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MVHR doesn't have anything like the airflow needed to provide serious cooling. Design in air conditioning (completely separate from the MVHR), and throw on some PV so you can run it for free on hot days. MVHR will help keep the heat outside.

my 2 cents..... 1. external blinds are a must. plan them now so they can be built hidden in to the fabric of the house. we use ours to shade from the sun but also as curtains at night so don't have internal curtains for privacy. 2. just install AC when i was researching i read a lot on here about fan coils and underfloor cooling etc and, in the end, it was just too complicated for me. not being able to heat water and cool the house at the same time just seemed a pain. so we planned for and installed ducted AC in the bedrooms and wall mounted units downstairs in a few rooms that we thought would need it. it is fabulous. the external blinds help and we have them automated to shade and follow the sun around but sometimes you just want to open them up fully and enjoy the view! so the AC takes care of the overheating and it's powered by the sun via our solar pv so i don't worry about running costs at all. our south facing bedroom has been a steady 21°C since April regardless of the outside weather. keep it simple, install AC.

36C outside yesterday. The aquarea purring away at 16c (ramping up/down automatically to keep the right side of the wet bulb). walking into the ground floor is like walking into a fridge even theough its 21, the ufh loop does its work. The bedrooms though with the panasonic fan coils are sitting at 21 while the bathroom and landing are 26/8. CoP is reported as 27, although i guess its not setup for cooling ? Free anyway with the mega excess of solar. added the new 2025 model into the loft and also included the condensate drain, this is the largest unit they do and the heat exchanger is about 80cm wide so should be a beast for cooling.

We put our vat claim in a week ago Just over 43k They have just contacted me to ask me to check my figures as they get it to £60 more Requested 6 receipts Then will pay it Hernia op in two hours Then 3 weeks taking it easy Hopefully paid out by then

Well, sort of. Working physically hard is sooo emotionally easy compared to the frenetic whirlwind of strip foundation digging and filling. If that means that to you, I sound an emotional fruitbat then I commend your perceptivenes. I find it impossible to predict in advance the bits that will be most stressful. In the last two weeks I’ve had all but two days on my own on site, as Steve has been on his hols. So it’s background organisation tasks and planning for the most part. That means tip runs; getting blocks and bricks and sand and cement delivered for below damp; yet more manual moving of soil; generally tidying up; bumping out stupidly heavy 140mm concrete blocks; breaking up soft reds from the demolition for hardcore; and lots and lots of measuring and thinking. The two days Steve was there were spent setting out and getting some blocks laid. Setting out would have taken Steve on his own just a couple of hours. However, he had me to help him, so it took over half a day. I did learn a lot and because of concerns about preserving the precise sizes of the alleyways either side, and making sure the front face of the house is nicely co-planer with next door, and by the way still sitting properly on the foundations, and working out where to set block levels to, and my constant re measuring and questioning, I managed to burn a lot time more than just the morning. The levels thing was, in hindsight, quite comical. Not at the time however. We ran round the foundations with the laser level trying to spot the highest point, allowing for the 225mm steps. With the best will in the world foundations don’t end up perfectly level, so one finds the high spot, and all blockwork works to that level which saves stupid amounts of block cutting - adding more pug (perhaps a Suffolk word for mortar) is a lot easier than taking some off of a block. But with a laser level a higher number means a lower level, and one of the two of us just kept getting confused by that. I’ll let you guess which one. Confusion is, however, contagious it seems, as eventually I asked enough silly questions to get Steve confused too. It’s nice that I do have something to contribute to the process. Steve’s relief when he finally could get on with some blockwork was palpable. To his credit he must have been sorely tempted to insert the laser level staff somewhere painful, but he kept his patience, bless him. So we didn’t get that many blocks laid but we did enough to be ready for the windframe for the back of the house. Getting that fitted was fun. 200kg is not much by steel standards but my goodness it took some grunt. Because of the slope of the site instead of the legs (columns) being just over 2.5m long they were 3.5m long. The crew were a man short but I knew that when I asked them to come fit it so I gleefully volunteered to help. They were a brilliant pair - it was a constant stream of jokes and leg pulls and laughter. The only exception was getting each leg upright - that was pure grunt work - done nearly silently apart from grunts and barked orders. But the three of us got the first leg vertical. They then told me to ‘keep ‘old of that’ which turned out to be hard work, as keeping a near 12’ length of 1’ wide steel still on a blustery day wasn’t trivial. I also found it hard to believe that some goo squirted from a mastic gun would hold it up. I’ve read about but never seen a chemical anchor. Amazing. The other leg done we attached both legs to the previously lifted beam (with a genie lift - bloody handy that is) - and 16 bolts later we had a windframe. After weeks of a flat site it looks way too big, but after measuring many times I can now confidently confirm that I hope it’s right. Fingers crossed. The other thing this week is that the costs for the strip foundations are now all in, and we are quietly pleased. We were offered a fixed price of £16.5k, and lord knows what the extras would have really totalled as we did go deeper and use more concrete in many places due to soft ground. Instead, overall on day rate they cost us: Digger hire and diesel: £800 Labour (Steve and Kev the Dig) £4,400 Ply (some second hand) and cutting discs £700 47m3 of concrete £5,200. Waiting time for concrete lorry £74 Rebar (for steps and joins in foundations) £100 Spoil away £1,600 Total just under £13k. Happy days. It’s amazing what one doesn’t know and can’t imagine. When ordering concrete from the company we used (they only do 8m3 wagons) ordering 1+ means they send a full lorry then wait for us to tell them how much to send in the second lorry which turns up half an hour or so later. Ordering 2+ means two full wagons turn up at once - yikes! Ours site is just too small for that - hence the charge for waiting time. Anyway, next week Steve is back Wednesday so it’s blockwork to damp and over site over the next few weeks. And after a year of not doing anything towards my man cave at the bottom of the garden suddenly now I need to progress that too. It’s a nice problem to have.

