Jeremy Harris

I just love that you used Fortran! Last time I used it was Fortran 77 running on a DEC Vax, to model 3D weapon trajectories from an instrumentation pack that used three rate gyros and three orthogonal accelerometers, using the Runge-Kutta method to resolve the iterative problems created by multiple double integrations to derive position, when the weapon was rolling, pitching and yawing, so changing the accelerometer references with every sample. Oh what fun that was, when we realised that the model was unbelievably sensitive to the entered initial conditions. It started a whole new project in acquiring very accurate initial condition data. Your graphical results look promising, any chance of the source code? I've been looking for an excuse to install GNUFortran and have a play............................

Good point, Nick, I was unaware that some pressure reducing valves already have a gauze filter to prevent the "crud" problem. Is there a list somewhere of those that do, and those that don't? If so it could be handy. The two I have don't have gauze filters, I'll try and see if I can get the manufacturers names tomorrow. There are both the same, Italian made, 22mm compression fitting, eith a very fine thread. I've had one apart so know there's no filter in it (and, before you ask, I took it apart because I accidentally wound the adjusting screw off the end of the thread - my excuse is that it was in a very awkward place to get at!).

A simple Y strainer should do the job OK, I can't see a need for anything more expensive/complex, and it's all that our ASHP manufacturer asked for. I used one of these: https://www.bes.co.uk/plumbing-supplies/brassware/strainers

Not really when you have things like pressure reducing valves or thermostatic mixer valves down stream, as the last thing you want is a spec of scale or stuff jamming them up. The same goes for an ASHP or plate heat exchanger, it's good practice, and in some cases essential (as it's in the manufacturers installation instructions) that some form of screen or filter be installed to keep stuff out of the narrow passageways in the heat exchangers in these devices. Our ASHP instructions were clear that a Y strainer was the bare minimum on the return to the ASHP, just to stop anything getting back into it's heat exchanger. Congrats on becoming an aged Grandparent, BTW................................

The electronic heat control models,like the Stiebel Eltron DHC-E, will only use as much electricity as needed to deliver the set temperature, so if you turn the flow down on, say, a washbasin tap, then it will turn the power down in order to stop the water getting too hot. The fixed power models will deliver a water temperature that depends on flow rate, so close the tap a bit and the water gets hotter, open the tap and it gets cooler. Both will be similar when first turned on, in terms of heat-up performance. The difference is really like that between a thermostatic mixer shower, where the mixer tries to maintain a fixed shower temperature, no matter what happens to the supply water pressure or temperature, and an electric shower, where you have to vary the water flow rate in order to get the temperature you want, and may need to do that whenever anything affects the flow rate, like another tap being turned on, dropping the local pipe pressure slightly and reducing the flow at the electric shower, so increasing it's temperature, or the opposite when the pressure suddenly increases and the flow rate increases, making the electric shower run cooler. edited to add: I've just read that back and it doesn't seem that clear! If you think of a standard instant water heater as being like an ordinary electric shower (they are near-identical internally) and the electronic control instant water heater as being like a thermostatic mixer shower, that's what I was trying to compare above. Also, if you have vulnerable people around then the electronic ones can be a help, as they can be set to never exceed a maximum temperature, to avoid scalding.

