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Just wanted to post a little update incase anyone else finds this and is thinking of it. It worked rather well. We've injected just under 10m3 into the cavities of the house, and it's already a lot more comfortable. I think probably what was worse than the lack of wall insulation was that the air bricks were not funnelled into the sub floor - it looks like some time in the past the floor has been replaced (i'm guessing it was circa the 80's) and all they simply knocked a hole through the inner skin into the subfloor, but the air bricks were letting freezing cold air all through the cavity. We installed 100mm pipes and foamed around the the inner skin to seal it up (to stop the EPS beads going under the floor), then mortar and (eventually) some vents over the exterior skinny to tidy it up. I've gone for closable vents on the outside so we can block off cold air to the sub floor during the freezing months. You can actually walk on the floor now and be comfortable - obviously yes there is a concern with rot of the timber, so i'll open them occasionally to air the sub floor out. The machine itself I made up in a couple of hours out of a piece of mdf base, an old compost bin i had laying around, and the £50 3kw leaf blower from Screwfix. I also made a PVA glue hopper out of an old pump and bits i had spare also. We watered down the PVA 3 to 1 and injected this near the nozzle so it coated the balls on the way through. Initially we were removing bricks as our nozzle was 50mm, any smaller and the machine would clog up. However i realised that if we blocked off the leaf blower inlet to 20mm, we could have a 20mm outlet and it worked perfectly, just a bit slower. So we did that, and used a short bit of 22mm copper pipe as our nozzle to inject through. However it meant we could drill 25mm holes with an SDS bit - much nicer than removing bricks. The main hose was a standard 100mm duct. The eps beads flew in with some serious pressure - worked great. We did have a little issue in the cavity wall not being closed in a small loft space above the utility room - bit of PIR and foam took care of that. I did take half a day having to get the beads back in the bags however to go again, however I did have to laugh when i popped my head through the loft hatch to see a giant pile of beads not where they were supposed to be. The jury is still out on the PVA - difficult to know if the mix was right, and if it was being pumped in quick enough to make any real difference. All in all, total cost of £500 for some beads and £100 on materials. £50 of which is the leaf blower which is fully useable again to actually blow leaves... I do plan to suck it back out the walls and re-use it whenever we come to demolish the house in the near future, save the landfill and a few quid!

I live in hope! I design a lot of slappings in walls, to make open plan houses and so on. To do this I need to open up parts of the walls and ceilings to see where the joists run and so on. Used to be great in the old days when folk had just carpets, now there are tiles and all sorts so you can't lift floors above so easily. For all on BH.. on modern homes you find that with engineered joists and so they run in all directions and the services can be a bit bizarre, also in modern homes there are a lot more "services" .. and there is no real coordination... what is hidden in your floor depth is a lottery for someone investigating it. Also used to be great when sparks did a proper job.. ie running their cables mid depth of the joists (they know they should) with a small sag so clear of the ceiling. Got caught a few months back. Used to use an insulated plasterboard saw and sometimes don't turn off the all power.. then started using a multi tool.. makes a professional looking cut when doing a structural investigation but once the hole was open here the spark had left a coil of cable lying on the ceiling..the socket ring main. I nicked the cable. The multi tools are great but you have no feeling.. if using a hand saw you sometime get a feeling.. like driving an electric car cf an Astra van. Now it's out to the van and get my "near disaster avoided kit" to sort it as a temporary measure. I also keep in the van.. a distaster kit.. yet to be used.. luckily! Here is a thing for all on BH.. I'm an SE and you may be wondering.. what is Gus doing? I'm just being practical and trying to get a handle on how the building works and where some the booby traps lie for the builder that will have to implement my design. I could pass on all the risk to the Client but it's about getting a balance. If you don't take a bit of a risk when opening up old buildings you are designing on complete guess work and that generally ends up in tears. Yes I nicked the cable but I always explain to the Client before I start.. the more we explore now the better information we can give to the builders and this protects you. When I nicked the cable they were fine about it. It would be great to find a tool that has xray specs! Can it find cables, pipes and studs?

Displaced, not saved.