All finished

Solar panels on - 10 minutes for two of us. From above From below Paint slats next and wire PV up

It definitely is a bumpy road, but the wife and I haven’t fallen out (yet) and we are seeing progress! All we can do is keep moving forward 😀

We had similar. I don't even know the make or type, the builder supplied them to the SE's specification. They pass over the top of the ridge beam as one piece and down to the rafters either side. They looked quite substantial metal not like most joist hangers.

I have said before, sell up and retire. Being a LL is not worth it these days. Let someone else have the "fun" of upgrading that to the required standard.

Your torque tighten, to ensure the bolt is stretched and is ideally mid way in the elastic range of the bolt or stud. This allows for changes of temperature, vibration etc and the bolt to maintain tightness of the assembly. If you under torque the bolt is not in the elastic range of the bolt material and if subjected to cyclic fatigue will give a very early failure of the bolt. It will break. If you over torque the bolt goes out of the electric range of the bolt and will stretch the bolt permanently, the bolt will yield. At this point you are applying almost no clamping force with the bolt. Your correct tightening torque changes due Bolt minimum dia Bolt coating Threads being lubricated Grade of bolt - 4.8, 8.8, 10.9 etc So you have dissimilar materials, aluminium and steel. You hot dip galvanise the steel structure, but be aware a strong galvanic corrosion can occur especially when wet between aluminium and zinc (galvanizing). If the top of the screw piles are steel no issue, if they are aluminium - ideally you need an insulated bolt kit, this will sleeve the flange holes and below washers, the flanges would need to have gaskets as well.

Was the title meant to be *pipe* clips and zip ties? I had assumed not and was waiting for an exposition on the myriad alternative uses for paper clips (apart from temp. replacement clips on split-link chains and repairing my reading glasses).