As above, but there are broadly three groups of these things. Some have a small reservoir of hot water, in an insulated tank, and are intended for use with wash basins, for hand washing. They aren't true "instantaneous" water heaters, they are really just a miniature UVC with an electric heating element and a pressure release valve to deal with expansion. The second type are the ones like an electric shower, with a fixed, or hand switchable, heating element, that delivers a fixed amount of power to heat the water. Vary the flow and the temperature varies, so the temperature control on these is by varying the flow - if you want hotter water, cut the flow rate, if you want cooler water, increase the flow rate. The third type is like the Stiebel Eltron DHC-E that we have. It measures the flow temperature and adjusts the power to the element to maintain the set temperature, if it can. This means that it will, generally, have two advantages. The first is that, as long as the flow rate doesn't exceed the maximum, it will deliver water at a constant temperature, as set on the front panel, irrespective of water flow rate. If the flow rate drops, the heater drops the power to the heating element, electronically, to keep the temperature the same. The second advantage is that it will only use as much electricity as needed, so can be a fair bit more economical. In our case, it's a backup in case our thermal batteries in the Sunamp PV don't get enough charge. The water will still be pre-heated to around 30 to 35 deg C by the ASHP and plate heat exchanger, and all the Stiebel Eltron has to do is lift that up to 42 deg C, it's set temperature, that is the bare minimum we think is acceptable for hot water (it will just run a comfortable shower OK). At 35 deg C input temperature, the Stiebel Eltron only needs just over half the available heating power, at 10 litres/minute flow rate. If the preheat temperature drops to 29 deg C, then the Stiebel Eltron would be running at full power to maintain 42 deg C at 10 litres per minute. Hope this helps explain the differences.

I think that a lot of DIY plumbing installs don't need a "professional" to commission, though. In our case we have no boiler, an ASHP that doesn't require any paperwork, and the the same goes for the rest of the plumbing system; there are no items that need signing off, so a plumber never once crossed our threshold (just as well, as around here they are the most expensive of all the trades, by a massive amount - no offence to Nick!). If you need certification for any installed equipment, like a UVC, boiler etc, then I can see your point, but if not, then why not DIY the whole job? Plastic has de-skilled all the major work, and the only skills you really need to learn are working with copper pipe and fittings, which does require some skill and knowledge to do a good and reliable job. If you weren't fussed about appearances and didn't have a boiler or UVC to have signed off, then you could quite easily plumb an entire house in plastic and not need much in the way of skills either. Learning how to fit a plastic fitting properly, so that it will be reliable, takes most people at most half an hour, and there are no expensive tools to buy, just a fairly cheap plastic pipe cutter, a rule and a marker pen.

Yes, and it's a good idea, for the relatively small additional cost and bother of adding another bit of pipe. I did this for a friend, who's wife has MS, so that when she turned the lever-operated hot tap on the wash basin, the temperature was set to a safe and comfortable hand washing temperature. In my case, I've now got a higher main hot manifold temperature than I had originally (~50 deg C) and have TMVs on the bathroom and down stairs WC hot taps, fitted locally under the washbasins. I only added this as we found it nice to have hotter water in the kitchen and utility room sinks, yet wanted to keep the ease of having comfortable and safe temperature water at the washbasins. It works well, and TMVs can be had pretty cheaply. It also saves a bit of hot water, as it stops very hot water being wasted as run-off.

And just for those really serious about levels, the apparent slopes in that photo are mainly the camera lens distortion, because of the wide angle. The horizontal 15mm copper is dead level, the waste belo it has a 2 deg 'ish slope down to the left, the grey waste connecting the two sinks has a similar slope down to the right.

Ours is a lot more modest, with just two, four way manifolds, a H+C to each bathroom take up two outlets, H+C to the kitchen another two, and as the utility room is adjacent to the downstairs WC, they share the last H+C outlets. If you have the manifolds in an easy to access location (ours are mid way up the wall in the services room) then you have the big advantage of being able to turn a whole room off from an easy to get at place if there's a problem. This saves crawling around trying to get at ballofix valves that are tucked neatly away out of sight, in our case almost always inside fitted furniture. We also had the unusual problem of not having drinkable water on site to test the plumbing after first fix, because of our borehole problems. I didn't want to test it with water that may have been contaminated, so took the view that a leak in a length of pipe with no joins in it was a very rare possibility, and didn't test until second fix. Like others, I had no leaks anywhere from any of the plastic stuff, the only leak I had in the whole house was a poorly sealed 1" brass iron thread fitting into a filter. There is one slight issue with plastic, and that is that it's very hard to get it to look neat when it's surface mounted and visible. For this reason, I switched to short length of copper wherever a pipe could be seen, like in the cupboard under the sink, or the cupboards under the wash basins. It may be just a personal thing, but opening a cupboard door and seeing a less than perfectly straight bit of plastic pipe offends my eye. This is the cupboard under our kitchen sink, that shows where I switched to short lengths of copper:

The water company maps and plans are notoriously inaccurate we found. We were repeatedly told by Wessex Water than there was no mains water near us, When we came dig a drainage trench across the lane I had to ask every utility whether they had anything in the area we were going to dig, as a part of getting a Highways Licence. Wessex Water confirmed they had no pipes in the area. Luckily our digger chap knew how poor the info was from the utilities, so he very carefully scraped away the trench and lo and behold exposed a 1 1/2" cast iron water pipe running down the centre of the lane! We followed the line of it and found a Wessex Water cast iron cap over a stop cock, in the grass verge of a house across the lane. It turns out that this was their water main, put in in 1934, when the village first got mains water, but that had been changed in the past 20 years or so, as it had the Wessex Water logo cast into it, rather than the old water board logo. Now here's the odd thing. Wessex Water knew nothing of that water main, yet were charging the consumer at the end of it for water, and had, at some time not too long ago, replaced the stop cock! How on earth they knew they were a consumer, when they didn't know about their own pipe is beyond me, but it does illustrate how little faith you should place in maps from utility companies. As a final point, it's worth looking at where this runs, as it's old and it may be it runs to an old cess pit, rather than the main sewer.

As above, it really is a very straightforward DIY job I found. I know that some have reservations about plastic plumbing, in fact I did, and needed some convincing that it was OK. But, having plumbed a house with a manifold system, pretty much all in plastic except for the heating and hot water stuff, then I'd have no hesitation in saying it's a very easy skill set to learn. It was very quick too, because of the long pipe runs and the need for very few joints with plastic plumbing. That not only made the job quick and easy, it also gave peace of mind, as we have no pipe joints anywhere than aren't easily accessible. It's very reassuring knowing that long lengths of pipe buried in walls and ceilings have no joints that could fail at some future date.

Your best bet is to read those judgements and see if that makes sense in the context of the rulings. I have some doubts about it, TBH, but would be happy to be proved wrong if there is a clear statement in one of those judgements that could be used to support that argument. It's worth noting that local authorities are very lax when it comes to the law, I spoke to the supervisor of the person who was sent to climb over our security fence and across piles of rubble and steel reinforcement fabric to look in through a window, and she had no idea of the offences she was ordering her staff to commit. I'd treat anything on the internet, even posts on this forum, with a degree of caution, as very often seemingly competent posts can turn out to be incorrect. Unfortunately, the internet is a place where false information gets' spread around quickly, so there maybe many references that are the same, but all originate from one poor source. It's the reason I get so hung up on honesty, and make a point of correcting things I know to be wrong, really as a way of trying to break the chain of misinformation, or at least help to put things into context and ensure there's a better balance of views, especially on the law and risk, two areas I've worked with a lot over the years,

