TerryE

On the subject of crap Eurolocks, do you ever watch any of this guy's posts: Youtube -- bosnianbill

Surely there are two separate issues here: The curb included 6 dropped curbs not 7 as you wanted, but the the contractor said was an agreed spec with the council. I've just had a look at ours that was put in a couple of years ago and we have 4 dropped curbs (+2 sloping curbs) and that is pretty standard on our road. Even the pub oppose which regularly has HGV3 deliveries only has 5+2. The work isn't to an acceptable standard (and which you first mentioned a few hours ago). I don't think that you should confuse the two. By all means don't pay until shoddy work has been rectified, but in my view at least you won't help by conflating these. But from your blog, your site entrance is crossing an adopted pavement onto a class B or C road, so I can understand why the council might insist on entrances conforming to their guidelines: If you want to revisit this then surely this is a discussion to have with the highways department. For example if you own the entire frontage then you might get them to agree on the grounds of increasing ease of turning onto the road, but the LA will have all these guidelines online, anyway. For example, our LHA has a guideline that vehicular access for a single dwellings should have a maximum width of 3.7m at the highway boundary, and limit drops to the corresponding number of curbs. Your best way ahead is negotiation, not confrontation. If they say that there isn't this 5 curb limit, then you can call the contractors bluff. BTW, your blog is a fantastic resource for anyone interested in the life-cycle of an MBC frame and slab self build. Have you though of adding it as link in your signature? (Look at the top RH drop down, and pick account settings -> signature and paste the link in there using the link button.

You don't own the bit at pavement or verge between the physical boundary of your property (e.g. the front garden fence) and the road. This is still classed as highway and the local authority does. You are crossing their land subject to their permission. The basic rule is that so long as the highways dept and planning OK the work, then they maintain a list of approved contractors who they license to do the work, so long as your pay for it, but it's their land and they have design authority. They maintain their own guidelines to standardise on openings and variation is usually a result of negotiation. This is the process that you described in your first two paragraphs. I would be deeply suspicious of any cold caller and the claims that he made. The authority take a very dim view of unlicensed and unapproved work on their property. They might require you to rectify such work by one of their licensed contractors at your cost. They also have quite a few ways of making your life hell, so tread very carefully

I do think that we are converging in our thinking. If you go back a year or 18 months, you (Jeremy) and I were having a debate about whether or not a buffer tank and what I would call micro blending is necessary. Is having complex sensing in the slab necessary? I've reach my own conclusions in 3 three broad steps: Researching your and other's experiences and designs and looking at them critically. This lead me to the tentative assertion that a buffer tank isn't really necessary, nor is a power limited control necessary. You can just treat the slab as a 17 tonne storage heater which you warm up a few degrees overnight. I then did some reasonably detailed modelling of the time varying dynamic of the slab, and this was enough in my mind to confirm these assertions, but modelling is modelling and also needs to be validated by real-world data. Hence my decision to add reasonably extensive instrumentation to see if my heat chunk approach where I essentially use my slab as a storage heater behaves as I modelled it. In a nutshell it does. It has always been my intent, as documents on eBuild and here, to run my system experimentally for the first year with extensive instrumentation to characterise its performance, and then to implement a final "production" control regime based on this experience. But by doing this process, my final system won't be an act of faith, but an evidence-based and informed implementation. Other's can copy the end-design if they want and skip 1-3, because someone else has done it. In my case I can happily treat my slab as a storage heater. I just have to be a little careful to put the right amount of top-up heat in each night. In terms of the relay version, I think that it would look something like this: The alternative would be drive all of this logic at 24V DC with low voltage switches and a 2P/NO relay and use it's output to drive the SSD.

@jack this looks a bit like Node Red to me

On a separate note, @Pete and his wife came to visit our house and look at our CH / DHW design. After talking to him, it struck me that you could always do my basic slab heating implementation microprocessor-free with programmable timer to supply the on trigger, and a remote thermostatic switch to supply the on-temperature break and a 3 pole 240V / 240V contactor to do the latching circuit logic. Some to discuss over dinner tomorrow night, I think.

Another member here, @RandAbuild, has a 1½ storey build (a rather tall 1½ storey build) and his MVHR is in a cupboard off the upstairs landing. Nice and accessible.