I'm no structural engineer but it looks fine to me. Taking that much out of the middle of the stringer would be a different matter As it's turned into share a picture of your home made stairs these are mine and are made of maple and cherry built around a central steel box

We had quotes for norrsken and kloeber as well as from our local aluminium window supplier who is a Smart Systems manufacturer. We are going with the latter, full measure, supply and fit. The cost was about 25 to 30% lower BUT the decision was based on the facts that 1. They are local with a good reputation 2. The can deliver the u value we "need" and all of the window door options we want in the same range (alitherm 400) 3. Both other quotes "bent" the truth ..." building regs say you must have 3G", " you can't have an outward opening front door and comply with pas 24", and both changed the size of at least 1 window opening to suit their range without mentioning it (double chk what the quote says) 4. Our suppliers order in the profile, spray to the ral colour we want, THEN measure the actual holes and manufacture in about 5 weeks, the others had timescales that meant windows would need to be surveyed off plan or would have a 10 to 14 week lead time. Our decision was also helped by the fact we actively did not want a wood finish inside and if necessary fitting could be done in more than one stage. Time will tell if we made the right decision.

Bro I made these 👊🏻

Thank you the op went well I’m home and up on my feet

Doesn’t the whole installation look a bit shit.

A relatively quiet week this week - the lull before the storm (hopefully not literally!) The scaffolders arrived to put up a single-lift all around the exterior on Thursday and Friday (and Saturday morning as it turned out). I say single-lift but there were due to be a couple of hop-ups for the gables on the south-facing roof. However, at one end the gable is over a canopy roof which means the first lift is 2m away from where the gable will be. We've left that one off for now - I'm hoping the timber frame company (Turners) can work off the scaffold tower at that end, or I will get the scaffolders back and put in what the frame erectors would like (we may need a sky-hook to hang it off though). The site is looking spick and span at the moment; the groundworkers were really tidy, the weather has no doubt helped (dust is easier to sweep up than mud), and Mrs P. has done some sterling work this weekend tidying up the few bits of spare timber, pallets, bulk bags etc, left by the scaffolders. As they were packing up one of the scaffolders saw an empty bag (which they had brought) and asked "Is this rubbish?", to which I replied "Oh yes, thanks", thinking he was going to take it away, but no, he just threw an empty Red Bull can in it 🤷‍♂️. Scaffolders truly are a breed apart. The house has proved to be too wide for the CCTV camera, so we moved the camera back. Now we have the workshop roof in the way - grrr! Looking at the project finances, frighteningly we have already spent over 1/3rd of the budget 😱. Major spend so far has been on design and planning, the timber frame and windows are both paid for, a good slug of the groundworks costs has also been paid with an invoice for the balance expected soon. This week I ordered and paid for the MVHR kit (based around a Zehnder Q350) and the ASHP and cylinder (Panasonic L series 7kW + 300l cylinder). I ordered the latter through Air2Heat who provide an MCS umbrella service (Paul Thorney - really helpful) so we should get back £7.5k via the BUS grant scheme, which would leave the heat pump and cylinder costing a net £1,200 plus installation costs. Anyway, we're currently running about £500 over budget (excluding contingency) with some opportunities for future savings and a fair few areas of potential overspend. Time for Benpointer's three Laws of Budget Management: If you go over budget, that's bad management. If you come in under budget, that's poor estimating. If you come in bang on budget, you've almost certainly committed both 1. and 2. Next week is going to be very exciting - I hope in a good way. Tomorrow (Monday) our timber frame arrives from Turner Timber Frames, with a team to erect it. The weather forecast is good, so fingers-crossed the frame fits the footings and it all goes up smoothly 🤞.

This is the thread I was thinking of with an excellent post from @HerbJ breaking down the MVHR numbers for another member.

Well it’s all back together and working, nothing has gone bang and nothing (apart from the Willis heaters!) is getting hot. I think I’ll chalk that up as a good result. ~~~ I’ll keep hold of these two in case the installer or his boss wants them.