Hi @Sparrowhawk The below is my overview. Whilst I know you are going for a new boiler, the process below would still be the same. You will save a lot more over time fixing airtightness, the insulation and installing mechanical ventilation. Triple glazing is the most expensive element to install per m2 with the least energy saving(although important when everything else is high spec). Get yourself a heat loss calculator ( I use an excel spreadsheet for this ) and play with the elements and you can work out what gives you the best money spent/ money paid. Normal double glazing with a U-value of 1.2 versus your triple glazing say high spec 0.6 U-Value. Inside temp 20 centigrade, outside temp zero C will give a saving of about 10.6Watts per square meter. (ignoring any non air tight issues with the old double glazing window installation or the rest of the building) Aim to go APE It worth considering all the AIM and APE elements before making decisions. That is Airtightness, Insulation, Mechanical Ventilation with Heat Recovery OR Heat pump Ventilation, and Air Source Heat Pump, Photovoltaics and Electric Vehicle. Some of these will not work properly without the others, and some will complement others: A MVHR will not work properly without Airtightness. An Air Source Heat Pump will have to compensate for the lack of Airtightness and/or Insulation to the degree that the benefits become questionable, especially during winter, without them. An ASHP uses electricity and Photovoltaics can supply a little during winter and a lot during summer when cooling can be a problem and an ASHP can supply cooling. PV can supply a little to an Electric Vehicle during winter and plenty during summer if your vehicle is at home during sunny days. Extending a property and only doing AIM works to the extension will be no good, you have to do all the property within the thermal envelope. And thinking of running costs: a) Airtightness and Insulation should have no running costs and last (Well, loft insulation lasts over 40 years, in our experience) with the exception of UPVC units for windows and doors, but that being said it will last 30 years? b) Our MVHR unit servicing 100m2 floor sized home uses about 260kWh a year; far far less than would be used to heat incoming cold fresh air in winter, and we clean the filters twice a year. c) ASHPs are, in my opinion, still in their infancy but we are now in the second year of use here. We were very careful to follow best practice in the design and installation of our system, did a lot of bespoke tweaking, and we now have an upgraded 1970’s timber framed bungalow that uses less than 25kWh per year per m2 of floor for heating. d) PV would be a lot less attractive if there is no ASHP or EV (or battery backup) or diverter to the hot water immersion. In my humble opinion, if you have a suitable roof you should install as much a physically possible. Electricity production costs (cost per kWh) are difficult to evaluate because it depends how much is used and how much is supplied to the grid. We decided to go with the PV cost divided by 7 years, which for us works out at £1.60ish per day. Yesterday the PV produced 12kWh all of which we used. Remember, 5kW of PV panels will not produce 5kW because you would have to have: i. No shadowing of any of the panels during sunlight hours (like trees, buildings or chimneys. ii. All the solar panels face exactly the right angle in relation to the summer solstice midday sun for their position on the planet. (Perfect angle facing south and perfect slope) iii. solar panels completely clean iv. the sun is completely unobscured v. the Inverter is 100% efficient vi. all the other losses due to cables, and equipment, and so on. e) Knowing the above PV limitations professional installers often add extra panels to make up for these losses. (Our inverter allows us to add roughly 28% more panels than its kW rating) f) PV panel installations will produce about one fifth of the power in the winter compared with what is produced in the height of summer. g) The electric vehicle and charging from the PV only really works if you can have the vehicle plugged in during the day and supply over 3kW from your PV (or a large proportion of that). This is why we went for the biggest PV that would fit on the roof. We then installed a system which only charges the when the PV is on and generating over 2kW in winter and 3kW in summer. (we have a 13amp charging system). So, if finances cause you to have to consider only a few in my humble opinion AIM first and go APE later. (But prepare the property for the APE works as much as you can). Best of Luck Marvin

It will as you will get a much more efficient boiler today - we did the sums here and came down to a modern 27kW boiler from a 32kW 30 year old one and still we use a lot less gas than before.

But a standard dumb immersion heater learns demands too- when hot water is used, its replaced with cold water and the thermostat activates and heats water via element. I fail to understand the obsession with apps for every day items.

I’d like to offer help to anyone who needs help doing drawings or designing their home or extension. I'm a Registered Architect with some time on my hands. I use my iPad and an app called Concepts to draw and have already helped out a few Forum members.