@MikeSharp01 Mike, if I could summarise my architecture, it is: Do any H/W connecting with off-the-shelf (OTS) components / devices that can talk MQTT if cost effective. Do any custom stuff using ESP modules sitting on a largely passive board which does wiring to connectors and keep at least one spare for cold-swap on failure. In the case modules like the ESP at least half a dozen. Have a dedicated IoT Wifi service for all remote devices ESP or OTS, or json over USB virtual serial in the case of essential services where I don't want the WiFi dependency. Use Node Red, MQTT, and a MySQL InnoDB database as the main applications platform to glue everything together. Use a minimal headless Linux server to run [4]. This has to be connected to the both the Home Network and the IoT network. This is the only device connected to both networks and routing between them is not enabled. The Node Red UI only listens to the Home Network on a non-standard port MQTT listens serves both. This one I don't like and need to thin about. MySQL only listens on a Unix socket and so is not available off server. I have a small number of web scripts on another non-standard port. The only other open port on the server is SSH on a non-standard port; certificate only, no password-based logon. Because of [2], the server really only needs RAM, USB and networking to work reliably. I don't make use of any fancy hardware such as graphics acceleration, GPIOs, etc. I also use a very stripped down version of Debian server. For example no Apache2, Samba , FTP or the like. If I could get a 2Gb RPi then I'd use that, but really the hardware is a detail and moving to a new SBC pretty trivial. BTW, I would prefer to use HTTPS on my Home network, but certainly Android / Chrome doesn't have a simple and robust way of allowing you to self-certify for your own server on 168.192.1.250, say, for access from 168.192.1.* only. Google really want you to use the cloud for everything, so chrome doen't play nice with self certificates. With enough InnoDB pool, the server will does bugger all I/O (just like the VM running this forum), mainly just flush updates through the file system, but IMO its just easier not to have to denormalise schema for performance. If I am taking temperature samples every minute then that's ½M rows a year per sampling stream. Seems to many to me, but ... Need to ponder more. I might need to move to a different no-SQL DB for the raw historisation data. Well as I said in the intro Jan and computers don't mix; she a pure user. I need (i) a backup who understands my system; (ii) a cold-swap spares inventory to cover the expected life of the system. My son-in-law was a sysadmin before he became a manger of the same, but he still gets his hands dirty and is into this sort of stuff so my aim is to have it so he understands the system. I really don't think that moving to a commercial system such as Loxone helps. For example, citing one one member here that I know uses it, does @jack's wife understand enough about his Loxone setup to maintain his system if he fell under a bus, and what happens with his system in even 5 years time and when there are no spares are available for this generation of system? Can I take your other point on the DS18B20 thread? On reflection, I've also decided to try the single RPi3 config to see if I have any performance issues before swapping to a higher RAM SBC.

Timber frame and eco joists give you loads of room for pipework and ducting runs. Use Aluminium cladding for all your Soffit and Verge work: zero maintenance and a softer look than uPVC. Ditto use AluClad uPVC doors and frames. Zero maintenance unlike wood. Continental-style windows (e.g. Internorm range) which open inwards for cleaning. Use a Hep2O manifold system for your plumbing. Put a small central service cupboard on the ground floor with the manifolds near the ceiling. No hidden joins in any pipes -- so no hidden join failures in later years. And you can isolate single appliances / sinks with a couple of turns of a valve in the manifold if you do need to do maintenance. In include your loft in warm space and have a proper staircase up to it. The MVHR can go on the floor in a loft room. That's just for starters.

I've got a smaller one on our kitchen outlet. The good news is that this saves a lot of fat going into the sewer. The bad news is that no matter how careful we are at avoiding pouring fat down the sink, I still need to clean it out every year or so. A nasty smelly job which yields a gob of fat about the size of 4 blocks of lard, but a lot smellier! Nasty job!!

+1 to Peter's advice. Hiring the right tool doesn't cost that much. A lot less than dealing with a badly broken wrist.