We’ve just finished doing our vat claim I made a massive error when doing the build spreadsheets I wrongly assumed that the claim would have been as previously and would have to photocopy every recipe and send them off Well this time round no need for that BUT I didn’t add the vat numbers yo the spreadsheets So one full day and two evenings adding 650 vat numbers Lesson learned for next time 😁 (369k)My figures checker has just informed me that I’ve missed including legal lfees and CML Cert 3k FINAL TOTAL SPEND 372k Including fees and contributions 43k vat claim 420m2 over two floors Valuation 1.3 million Fingers crossed for the vat claim Just to add Ive carried a hernia for two years My wife blames the 7000 blocks I carried Ill get that sorted out next week So a month sunbathing for me 🌞

After a lot of research into UFH cooling with ASHP and Fan coils replacing radiators, this is the approach I'm going with. UFH with standard MVHR. Separate multi-split Aircon system to cool down the key rooms (bedrooms and living area). Heating things keep house nice, warm and relatively airtght. Cooling system blows nice cold air when I want it. Solar PV will mean you can run the air con on extremely hot days for very low costs.

We’ve had another very good week of progress by the groundworks team and they are pretty much done now bar some further levelling of the paddock area and one or two other minor details. We are really pleased with their work and the Building Inspector is pleased too, thankfully, so our foundations are all signed-off 👍. Bizarrely, it’s only now that we can submit the “Commencement Statement” for our construction to Building Control, which I duly did this week. Also bizarrely, we are still on schedule - I can guarantee that won’t last! Once the block and beam floor was in and grouted with cement slurry, the concrete block upstands for the internal stud partition walls were laid. With hindsight, it might have been better not to pay the timber frame company (Turner Timber Frame) to supply and erect the internal walls but rather build them later on top of the screed. But we’re way past that decision point now - Turners will be installing those partition walls as part of the overall frame build, so concrete block upstands have to be ready in place. One minor issue that had to be resolved this week - the block and beam floor ventilation ‘periscopes’ are designed for 100mm cavity walls and weren’t going to fit inside our 50mm cavities between the walls and the render-board. The solution proposed by the groundworkers and approved by our Building Inspector is to run them up the inside of the foundation wall before exiting just below DPC level. That gives us a potential cold bridge at each vent (26 in total!) but I think we can mitigate that by doubling the PIR insulation upstands to 100mm where the vents are. It’s not perfect but I think it will have only a very small impact on the overall insulation levels. Next week the scaffold is scheduled to go up on Wednesday/Thursday, then the timber frame is due to arrive the week after - when the fun will really start! Meanwhile next week I need cut the five 150mm oak posts to size and chamfer the edges, ready for them to go in to support the roof canopies over the front porch and rear terrace. (Six oak posts in the picture - I’ll choose the best five!)

Fill out your form showing minimal lighting, get the condition signed off. install all first fix wiring to all the places you actually want lighting, second fix minimal lighting as per approved plans, get house signed off. get electrician back and fit the lights you wanted. if I complied with everything I’m supposed to on my site, I might as well not live here. natural England wanted to know how many times we cut the grass. FFS.

@Hoops we had some remedial issues with doors/windows. The installers sent ASD Servicing for an independent inspection, to fix where possible and write a report for outstanding issues (almost sorted…). The ASD team were good - friendly, very thorough and informed. Might be worth contacting them? Looks like you’re in W Sussex, we’re midKent and so they might cover your patch. And really sorry to hear all the issues you’ve had. The self builder’s road is a bumpy one - so keep going, ask for help and it’ll be worth it in the end. Good luck!

I have lived in a large number of different houses and I agree that a traditional wet plaster finish feels best. If you can find a good plasterer who can do a good job with a bonding coat and a finishing coat then go for it. Finding a decent old school plasterer who can do it though might be difficult.