Yes. We used plastic fibres and the slab was 100mm I think. It was laid by the family who had no preconceived bias. So the fibres added about £10/m3 to the concrete, and saved all the steel. Labourwise the concrete is a bit stiffer and added 30 minutes, but was countered by much easier access without mesh to cross. And no mesh labour. Normally we would slice crack control next day but for somd reason ig wasnt done. But there are no cracks anyway. The junior SE was reluctant but the senior one stepped in to say it was ok. This was not a normal discussion though, as we are as qualified as their senior guy. To summarise, we laid sub-base, dpm, 100 concrete, 125 pir, more dpm, 60 poured screed. The latter was by professionals. When concreting do not add water to the mix.

Yes That's what I mean by "a sunset of loads".

No ! I tried all of them - complete shite . Did a thread on it ; can’t be bothered to link edit : Used the (expletive deleted)ing search function

Spot on. Please be careful here. Like all things TF takes a bit of learning about. Structural stuff: First thing is building stability. With TF you get about a 25% contribution from the external leaf of masonry, no masonry.. debatable contribution from the outer skin. Next is insulated plasterboard on the inside. If normal plasterboard straight onto the studs you get a contribution (last resort when stuck on the sums) from that provided you are sure it is not going to get wet. Insulated plaster board.. no as the fixings tend to bend in the insulation. You have openings.. these can drastically reduce the racking resistance and if large bifold doors ect these can completely change the way the forces act.. often you need to check that the existing building can cope with the extra sideways load and pulling / tension effect it has on the existing house walls. Depending on where you have the openings a tall narrow TF panel can generate significant uplift at the bottom.. so you need to check the tie down strap nails and make sure you have enough ballast in the underbuilding to resist the tension in the straps generated by the over turning effects in the panels. Turning now to the vertical loads the studs need to carry. You can put a surpising amount of load down a TF stud when is is prevented from moving along the plane of the wall, its minor / weak axis as the OSB restrains it. But when you couple this vertical load with a wind load it has a reduced capacity.. quite a lot. You need to check the case of wind pressure bearing down on a pitched roof coupled with the weight of the roof.. often it is okunless you live in a windy spot and the roof is not flat. But if the stud length is over 2.4m in height this can suddenly becomes and issue as the TF is holding the external skin. Last but not least.. you need to look at your windows and doors.. how much defection can they cope with both vertically and horizontally. Some detailing stuff: Make sure you get your cladding details sorted. You may want to put a chamfer on any horizontal battens to channel water to the cavity where it can be properly dealt with... it's these apparent minor details that matter a lot for a durable build. Have you checked to make sure you don't have a fire boundary condition? Make sure you get the cladding ventilation and insect grills nutted out both top and bottom, soffit details and so on. Make sure you get your fire stops right and that there are corresponding studs behind. Have you decided on how you are going to do the corners of the kit (California.. don't like them structurally) how you are going to insulate and the sequence of work to be able to do it. Yes but this may be a good opportunity and avoid a howler.. why do all this work and risk that when you come to sell someone asks.. is that ok and can you prove it? The above sounds like a bit of a rant from me but you have a great opportunity here to learn loads and practice on your own house. I started out a while ago.. bought my first flat and learnt how to get started on the practical side of the building trade and earn a living. In summary if you want post some plans and elevations (rough dimesioned sketches will do as you are not tested on your drawing skills on BH) of what you propose and plenty folk on BH will chip in with advice and tips. It may be that you will conclude that it is your best interests to pay for some SE type advice.. but .. do a good job.. let the SE see you can and they may put you on their list of "good guys" and work will flow your way to boot!

What did your architect draw? I altered our driveway design slightly (Conservation Area, planning condition) from bonded gravel to gravel and some setts and pavers, by adapting the architects drawing and then tracing it by hand onto watercolour paper, which is textured and has heft. I then annotated and drew the lines in a nice thin black Sharpie and coloured it in vaguely with a kids cheap watercolour paint set, with lots of shaded green, and the gravel slightly brown. I also mentioned native hedging blending with local landscape, and got amenity and biodiversity in there too. I didn’t show obvious flower beds. Not sure what my architect would have charged, but it cost about £10 to do. My point is, I made it look arty, like I cared (which I do). BTW it’s worth submitting your planning conditions together as much as possible, as you only pay per submission, not per condition. And sometimes it turns out you don’t even need to discharge them at all, but you might have to ask/wait to see if you get dobbed in. Strictness possibly varies between councils.