Sure, I can pretty much give chapter and verse on the law on this now! It's a bit complicated, because the Council Tax was rushed in to replace the Poll Tax, so the government didn't have time to create all new legislation. Instead, they had to come up with a way to value properties, in order to put them into Council Tax bands, and they did that by using an old law that was still in force, the 1969 Rating Act. This was the law that backed rateable values for the rates, and contained all the detailed definitions as to when a property was liable to rates and when it wasn't, along with a lot of other stuff. So, The Valuation Office Agency used the 1969 Rating Act as the basis for valuing properties and obtaining what used to be the rateable value for rates, but they divvied it up into Bands, under the new Council Tax legislation. Like most law, there is a statuary instrument, in this case the 1969 Rating Act, plus subsequent modifying case law, that together define, in legal terms, certain things. HerbJ came up with the relevant case law, in post on this incident on Ebuild. Here is a copy of that post that I've kept for reference: When I challenged the local authority, and quoted the law to them, and pointed out that in order to become a "rateable hereditament" the house must have a potable water supply, as defined in case law judgements that had refined the meaning of the 1969 Rating Act, they backed off, very quickly indeed. In my case, because we had a borehole, I was in a very fortunate position. Under the environmental health rules of our local authority, our private water supply was not deemed safe to drink unless it had been tested by a properly accredited test lab, or by the environmental health departments own testing facilities. I had the water tested by a former colleague where I used to work and it was fine, so I used it without any problems whilst we finished off the build. However, under the councils own rules, the water wasn't safe to drink, because it had not been tested by a properly accredited lab. Just before completion I got the environmental health people to come around and sample the water, and send it off to be tested officially, and it was only then that the house became eligible for council tax. As it happens, I received the test certificate from environmental health on the day of the completion inspection. I then wrote to the VOA, filled in a form and requested that they add our house to the list dated from the completion date of 30th September 2016. The VOA said they had a high workload, and could take several weeks to process our valuation request, and suggested than the valuation date be amended to 18th October 2016. I provided them with a stack of evidence to show that the gross external floor area (which is what they use for determining the value) would be impacted by our very thick walls, and included drawings with carefully annotated internal floor areas to illustrate this. I also got a bit cheeky and suggested that, in my opinion, it should be in Band D. Now, realistically, I knew we hadn't a hope of being in Band D, but were more likely to end up in Band F or even G, as the similar sized bungalows behind us are band G. I was a bit surprised to find that we ended up in Band E, and I couldn't, in all honesty, argue about that. Just after Christmas I received a Council Tax demand, backdated to 18th October 2016, as expected. I rang and asked if I could pay by instalments and they agree to three monthly payments, one a week ago, one in late February and the last in late March. However, I'm a bit peeved, as I put in a request for wheelie bins and recycling bins at the beginning of January and we still don't have them, which is nuisance when we've been paying for refuse collection (amongst other things) since last October. Hope the above is clear. If you read the linked judgements they also give other reasons as to why a property may not be a rateable hereditament that may be useful.

These work well, with one slight reservation. I fitted one around ten years ago in the ceiling of the bathroom of our old house, to switch the extractor fan on. I had a standard switched double gang13A socket in the loft, immediately above, so it was a doddle to fit the PIR sensor in the bathroom ceiling and wire it to the SELV transformer that powered the fan over the shower, at the other end of the bathroom. I disabled the PIR light sensor (it was one with a time delay but no light sensitivity adjustment by putting a bit of black paint over the LDR - safe and easy to do, and hidden when the thing is reassembled). This made it operate day or night, whenever anyone enters the bathroom, and has been very effective at keeping the bathroom free of condensation. The slight reservation is that it puts the fan on in the middle of the night, if someone pays the bathroom a nocturnal visit, and the fan then stays on for the duration of the timer. As it happens, with both the bathroom door and our bedroom door closed we can't really hear the fan, but with MVHR you may well hear a bit of noise from the bedroom supply terminal if it's on full boost in the middle of the night. Our MVHR is virtually silent normally, and there's no audible sound from the bedroom vents when it's running in normal ventilation mode, but there is a tiny bit of noise from them when it's on full boost. Whether or not that's enough to be a nuisance I don't yet know. Perhaps a PIR in series with an external time switch might do the job? That could be set so that the PIR isn't powered up at night, so can't operate the boost.