Yes. The onewire architecture used by the DS18B20s is a bus architecture. You can daisy chain dozens of thermometers off a single IO pin. The protocol enables the master to enumerate all device addresses and then it can send commands to all, e.g. "start a temperature measurement" or individually "thermometer XXX, give me your reading". Each thermometer has a unique address. Likewise I²C is a bus architecture using 2 IO pins. The ESP can only drive 3.3V @ 10mA, but the Crydom relays need a TTL level at a minimum (5V 40mA) so I use an MCP23008 IO multiplexor to generate these TTL level outputs. This hangs off in I²C bus so this is a 4 outputs (in case) for 2 pins as well. I could drive 32 IO pins off a single I²C bus this way, but I don't need to. So yes, in fact a single ESP module easily has enough IOs to do what I need.

I've got the first iteration of my House system up. It's really too modest to call a Home automation system, as the whole concept is a bit of an anathema to Jan. If I try to have a conversation about any of this with Jan, then her eyes start drooping and her chin dropping in under a minute -- far more effective than sleeping pills or hypnosis. What she wants is a big nob on the wall. (Anyone heard that before?) By way of context my overall approach currently is to use SBCs as headless servers to do the serious processing. These have no realtime I/O functions as this is handed off to dedicated ESP modules to handle the IoT stuff (in my case, though you could just as easily use Atmel/Arduino, RPi0 or equivalent off-the-shelf modules for this). All of my IoT devices are isolate from the House Enet and internet. There is no routing path between. They are on a dedicated private IoT Wifi service which is not advertised and has a nasty password that even I can't remember. There is however a Node Red /broker SBC connected to both networks and its HTTP based UI is access path to the IoT devices. I don't use TLS on the IoT Wifi, as I am not concerned about eavesdropping, however any sensitive data elements are encrypted and all packets digitally signed to prevent injection. But the main thing that I'd like to discuss here is the SBC side. To be honest I am a little dissatisfied with the RPis in this role. I currently split the work between 2 RPis, but since this is a 95:5% split, having the second RPi just complicates things. It is a lot easier just using one server to host Node Red, the MQTT broker and a database. Node Red is an amazing package, but this is really the subject of another topic. But can be a resource hungry if you are not careful, and if I want to store all historic data then I need a decent database and HDD / SDRAM capability. The problem here isn't so much the speed of the RPi CPU, but its limited RAM and the USB2 constraint. I already use a headless configuration on the SBCs using a stripped down Jessie server configuration, but I need a reasonable amount of RAM to run a MySQL InnoDB engine and the node.js pool. And it world also be nice if HDD/SDD performance wasn't USB2 limited. Having reviewed the options, I am going to try a ROCK64 4GB single-board computer which costs £57 including shipping as compared to the RPi at £35, but the Rock64 has 4× the RAM, a USB3 port and it benchmarks at roughly 10× the speed of an RPi3. The CPU speed isn't so much of an issue in this case, but the RAM and USB3 just gives me so much more headroom. It can also boot off eMMC which is faster and more reliable than microSD (though I'll probably just stick with microSD as the root partition will be on the HDD anyway). This Rock64 does have a few downsides: the support and community isn't nearly so strong as for the RPis, but for a basic headless server, it should be fine. There's no on-board Wifi, but there is a second Gb Enet port brought out to the second on-board header so I can just directly connect it to both my main house hub and my IoT Wifi hub. Anyway I'll keep you posted if anyone is interested. Some background context, which can be skipped if you aren't interested I use Wemos ESP8266 modules for all of my I/Os and sensors. These are cheap (<£2 each) so I buy them in lots of 10. This £2 module includes USB power/serial port, Wifi, an embedded flash-based file system and a decent amount of I/O. This is for a few of reasons: I am one of the core developers one of the runtime systems (Lua) for this device as a hobby, so for me it makes sense to use it. When you are breadboarding I/O stuff it is quite easy to fry a GPIO buffer or other board component. At £2 when you've got a dozen spare, this is a shrug; toss the chip and reach for another. RPis cost ~£40 so I don't hold may spares and crisping £40 makes me cringe. Sonoff also do a range of devices, plugs and switches which use the ESP8266 internally so I can buy these and reflash the firmware with my own build. All ESPs are served by a provisioning system, so I can update their Lua applications code as needed (hands free; the chips have embedded Wifi). I currently use 2 RPI3s: one to act as a Node Red / MQTT broker. This has a USB attached HDD. one to control the two ESPs which drive all of my CH and DHW sensors, flow meters, relays, etc. This is second is battery backed. My maintenance policy is centred around keeping a full spares inventory of any modules and SBCs so I can do a quick cold-swap on failure. Overall, I am happy with this approach. It is low cost and very flexible. The ESP mother boards (my equivalent of custom PiHats) are current Beta revs, and I have some changes planned. For example I use two ESPs for my DHW/CH control, but I have decided to consolidate all I/O onto a single ESP as one can handle this comfortably. I also implement a set of safety rules at the ESP tier that are independent of the Node Red Flows; for example: The Willis heater won't turn on if the pump isn't running; it is automatically turned off if any slab return is > 30°C or the Willis chamber itself is >35°C.