Here you are . Bosch , natch - wodja expect from me? Bought mine years ago, works well, gets nicked often by the children. Love the central hole in which to shove a marker pen so you can accurately mark the wall.

For example. The tape I'm on about, colloquially called "compriband", whatever the make, expands massively to fill the gap. You can get it adhesive one side that you stick to the window frame JUST before it goes in. Or tape you push in afterwards.

fr = Fr/N

Your initial separating tank is using a vortex so this may not be relevant but the common way to design the inlet pipe going into a tank is it extend vertically down to near the bottom of the tank and terminate with a U-bend, forming a so-called 'calmed inlet'. This causes less stirring up and keeps the top surface layer, where bacteria and floaty things you don't want congregate most, as well as the bottom sediment from being disturbed.

That's twice my whole house heat requirement at minus 3 centigrade outside and plus 23 inside. Eight times the loss per m2 floor area of mine. (104m2) Something needs seriously fixing!

Just looked at my SAP report and for a house with a 7 ACH @50pa, the actual infiltration rate is 0.4217. So I would lower the ACH down to 0.5, instead of 1.5. that should lower your losses quite a bit. At the moment your lounge heat loss is 25% higher than my whole house, so doesn't look right.

About why you need a buffer tank?

I have two types of paver out in the back garden - some kind of rose-tinted, irregular sandstone-y stuff where the patio door is, and cheapest-possible concrete pavers along the rest of the house. You'd think the sandstone-y pavers would be better, but they allow water to pool much more, and that freezes into almost-invisible sheets of ice. The cheapo ones are much gripper by comparison. I pop https://www.yaktrax.co.uk/ on at the first hint of ice in the streets, so away from the house I barely even notice the grippiness of different surfaces. The only thing I have trouble on is metal - they bite very satisfyingly into everything else.

Last week I was impressed with my car tyres. I went to a job on one of the housing estates, knowing the estate roads never get gritted I went slowly, not the merest hint of traction problems or wheel spin. I got out of the car and nearly ended up on my aris, the road was that slippy it was hard to stand up.

Here too https://www.google.com/amp/s/www.cornwalllive.com/news/cornwall-news/st-austell-large-battery-storage-7899714.amp

That is the ultimate idea. Run the 'virtual' generator at fixed output and at best efficiency constantly. There may be better ways to do that than though variable pricing. If each house in this trial displaces say 0.5 kWh, that could easily be done with a very small battery system. Shift it up a layer, a larger battery at the local substation. There will be a point where the substation and recharge/discharge efficiency is optimal, and that should determine the best placement of a system. If course we could easily add in thermal storage, even if just a 50lt water pre heater, or even a cheap storage heater hanging in a wall. It is too easy to want the best system there can possibly be, rather than a cheap and easy one.

You can, just do it via a buffer tank or thermal store and a mixing valve. The boiler will still condense then.

The iCF blocks from Thermohouse used on my build are made from graphite eps beads. They have bolded in the electrical section of their installation manual the following. This short document https://electriciancourses4u.co.uk/useful-resources/what-effects-different-types-of-thermal-insulation-have-on-electrical-insulation/ Puts the onus on the insulation manufacturer, to check their products data sheet. Found this 2004 ministry of defence document advising against electrical cable with EPS. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/33549/spec34.pdf I pretty confident that 18th edition electrical regs will be consistent with these requirements. I believe BASF invented the graphite eps beads. They may have some details on this issue.

Assume those are dense concrete blocks, ergo no need for a padstone under the ends of the steel? If block on flat for those walls, where is the cavity or insulation to be placed? At the very least you'd expect to see those to have been made good with a brick and mortar infill? The drafts will be a bit of a problem if not dealt with prior to facias going on.