Anna, because you are building more that a single house and are VAT registered, you are a developer, as Jamie says above. The question WRG to CIS is then whether you are a contractor, or whether you are just hiring sub-contractors, If the latter, then you don't need to bother about CIS, if the former you do. Normally a developer wouldn't also be a contractor, the most common exception is probably small builders who build one or two houses to sell. Earlier today I saw the van of a local builder that I know does "speculative builds" like this, if he's still there when I drive past again later I'll ask him, as he's a nice enough chap and I've helped him out with some supplier advice, so he owes me a favour. As a developer it means you have to follow all the rules that apply to small developers and you don't do things with regard to VAT and other taxes the way a self builder would. You can't, for example, follow the guidance on VAT that applies to self-builders, but you can reclaim your VAT with your regular VAT return, so in that respect you are better off as a developer. However, there are also some downsides. Self-builders can get a self-build warranty from one of the warranty providers, you cannot and will probably have to register/join one of the warranty scheme providers in order to be able to sell the houses with a warranty (which is quite commonly a lender requirement). You can get an alternative to this, like an Architects Certificate or similar, but I think buyers might be a bit wary of a developer who isn't registered with one of the big name providers, like NHBC (not that for a moment I'd recommend them, my experience with them was dreadful)

This tallies with our recent ordeal in getting our VAT reclaim sorted (finally resolved by a letter received yesterday, nearly 4 months after I started the process). There seems to be a central government drive to get all departments to focus on collecting as much tax owed as possible, which is a laudable aim, but the way some departments are going about it is a bit OTT. I've already related the tale on Ebuild about out Council Tax snoopers, breaking in to the site at night, climbing fences, ignoring PPE warnings and (not wearing any PPE!) to look in through windows and see if the house was habitable enough for them to start charging Council Tax on. I got annoyed enough to formally complain, send a copy of the CCTV and legally deny access by the council or anyone they employed without my express written permission, saying that their breach of site safety rules jeopardised my site insurance premium and therefore constituted aggravated trespass. The stupid thing is that it meant that I had helpful advice from many forum members, including some case law on when a house became a "rateable hereditament", and so liable for Council Tax. I could then easily delay paying it by making sure that I didn't officially have a potable water supply in the house until just before completion. That meant they probably lost a years worth of Council Tax, simple because they'd annoyed me by breaking in.

Right, that's tomorrows experiment cancelled, then!

I'm definitely going to have a go with a pipe cutter tomorrow, just out of curiosity. I'm afraid I probably can't produce a great video, of construction channel standards, but I'll see if I can have a go at making one, as if it works, then it'd be useful to know, as a lot of people probably already have pipe cutters.

I posted this a couple of days ago in another thread: I live in a small rural village. There are three people who have woodburners who live here, and frankly they are a bloody nuisance. When the weather is really cold, the air in the valley is almost always stationary. We have a stream running through the valley, too, which creates a fair bit of fog/mist in cold weather. The wood smoke cools and sinks to the valley floor, then gradually fills the whole valley and all the houses in it with thick, choking, smog. The parish council have tried to intervene, to no avail. Thankfully the place we're moving to is a bit more enlightened. the topography is similar - small village in a valley with a stream, and the problem used to be the same. They kept "naming and shaming" the culprits, with photos of their smoke falling to the valley floor and filling it, until eventually peer pressure stopped them using wood stoves altogether. They did the same with bonfires too.

Anyone tried a decent pipe cutter? I have sheath strippers, etc, and up till now have always just trimmed the outer sheath back, used a sharpie to measure the cut point on the armour wires, wiggled the inner core around in a cone-like motion to neatly get the armour wires clear, then trimmed around the armour with a pair of sharp, double action, side cutters. Does a very neat and tidy job, but is a bit of a faff. So, looking at that tool, what happens if you ran a pipe cutter around the outer sheath, right where you want the armour wires trimmed, so that it scored the wires, then removed the excess sheath and broke the wires, as in that video. Then use a standard sheath trimmer to trim the sheath back the right distance back from the cut armour and cleanly removed the sheath (and I have to say my adjustable sheath cutter, with its sharp blade does a MUCH neater job of cutting the sheath than that tool does). From then on, it's assemble as normal, ideally with a Pirana nut rather than the banjo and crap nut the glands often come with. I may have a go with a pipe cutter and sharp blade tomorrow on a bit of scrap SWA and see if it scores the wires enough to get them to break cleanly. If it does, I'm going to kicking myself, very hard, for not thinking if this before, all the more so because I have a pretty expensive pipe cutter, that was one of the best investments I made, and if it can do this job as well then it'll be a real bonus. Also, I can't help thinking that a very sharp, hard, pipe cutter wheel may score the armour wires more cleanly than a bit of junior hacksaw blade, although I may be wrong.

