cause.) What are the typical failure modes? Let’s see that now 1) Fracture: When cracks appear I guess that everyone saw some cracks in a bridge or in a wall… well, that’s a sign that the structure has a problem! http://feaforall.com/wp-content/uploads/2017/02/Crack-in-the-wall-300x279.png When a new cracks appear or existing cracks are extended, you are basically looking at a fracture mechanism. Not every part fractures in the same way: Some parts fracture slowly and deform plastically before seeing a sign of a crack… that’s because those parts are built in a ductile material. http://feaforall.com/wp-content/uploads/2017/02/ductile-failre.png Ductile fracture with characteristic distortion and shear lip Steel is basically a ductile material. It extends and deforms before failing. That’s why the stress-strain curve is like this: http://feaforall.com/wp-content/uploads/2017/02/stress-strain-curve.png Now… you have also brittle materials! Those are much more « sneaky » if I dare say Those materials tend to fail suddenly and abruptly without showing any sign of plastic deformation. Concrete and glass are 2 examples of brittle materials. Note that you have also materials which a ductile up to a point and then become brittle. Some materials like bone can be ductile or brittle in function of the strain rate ( Source) Here’s a picture that shows the difference between brittle, ductile and semi-ductile materials: http://feaforall.com/wp-content/uploads/2017/02/brittle-and-ductile.png Want to see how a real beam fractures? Watch this video (you can skip just to watch the interesting moments): How do you simulate fracture with FEA? Well, that’s a difficult topic so I won’t talk about it now, but that’s really something that deserves your attention to study. You will find fascinating theories and algorithms to solve fracture problems… a lot of them being still very experimental. (If you have something to add to that or experience with fracture simulation, please write it in the comment section, that will be useful for everyone reading) 2) Yielding: When a body experience stresses Yielding is probably the most common type of failure analyzed with FEA It describes a body which experiences stress in excess of the yield stress. Yielding is only called yielding when it actually compromises the integrity or function of the part that yields. Why do I need to precise that? Sometimes you may observe a « localized » yielding that cause strains near stresses concentrations in your part, but then… the stress in redistributed and the yielding actually stops. How to simulate that with FEA? The most simple type of analysis, the « linear static » analysis, deals with this kind of failure mode. Nothing too complex, just normal FEA… and a lot of engineering judgment. 3) Insufficient Stiffness (Deflection): When flexibility causes failure Whatever the mechanical system you build, it must be stiff enough to resist the loads. Seems pretty basic, but that’s really a notion at the heart of mechanical engineering. It was also probably one of the first lessons I learned when I used FEA for the first time in my life. http://feaforall.com/wp-content/uploads/2017/02/Capture-d%E2%80%99%C3%A9cran-2017-02-14-%C3%A0-12.10.15-1024x685.png The system you see here is a mechanical system I was building for a student project when I was in the Ecole Centrale of Lille in France in 2006-2008. If you are wondering what it was supposed to do…well, a scanner was placed at the center on a mobile platform and a rotating arm was supposed to take the sheet going out of the scanner and store it in a removable tray. The part on the top-right picture was supposed to support a big ring of steel of 50 cm diameter and around 3 kg. I designed it the most simple way I could at that time… a sheet of metal simply folded in 3 pounded to make a big hole. Then when I had to BUILD this system, I realized that this part was bending with a deflection of something like 10 cm… How I used FEA to solve the problem The consultant supervising my team of 6 people told us something I still remember back now: « Your part is bending because it is not stiff enough, if you fold it again a second time in other direction, it will become much more stiffer…. » That’s when I had the (brilliant) idea to come up with a new CAD model design that would solve the problem… I didn’t have much time because the project was due in 2 weeks… so I decided to use FEA to solve this problem (before doing the testing… gaining around 1 week of time) I simulated the part and the FEA software told me that the maximum deflection would be 2mm … probably not the best I could get, but acceptable… I built the new part and tested on the system…and it actually WORKED. Man, I was stunned. I thought to myself: « This FEA stuff is quite something, I’ll have to dive deeper into it when I get the time » By the way, If you don’t believe that I built this system, here’s an actual proof ;-) http://feaforall.com/wp-content/uploads/2017/02/cyprien-armadocs.png If someone tells me how I can get back this hair, I’ll pay you a beer! (Don’t tell me surgery, haha…) Ok, I was on the road to explain you the different failure modes… back on the road 3) Buckling: When a loss of stability creates big damages… http://feaforall.com/wp-content/uploads/2017/02/04ecca04-30ec-4a79-ac9f-eb4429265117.jpg In a nutshell, buckling a kind of failure that happens to certain types of slender geometries because of the inner instabilities that occur in the loading. In it very dangerous because buckling failure can happen much before the material failure (Yielding). I won’t talk too much about this failure mode because I already wrote some much more detailed article just about it here: http://feaforall.com/buckling-simple-explanation/ Another important point about buckling is that it is not detectable in FEA if you are just performing a linear static analysis. You will have to perform an actual « buckling » analysis to see its effects (and that’s why knowing about it is important) 4) Fatigue: When time causes a loss of strength When you hear a story in your family that they were driving the same car they drive for more than 10 years and suddenly a part failed and they didn’t know why… That’s probably because of Fatigue! Fatigue is a failure mode that takes a lot of time to happen. Basically, you can understand it like that… When you use a system, even if it is designed to be resistant enough to the loads applied to it… after some cycles of loading, the parts start to lose strength and become weaker. A typical fatigue failure of a part looks like that: http://feaforall.com/wp-content/uploads/2017/02/Fatigue-cut-300x218.png Part which failed due to fatigue How do you simulate Fatigue with FEA?? I have an old guide that explains simply the principles behind Fatigue analysis. Join my newsletter here and I’ll send it to you (along with other free material and courses) [optin-monster-shortcode id=”aereopxpatfcxnuc”] 5) Creep: When a body deforms over time Those analyzing concrete structures like bridges or buildings know this mode of failure very well. Creep is simply the natural tendency of some solid materials to move slowly or deform permanently under stress. It is increased when the materials are heated (the extreme example is when steel is melt under high heat to make it change shape) http://feaforall.com/wp-content/uploads/2017/02/12059701-email-dsc00332-2-300x225.jpg Creep failure of a pipe Creep is far from being negligible as it is involved in many accidents around the world. For example, some experts say that the collapse of the world trade center was due to Creep (Search for the word « creep » in the article to find the explanation) How do you simulate Creep with FEA?? Creep is generally handled by a special type of material model in your FEA software and is still very experimental. There are many different creep models available which depend on the kind of model you have. Creep generally happen over a very long time period, thus it is very difficult to observe in reality or to make theories about it because the scientist will have to wait years before seeing results. Same for FEA, even if you have creep models and you can theoretically simulate creep, you have to be very careful about the accuracy of those results without any experiment coming to prove that they are correct. (If by some chance you have some experience in creep and you have something to add, please enlighten everyone by leaving a comment about your experience.) Can several failure modes happen at the same time?? Yes, it most engineering problems, that is what happens… that’s why it’s alway important to review the data and try to spot all the possible signs of any failure. Good luck with that! /////////////////////////////////////////////////////////////////////////////// You maybe noticed that I wrote a lot of great educational article… that’s because I really want to contribute and help engineers who are new to FEA to understand those concepts better and faster! I am not hiding that it takes a lot of efforts to write all that, so…