Sorry to hear your challenges, @GrantMcscott. There's been quite a bit of nodding to theory on this thread (which is important). FWIW, your floor spec is - to my eye - pretty good rather than reasonable. By ufh only has 90mm of PIR under it, but was built in 2009. Your 150mm will on its own meet the current building regs newbuild value of 0.13 in England, which was not pushed further in the latest update in June 2022, and looks to be here to stay. My suggestion is to get an inexpensive thermal camera, and take a pretty comprehensive set of photos outside and inside whilst it is cold out and and warm in, which will show heat leaks (including warm outward draughts) well. You should also see useful cold spots etc with photos taken inside. Once you have that data then you can decide what to do next. Simple tools you may also find useful are things like (sample sources): A £5-10 hand held point and shoot thermometer: https://cpc.farnell.com/duratool/d03308/infrared-thermometer/dp/IN08363 A couple of £10 or so min/max thermometer / hygrometer https://www.amazon.co.uk/Digital-Thermometer-Hygrometer-Temperature-Humidity/dp/B00VYRC58I/ It's he simplest form of data logger ! I always have a couple of these around for quick checks. Then you could have a simple datalogger recommended by one of the BH co-conspirators. My house is a little smaller than yours - 200sqm, but I live here on my own (with the squirrels and the foxes) and my energy bill in December is also going to spike. I've been running a couple of rads only (24x7 for some of it which I have just cracked down on), and closed down all the bedrooms except one. Are there any parts of yours you can seal off for the winter, to reduce the volume heated? I don't know about your wood supplies, but have you considered running your woodburner overnight in a damped down mode? One other thought - are you on an optimal electricity tariff for your heating strategy? What would happen if you switched to a cheap overnight tariff and ran the UFH heavily then, and relied on the slab-heat-delay plus wood burner to keep you warm in the day? ATB Ferdinand

Sorry you mentioned 1 year old so I made 2+2=5 and assumed you were looking at buying a second hand unit.

Yes poor install detail. the extract pipe must run straight and flat with a gentle fall to where it exits the building. I bet your fan sits in a dip with the pipe risong either side of it, a perfect "sump" for the condensation to form in.

Everything is connected to everything else and not many people are thinking through the 1st order consequences let alone the second and third order unintended ones. We need to get our head in order so as to steer a path through this lot.

No offense but you're sort of missing the point. Having passive (or better) levels of insulation and airtightness are what leads to very low energy bills. Do it to current building regs requirements and you're already on a loser. Every compromise is lost heat. As I always do I'll come back to Jeremy Harris's comment. Even with 300mm of EPS under his floor slab, 8% of his heat losses were through the floor. That's a continuous concrete slab with just a few service penetrations. There are then self builders on here who's houses aren't Passiv certified but have exceeded those specs.

This will be much better.

I feel for my new neighbours. Same basic house construction as mine, circa 1930. They've just re-roofed and ewi is yet to be done. In fact their planning application waxed on about the refurb resulting in a "thermal envelope". The external finish and attention to detail looks brilliant and they've had new windows. Not sure if they're 3G but they still appear to be in the outer leaf (it could tbh be solid brick with no cavity). The place was suspended timber floors, I don't know what they've done there. The work was done by their extended family who are builders. The thing is they have an ASHP fitted before things shot up. I'm wondering how they're fairing now. Hoping for a tour sometime. I watched their application proceed and on the basis of it am seeing the same local architect tomorrow hopefully.

What sort of flexi pipe is it? The thin single-walled white stuff? If so, insulated flexi pipe is far better and it's also a lot smoother internally resulting in better airflow.

If you want the original company to pay to fix it you may have to give them "opportunity to rectify". Otherwise if it went to court they could claim they offered to fix it but you didn't let them. You might have to prove they didn't have the expertise using expert witnesses. If its not a huge amount of money I would get another company in. However this time have them explain to you (ideally in writing) what the work involves so you can check it meets your expectations before they start.

I know that feeling. It depends on your capacity for stress, the amounts involved and your financial situation. If it's not a very big deal, I've tended to just sort things out and have no further dealings with the company. If it is really bad or there are other indirect implications in their work, you might want to go the legal route, but it's not for the faint hearted. Can you post pictures and explain the problem? There are very experienced people on here who would guide you to the best course of action. I've learnt about housebuilding in a back to front way, by looking at stuff and thinking 'That doesn't look right', and then gone off to research on here to confirm or allay my fears.