I bought a Wiltec stainless brazed PHE, from Germany, the 20 plate, 44kW version, here: http://shop.wiltec.info/index.php/language/EN/cat/c511_Heat-Exchanger.html The reason for getting a 44kW, even thoguh at most it's delivering only a few kW, was to allow for the difference between the higher temperature difference used testing. I wanted as low a temperature difference as possible, and as the 44kW one was only around £50 inc postage, it made sense to go for that one rather than the one half the size.

Shouldn't that really be under their feet?.................................

I can say that my building inspector (and they sent their most senior bloke out for our completion inspection) wasn't the slightest bit interested in the pipe fitting, my water usage calcs or even the water testing I paid environmental health to do! He was in and out of the house in half an hour, and didn't even glance at the array of certificates and paperwork I had arranged for him in a neat pack on the kitchen worktop. He didn't even bother to take the copy of all the paperwork that I'd made for him away, but as he was leaving said that he'd email me the completion certificate later that afternoon! No excuse for not following the regs, and I'd gone OTT in making sure that everything was compliant and proved to be so, but it does show that they aren't always that interested in things like whether a particular valve is marked as being WRAS certified........................................

I can make what may sound like an odd recommendation for valves. I looked at the price of motorised ball valves and found they were expensive. So, 3 years ago I took a risk and bought a couple of 12V motorised ball valves from China. The risk was obvious, they may not have proper bronze or brass bodies, the plating on the ball might be poor, the electrics might be a bit grim, etc, but there were loads of them for sale from different vendors and they all looked identical. I also spotted them on a UK sold system (I won't name the company, but they are well-known) as a part of a packaged DHW system. They were so cheap that I decided to strip one down completely and have a really good look at the materials, workmanship etc. The other one I put on a rig and ran every five seconds continuously, from a timer, as a crude reliability test. I have to say that the valves were the equal of many manual ball valves from the normal UK suppliers (in fact better than some). I suspect that a fair few UK supplied ball valves are actually made in China anyway! After 7 weeks of continuously running the test valve every 5 seconds, 24 hours a day, it was still working flawlessly. So, I went and ordered four more, two to use and two as spares. The motor head can be replaced without disconnecting the water connections, and inside it the micro switches that control the limit stops are standard sub-miniature ones, as is the small relay. The motor and gear train look to be proprietary parts, but with luck they may not be the primary cause of any failure. I had the metals tested via a former colleague, and the spectroscopic report shows the brass to be of good quality. I sliced the ball in half and was surprised to find that it was stainless steel, rather than chrome plated brass. I can highly recommend these valves, even if the source does seem a bit dubious. I think it's a bit like a lot of Chinese stuff, there's a lot of junk around, but hidden amongst it are some good quality items at keen prices. They come in both 1/2" and 3/4" body sizes, and I've found that the smaller DN15 valves are absolutely fine for a low heat output UFH manifold and also fine for the 7 kW maximum from our ASHP flow to the buffer tank heat exchanger. The flow rate is a fair bit lower than the limit for a DN15 valve body for the sort of low power systems you and I have. Don't laugh, but I ended up buying them from Ebay, really because Ebay is slightly better than Aliexpress in terms of delivery times, I've found, plus, even though it's not great, Ebay do seem to have better customer protection than Aliexpress. EDITED to add: Sorry, I forgot you're looking for WRAS approval for potable water, mine are running an antifreeze mixture....................... FWIW, I'd say these meet the WRAS requirements, but they are aren't marked. The body is good quality brass, the ball is stainless and the seals are PTFE, so there's nothing in there to cause any problems, even if you live in an area with a fairly low pH water supply.