I am surprised that the 'lime brigade' have not made a suggestion, they claim so much of it. That is interesting. I firmly believe that it is not the cement, or lime, itself that is the problem, but more a case of what it is mixed with and in what ratios.

I hate seeing statements like that. Would rather see engineering first approach.

Just about to open my bill and pay it.

Over the last few months I have noticed that my autofill/autocorrect, on both the phone and PC, are putting in random words and phrases. Is it Google and Microsoft playing about with AI.

Hopefully. We have about 90 GW of conventional generation in the UK, our current demand is 41 GW, so rather a non story.

Do you mean OCGT there (open cycle gas turbine).

You are referring to someone that is currently struggling getting date from some ESP2866s to a Raspberry Pi Zero W. Nothing is a (expletive deleted)ing giggle at the moment.

There are huge hidden costs though, even in the countryside.

Yes, a few years back, and it is why I am still using resistance heating. I started my energy monitoring over a decade ago, because I wanted to know if I would be better off on a flat rate as opposed to E7. Why I am still on E7. I have not run the numbers in the last few years, but doubt it has changed much. The big advantage of resistance heating is that repair/replacement is very cheap. Only had to change the DHW element, but as the cylinder was leaking, I changed that as well, but that was after 33 years of daily usage, cost less than £300 (got the cylinder of @Nickfromwaless mate Trevor). One of the problems I have is that I live in a warm part of the country. I am only have the heating on for 8 to ten weeks a year, with a bit of fan heater usage when needed. The other problem is that my usage is low, generally less than 15 kWh/day in the depth of winter, which sometimes drops below 8°C down here. The biggest problem is that I never meant to be in this place for 20 years, was only a temporary move while I retrained as a teacher, then back to Hertfordshire. Well that is what I told my then girlfriend. When I move next time, I shall invest all my cash in RE, insulation and airtightness, and an EV.

Explore the rules about fire safety, that should trigger a bit more official investigation.

Short belt up the M1. For me to get to Bristol is further.

I got one from The Range for £9. It is just a 400W fan heater. Works well, but a bit noisy, so sticking to my old fan heater as it is a lot quieter. This last week, which was very varied in temperature, cloud cover, wind speed and rainfall, I heated my house with 20 kWh or finest electrons. This may well be the first year I get to December without turning the storage heaters on.

Ask anyone from St. Awful to smile. Then duck out the way.