It is a common enough conundrum and I am sorry you have it. Perhaps you could tell us a little more. What was it that you think was done incorrectly and how do you know it was done incorrectly IE are there any obvious consequences? How did you pay for the work cash, bank transfer or credit card? Each of this carries a little more information and in the case of the credit card some protection.

I believe merchants are going to have a think long and hard about any price increases in 2023. Demand from both domestic and commercial builders will be a fraction of the levels of recent years. Any material buyer in '23 will certainly find good value if they look for it.

It sounds as if you have all the strength you need, and the tarmac is only for tidiness and smoothness. So the tarmac can be much thinner. 100m x 3?= 300m2 × 150mm = 45m3 X 2tonnes x £100(?) £9,000 for the material. You should at least half that and also save on sundries and labour.

Only thing come into my head after reading lots of threads. Above 16A so 3.6 kWp you move from G98 (tell DNO after install), to G99 ask DNO for permission before connection. Depend on where the batteries are in the system DC part or AC after you PV inverter, this either increases or doesn't change the kW you could export. Export potential is the measurement the DNO are interested in, not that you do or don't want to export.

Well, just round the corner from you (Lancashire) , I'm hearing that customers are pulling the plug on building projects if they have arranged finance recently on a variable rate. A good chippy near us is talking about the end of next year before he can come: and no drop off in sight. Another local builder was glad to be able to come and work for us replacing the chimney on our cottage as soon as the weather improves next Spring. Currently the picture is variable, but the trend is worsening. All of this is word-of-mouth: to be taken with a pinch of salt, therefore.

I think there are mixed results for different trades in different areas of the country... Its honest of them to let you know and not keep you hanging. They may be a big company that is involved in large contract works, although I don't think HS2 is going that far!!! Try some others. I would try the Asphalt batching plants for company names. They will know who is working in your area. Good luck M

Having been in the tree business for 30 odd years, I would go for a walk around your local area and look at what sits naturally around there. Get a good tree id book and see what would fit in with the task you need it to perform. Tall and thin to hide a telegraph pole. Big and spreading to block out the nosey neighbour. What is good for wildlife, don’t forget hedges, you get far more living in a hedge than most trees. Try and stick to indigenous, and if you plant any conifers for hedging stick to western red cedar. If you plant any leylandii you need a swift kick in the gonads.

This is how I work with this type of system. I run more of the counter ( service ) battens horizontally, so they can be fixed side on thus not needing to fix through the membrane, and then the boxes get drilled and screwed up and down into the horizontal timbers. The Egger board was installed to take the wall mounted TV’s, so they could be fitted with the correct depth / length screws so again the membrane didn’t suffer damage from any such retrospectively installed equipment. Injecting 330 foam all round the Egger board would offer further insurance. The sparky should drop down and go through to the next room in the joist void imo, or create a penetration with a conduit which can be filled with Illbruck 330 foam and made airtight accordingly. As said, you must lead on this, as most trades still have little to no experience with airtightness disciplines / products etc, and you should be prepared to provide them with the correct foam / tape etc if you want this doing correctly.

We let our 1 acre paddock go wild at the last house. We cut lawn tractor wide paths through it with hidden seating areas. It was great and we used it more than the garden.

Just stop mowing it. Mind you, you'll need nerves of steel just to "let it grow", blinds will be twitching, and parish councils will be tutting. We did this and the number of flowers that came through was remarkable. Nothing spectacular, just clovers, buttercups, dandelions, daisys, trifoils etc. Despite the non exotic mix the bees and the butterflies were very much appreciative. For some added child fun you could lawnmower a series of paths through it.