As a footnote to this thread, I've now got my cheap Chinese DS18B20s installed in my heating system, so for example I monitor the UFH and the slab by using aluminium foil to wrap and secure the canned DS18B20s to the PexAlPex pipes about 10cm from the manifold fitting, and then secured the foil in place with aluminium tape. I also cut an internal slots in the pipe lagging so that the Thermo is intimate the UFH pipe and surrounded by lagging. When running the water on loop without heat the thermometers all stabilise to within 0.2°C of each other, so the thermometers seem more accurate than my calibration process, Using the delta from the average circulation temperature as a trim adjustment seems to give extremely consistent results with the thermometers being agreement to better than 0.1°C.

If you assume that the external house surface is at external ambient and the external skin is an essentially impermeable barrier, then wind will have three separate effects: if the skin surface is wet and the air humidity is less than saturated, then you will get evaporative cooling which will reduce the skin surface temperature below ambient and there increase heat losses. If the house is inherently leaky then small pressure differentials across the house will severely increase such air losses which bypass heat recovery. Particularly if the MVHR inlet and outlet are on different walls then any pressure imbalance will degrade the effectiveness of the heat recovery. I've put both our MVHR inlet and outlet on the same gable to minimise the third, but where we are we rarely have strong winds. In Jason's case, I would have though a good place to put the MVHR inlet and outlet would be in his sheltered "alleys" between the two wings of his house which would shelter them from the worst of air wind effects.

Peter, given that you have a buffer tank, this is functionally the same. We did the sums and it made sense for us to use E7, but even if you are on a single rate tariff then putting 6-7hrs of heat a day @ 3kW will still make a big difference in warming up the house and the slab, and it represents a small start-up cost even at £3 per day. Jason, surely you still need to have a method of sizing the chunks and linking these to the incremental heating need. Yes, you can use a timed heating interval, but how do you decide the interval? Putting digital thermometer on the return from the slab and using a threshold is a simple and robust method. I think that Jeremy is correct here. Because I monitor the circuits separately I've noticed that they aren't quite balanced so one zone is about ½-1°C hotter than the others by the end of the heating cycle. Yes, I need to balance the zones, but after a couple of hours of circulation the difference between all the zones is less than 0.1°C, so the circulation really does rebalance the heat through the slab. The pump is barely audible in the toilet at a medium setting and the 40W ultimately ends up as another kWhr of heat going into the slab. OK. it might not make sense running the pump continuously on days when we are not heating the slab, but I think that running a 30mins on, 90mins off cycle is still probably worth it to keep the slab balanced and redistribute solar gain hotspots.

Even if you have gone the ASHP route because your house is at a different sweet spot, I would still suggest that the chunking approach is a lot simpler than having a buffer tank unless you also want to use it for DHW preheat. I would also suggest that you include a Willis heater, simply because this fall back means that your ASHP is no longer a critical element. If it fails, then even if you take two weeks or a month to repair / replace it, then you will still have a warm house, albeit at the cost of a few £s a week extra electricity. So spending £300 a year on maintenance contract becomes optional. You can do the routine maintenance yourself and fix when broke.

In our case we have a good passive-class internal frame and stone skin, so it takes about 2 days for a step change in external air temperature to effect the internal temperature. There is no point in trying to forecast or even to measure external temperatures, IMO. Quite a few weather services provide localised feed APIs which are zero-cost and good enough.