We moved into our new build mid-December 2017 in time to host an extended family Christmas. We are now over 4 years into living in our new home. We have lots of accumulated experience and made a few small tweaks. However, we are delighted about how the house has turned out, and we love living here. There were no material cock-ups, or regrets on design decisions, so we have probably fared a lot better than most new purchasers or self-builders. Maybe a general experiences post should be on the to do list, but what I want to focus on here, and a couple of follow-ups, is a general topic that others on the forum have asked about over the years: that is how our central heating system works in practice, and how I control it. The system as currently implemented is still largely the same as when I first commissioned it, that is a now 5 year-old RPi-based custom control system directly controlling the CH and DHW subsystems. This is a pretty minimal headless system running Node-RED, MySQL and MQTT client for control. The three material changes that I've made since moving in are: I have followed my son and son-in-law in using Home Assistant (HA) for general Home Automation. My server (an RPi4 in an Argon One case) uses an attached Zigbee gateway, and I have a lot of Zigbee devices around the house: switches, relays, light sensors, etc. and I do the typical home automation stuff with these. There are loads of YouTube videos and web articles covering how to implement HA, so please refer to these if you want to learn more. My HA installation includes an MQTT service for use as a connection hub for these IoT devices. I also have another RPi4 acting as an Internet-connected portal / Wireguard gateway/ file-server for caching video snippets from my PoE security cameras. Note that none of my IoT devices directly access the internet, and the only in-bound access into my LAN is via Wireguard tunnelled VPN, and my HTTPS-only blog. All other ports are blocked at the router. Before moving in, we assumed a target internal temperature of 20°C. In practice, we have found this too cold for our (fairly inactive OAP) preference and so we have settled on a minimum control threshold of 22.3°C. As you will see below, because we largely heat during the E7 off-peak window the actual room temperatures have a ~1°C cycle over the day, so the average temperature is about 22.8°C. This hike of 2.8°C increases the number of net heating days since my design heating calcs and the increased delta against external temperatures in turn increases our forecast heating requirement by roughly 18% over our initial 2017 heating estimate. Because our UFH is only in the ground-floor slab, we found that our upper floors were typically 1-2°C cooler than the ground floor in the winter months. We also need more than the 7 off-peak hours of heating in the coldest months, so I have added an electric oil-filled radiator on our 1st-floor landing; HA controls this through a Zigbee smart plug that also reports back on actual energy drawn during the on-time. HA uses MQTT to pass the actual daily energy draw back to the CH control system. This radiator provides enough upper-floor top-up heat, and does so using cheap rate electricity. Note that all servers are directly connected to my Ethernet switch, and the CH/DHW system has all of its critical sensors and output controls directly attached. It can continue to control the CH and DHW subsystems even if the HA system or Internet is offline. There is also no direct user interface to the system, with all logging data is exported to MQTT, and key CH/CHW set-points and configuration are imported likewise. This integration with MQTT, enables user interfacing to be done through the HA Lovelace interface. If there is sufficient interest I can do follow-up posts on some more of the "Boffins Corner" type details on these implementations, or if this turns out to be more of a discussion then it might be better to move this stuff to its own BC topic. However, for the rest of this post I want to focus on the algorithmic and control aspects of the heating system. In terms of inputs and outputs to the control system, these are: There are ~20 DS18B20 1-Wire attached digital thermometers used to instrument pretty much all aspects of the CH / DHW systems. Few are actively used in the control algorithms but were rather added for initial commission, design verification and health checking. Some are also used to monitor and to trip alarms; for example, there is a temperature sensor on the out and return feed for each UFH pipe loop. These were used to do the initial zone balancing. However, the average of the return feeds is used as a good estimate of the aggregate slab temperature. One of the temperature sensors is also embedded in the central hall stud wall to act as a measure of average internal house temperature. There are two flow sensors on the cold feed to my 2 SunAmp DHW storage units to monitor DHW use and to help automate during-day DHW boost. There are 4 240V/20A SSRs used to switch the power to my (2-off) SunAmps, my (1-off) Willis heater, and my (1-off) circulation pump. These and the rest of my 240V household system were wired up and Part P certified by my electrician. These SSRs are switched by a 5V 50mA digital input, and so can be driven from an RPi or similar. (I used a I²C attached MCP23008A multi-port driver to do this, as this can drive 5V 50mA digital inputs, but its input I²C side is compatible with RPi GPIO specs.) There are many ways to "skin this cat", but whichever you choose for your control implementation your system will need to control some 240V/12A devices and take some input temperature sensors. My preference was to directly attach all such critical sensors and outputs. My heating algorithm calculates a daily heating budget in kWh (each midnight) as a simple linear function of the delta between average local forecast temperature for the next 24 hrs and the average hall temperature for the previous 24 hrs. This budget is then adjusted by the following to give an overall daily target which is converted in minutes of Willis on time. heat input from the heater mentioned above. a simple linear function of the delta average hall temperature and the target set-point (currently 22.3°C). This is a feedback term to compensate for systematic over or under heating. I initially calculated the 4 coefficients of the two functions using my design heating calcs and an estimate of the thermal capacity of the interior house fabric within the warm space. After collecting the first year's actual day, I then did a regression fit based on logged actual data to replace the design estimates by empirical values. This was about a 10% adjustment, but to be quite honest the initial values gave quite stable control because of the feedback compensation. The control system runs in one of three modes: No heating is required. Up to 420 mins of heating is required. The start time is set so that heating ends at 7 AM, and the slab is continuously heated during this window. More than 420 mins of heating is required. 420 mins of heating is carried out in the off-peak window. On each hour from 8 AM to 10 PM, if the hall temperature is below the set-point (22.3°C), then an N-minute heating boost is applied, where N is calculated by dividing the surplus heating into the 1-hour heating slots remaining. Here are two history outputs from HA showing some of the logged results. The LH graph is the slab temperature over the last 7 days. The general saw-tooth is identical from my 3-D heat flow modelling discussed in my earlier topic, Modelling the "Chunk" Heating of a Passive Slab. The 7 hr off-peak heating raises overall slab temperature by ~4-5 °C; well within UFH design tolerances, and no need for any HW buffer tank: the slab is the buffer. The RH graph is the hall temperature. Note the days where on-hour boosts were needed. (Also note that the CH system only updates the MQTT temperature data half-hourly, hence the stepped curves.) So the approach is fairly simple, and the system works robustly. ? And here is a screenshot of my HA summary interface, which gives Jan the ability to control everything she needs from her mobile phone or tablet.

@Jenki IMO, implicit to all this is that I have a passive class house in terms of U-values, air tightness, MVHR, etc. In this, inter-room or inter-zone heat transfer is an order of magnitude higher that interior to exterior transfer. I have what is called a warm slab -- that is the entire reinforced floor slab is within the insulated perimeter so my total thermal mass internal to the external insulation barrier (I did the sums once and reported these on a post somewhere) IIRC is equivalent to that of ~100 tonnes of concrete. If the heating fails, then the house as a whole cools at around 1°C per day. In my previous house we heated by room, with only a few rooms kept at a comfortable temperature. In our current house every room and touchable surface is essentially at the same temperature within a degree or so; zones make no sense in this new context. Our UFH, loops were laid into the slab by being tied to the rebar before pour. The layout avoided walls etc, but MBC advised that we keep the loops all the same length (and close to the 100m roll length). We could have just about fitted in 4 × 100 loops, but this was tight. As I only needed to pump a few kW into the entire floor, we spaced the runs out a little and dropped heating the utility room, so that we could make do with 3 loops (which when laid actually varied from 93 – 100m, IIRC). I trimmed the manifold valves by setting them to max and slightly closing them as need so that the temperature drop across all three zones when heating was the same. The Willis actually draws 2.88 kW, so an entire 7 hour heating budget works out at just over 20 kWh. 2 × Willis seemed like overkill at the time, as a single unit should have been enough to keep within cheap rate for maybe 95% of the year with our planned 20°C target, given our expected other waste heat. However as I said previously, we upped the heating set point for comfort ending up with an average some 2.8°C higher. BTW, pretty much all electricity used within the house ultimately cascades down a waste heat within the environment. In practice our new lighting, computers, and our other base electric load ended up being quite a bit more energy efficient in the new house, so this waste heat element was less than anticipated from previous use. The electric rad on the landing typically adds 8 kWh over night for a full 7 hour window. We have maybe 30 days a year where we need to top up over this 28kWh threshold, and end up using peak rate electricity. So yes, using a bigger resistive heater such as a 5kW inline or just 2 × Willis (as others have done) could have kept heating in the cheap rate window, but it just wasn't worth the hassle to make this change, as our current arrangement only adds maybe £10 - 15 to our annual electricity bill.

Me to. And the service can be cancelled at any time. With stored energy, reducing parasitic losses is the name of the game. I just boxed in my cylinder with Celotex sheets and mineral wool. Cheap and easy.