Nick, you might be interested in though I am covering the actual details on the control system in the next part. No Loxone or the like just a couple of RPis and ESP8266 modules at the moment. I've used the ESP modules because I am more familiar with hanging OW bus, GPIOs and other sensors off them. Also, if you get a polarity wrong during testing and fry an ESP module, they costs less than £2 to replace -- though now that the I/O logic is stable, I could do all this on a Pi-hat to the second RPi, but why bother? Given that in our case raising the overall house temperature by ½°C per day would double the daily heating requirement, I feel that using something like an internal air temperature as the primary control sensor is a mistake. For example, we've had carpet fitters and workmen working in the house over the past couple of days. You just can't go around after these guys closing outside doors and nagging them when the are going in and out, especially when the house isn't really occupied and it's only going to add pence to the heating bill. Having the front and back door open for half an hour is an effective way of dropping the hall air temperature by 5°C, but the last thing that I'd want to happen is for the heating system to go into overdrive to compensate. Turning on the slab heating won't make any material difference for 3-4 hours And by that time, (with the doors shut) the house will have largely recovered to its average temperature anyway, so the slab heating will only cause an evening overrun. If I do want to use a ambient temperature estimate independent of slab temperature then in my view it would be better to measure the temperature of an internal plasterboard wall and use its physical characteristics to filter out any higher frequency temperature variations that the heating system can't respond to anyway.

This is the Part II roll up of a couple of earlier blog posts and forum topics which provide the groundwork and context. Plumbing Design – Part I Heating the Slab – an overview Modelling the "Chunk" Heating of a Passive Slab Another DHW / DCW / UFH design. in summary, so far into commissioning and early use, everything is at least achieving our expectations and the house might in fact perform better than my predictions. The key design points that I listed in part I seem to be spot on. I want to compare a figure that I gave in the modelling topic with a corresponding plot during commissioning and testing to underline this: The first graph is a theoretical model based on a few simplifications, and the second live data, warts and all, and complete with hiccups as I test and restart the control system. The bottom line is that the slab is reacting exactly as I modelled in overall behaviour, though one of the parameters is different. The UFH pump at its medium setting is under half the modelled flow rate, increasing the delta temp between out and return from 2°C modelled to 5 °C measured. However, I decided to stay with this setting because the pump is almost silent at its medium setting, and the system and its subcomponents are still operating well within specification at a delta of 5 °C. So in my view, if you are building a house with near Passive performance (wall, and roof U values < ~0.15; windows < 1 and not too much area; well sealed warm space and MVHR; decent insulated slab), then you should expect heat losses of less than 40kWhr / day in worst winter months. You therefore need to put roughly the same into the house. You only need to input the net top-up, because your occupancy, normal electrical consumption and solar gains all contribute to this input; this net is going to be 1kW or less on average. Given that a cheap and simple Willis heater can provide 3× this, using something like a gas boiler capable of 16-20 kW is just crazy, in my view; in our case even the economic case for considering an ASHP is marginal at best. Yes, in terms of running costs, the electricity unit cost per kW is more than that for gas, but you also have to factor in other running costs such as boiler maintenance. In our case, the British Gas boiler maintenance contract in our old house is less than our total expected heating cost in the new house so unit price comparisons are irrelevant to us. As I commented in the Boffin's thread, you need to limit the heating going into the slab: one way (the one Jeremy currently uses) is to throttle back the heating rate right back (e.g. using a buffer tank and an accurate thermostatic blender) ; the other way is to use a chunking approach and simply heat the slab in one (or possibly two) chunks per day. In the chunking case you instead limit the total heat injected into the slab per heating round (that is the integral of the power rather than the power itself). Doing this might seem awfully complicated, but in practice you can let the slab physics do this maths for you. You can use any moderate heating source that has a reasonably consistent but limited heat output; this could be an inline heater like a Willis heater or an ASHP with the flow temperature and rate at present set-point giving water at, say, 30°C. The slab itself slab acts as the buffer, so no additional buffer tank is needed. The algorithm is simple: Turn on the heating at a fixed time. This could be the start of E7 or in the window of peak power if you have PV installed. Turn it off when the average return temperature from slab reaches a specific set-point threshold. The actual set-point (which in my house is going be around 27°C in winter) does vary by season because what you are doing is control the total heat put into the slab, and it will need trimming for any specific house and heating scenario, but it is largely self correcting for short term temperature variations in that if the house gets a little colder due to greater heat loses in a cold snap, then the slab will require more heat to reach the set point. At the moment we are using a twice a day heating cycle. This is settling down to ~6 hrs overnight during the E7 window about £1.50 and a couple of hours top up during the day (another £1). This being said, we are still warming the house from a pre-commissioning temperature of around 13°C to a pre move-in target of 20°C as as you can see from the graph, we are currently increasing the house temperature by ~0.5°C / day on top of the sustain heat losses. This in itself takes a lot of energy as we have approximately 17 tonnes of slab, 5 tonnes of plasterboard, 11 tones of wood inside the heated zone of the house and 8½ tonnes of cellulosic filler in the insulation. Plugging these numbers and their Cp's, it takes roughly 25 KWhr to raise this fabric by 1°C, or 4 hrs of Willis Heater to raise it by ½°C. So at the moment roughly half of the heat input is maintaining heat loses and the other half is slowly raising the temperature of the house fabric . This maintenance heating element is less than the JSH spreadsheet estimated for current average outside temperatures. So another way of thinking about this is that if we do without heating for a day, then the house will drop in temperature roughly ½°C to compensate for heat losses. The daily ripple in temperature with a single heating chunk will be less than this. If we only heat the slab during the E7 time window, say from 2 - 7AM, then the house temperature will peak roughly 3-4 hours later late morning and then fall by maybe ½°C during the rest of the day. I feel that a ripple of ½°C will be barely noticeable to the occupants, and given that the heating during the E7 window is effectively half price, it is better to accept a midday peak (and possibly set the target temperature half a degree higher) than to pay double for an afternoon heating top-up to reduce the ripple.

I thought that was you.

On the specific oxygen permeable /barrier point, Hep2O sell two types of pipe one slightly cheaper than he other. The more expensive barrier pipe must be used for CH applications for the reason that Peter explained, and can be used for potable water; the other can only be used for potable water, but is perfectly fine for that use.

I still don't understand the issue. How do you control the ingress of moisture above the lintels? In our case the lintels extend ~150mm beyond the end of the frame and we have a secondary DPC and weep vents above each lintel so this forms an "umbrella" over both the windows and gap closers. In principle you could still get some moisture ingress along the mortar stop between the brickwork and the window, but (i) this is sealed with a flexible sealer bead anyway and (ii) the preferential path is straight down. Though, in our case we fitted the windows into the frame on the last day of the frame erection and subsequently put the skin up to the frame which made things a lot easier. In terms of the gap closer, the one we used was mineral wool in a heavy duty PVC sleeve so there isn't any entrance path for trickling water. They were exposed to the elements for about six months and didn't show any signs of getting wet, so I doubt that we'd have any problems once protected by the skin. We can have chat on Thursday.

The inner frame and the outer skin have different material and thermal characteristics so you will always get some form of shear movement between them, even if the odd mm. If you mount your windows in the brick then this will always end up compromising the airtightness of the build. If you mount the windows in the frame, immediately behind the brickwork then this shear line is at your outer weatherproofing mastic seal. I don't understand your point about the PUR being close to the cavity tray. You have to do this for two story buildings or higher to form a proper fire stop (remember Grendfell tower). I realise that it might be a bit late for you to do this but if you are mounting the windows forward, then putting a 60° angle on your inner reveals makes a huge difference in terms of light and impression. This opens the windows form the inside and make them feel far less like a tunnel. We've done this (and I've posted some pics to the forum too) and visitors to the house often comment on them --- always favourably. See this for more details:

A bit late, but the other alternative is to mount your windows 50mm forward and surround them with PUR or mineral wool gap closers to act as side insulation. That way you'll only have a pointing gap between the windows and the brickwork. If you use PUR then you might need to do a little surgery to allow them to slip over your edge wall tiles, but modern triple glazed window cassettes are reasonably deep. You can hang the windows on decent steel straps, but just make sure that you foam up properly; cut the excess of and silicon up the cut surface and face with decent airtightness tape.