Great progress by the groundworks team in sweltering conditions this week - laying concrete blocks in the sun when it’s 30deg C and 80% humidity can’t be any fun at all. Despite the heat, by the end of the week our foundation walls are in and ready for the block and beam floor this coming week. We can really see the house take shape now, although quite a few of the foundation walls are just there to support floor beams and won’t appear as internal walls above the floor. As expected, it all looks a bit too small at this stage. It always seems to be the case that the foundations make the rooms look small. They’re definitely the right size on paper, so I’m sure it’s an optical illusion at this stage (hopefully!) The foul and rainwater drains are also now in place. Our Building Inspector ideally wanted the SVP to come out through the roof above the bathroom but since that roof is covered with Solfit PV panels (https://solfit.co.uk/domestic-solar-panels/) that can’t be penetrated, we eventually agree to put the SVP up the outside of the north facing wall. This is the wall that isn’t really going to be seen from the entrance, front parking areas or garden and we’d really prefer not to penetrate the roof with a soil vent if possible. So, everyone’s happy. The ‘spaghetti’ in the bottom left corner is where all of our external service ducts come into the plant room. 17 ducts in total, including two spare at present, (I may have over-catered): Power to ASHP Power to garden Water pipe to garden Water pipe to workshop Power to workshop Lighting circuit - switched external lights Data to workshop Live power supply in (SSE - single phase) Fibre in (Openreach) Water mains in (Wessex Water) Power to sewage treatment plant PV panel in PV panel in Power to EV charger Data for CCTV Spare 50mm duct (to workshop) Spare 50mm duct (to workshop)

Bitumen paint applied . Pretty warm today so will go over it again in 5 hours or so

The groundworks team have been putting in the Sewage Treatment Plant and drains this week. We’ve chosen the Klargester Biotec+ 2 STP and that arrived on schedule from Tanks Direct on Tuesday. Also this week the concrete pads were dug and poured for five oak posts that will support overhanging roof canopies - the Building Inspector asked us to put in 1m x 1m x 1m pads which seems excessive for 150mm x 150mm oak posts taking point loads of 5-10kN but it was that or pay the SE for (possibly the same) opinion. The team also started reshaping the paddock area - losing a huge amount of spoil and burying a lot of rubble that had been dumped by previous occupants. We'll probably wait until the autumn to seed it - not much chance of seed taking right now. At the end of a busy week there is not a lot above ground to see for all that effort but we needed to get this all done before the below-DPC block walls go in. Access to the rear of the plot will not be possible for the big machinery once the blockwork starts. The wooden garage mentioned at the end of last week's blog came down over the weekend (in the pouring rain) and has disappeared off site. The extra space created has proved vital - the photo below shows the concrete pad that's left after the garage was removed. (The wooden building that remains is a 5m x 9m workshop which is staying, though it will need re-cladding at some stage.) No new issues this week - hurrah! Fingers-crossed for that happy state of affairs to continue. The timber frame is due to arrive from Turner Timber on 7th July, so just three weeks left to finish the foundations and get the scaffold up. No pressure!

agree with that. My Google doorbell was/is battery, lasted about 2 weeks. "No problem" the missus said, just charge it. Easy for her to say, but it was me having to remove it every fortnight for the next 10+ years and that sounded hideous so i sent cables to it before plastering, job done.

We had a lot of room to play with, and ours dealt with it like this: As built, we ended up with a parallel-sided channel rather than the complex things the architect drew. It's important to make sure that there are decent falls all the way to the exit of the outlet into the downpipe. In our case, some of the falls were a little marginal. As the underlying USB has sagged a little over time, there are now places in the gutters where water pools.

If these are the architects own clients, maybe the issue is with the design of the build, not the ASHP? 🤣 You'll get dozens of replies endorsing ASHPs here, and few, if any for GSHPs.

But at the moment you can get a better rate for exporting your solar electricity and heating your water with the heat pump (with a CoP of 2 or more). And it's even cheaper if you can use a night-rate/EV tariff when heating your water with the ASHP.

As @ProDave says they are probably OK, but I personally would (i) check immediately under the joins for any evidence of dripping / water damage, and if so bite the bullet and replace them. (ii) don't disturb them unless you are going to fix them properly. The last time I got burnt by a joint this bad was about 40 years ago (I am not a professional plumber but only have done the plumbing on my own houses). In this case I left it but the joint then failed after I replaced the CH pump. I couldn't resolder because it was at a low point and I couldn't drain it down. I ended up cutting out a section and managed to put in a small insert with two new end-feeds. When I got the failed bit out and looked I found that the plumber had never actually soldered one side: the flux and gunk were all that was sealing the joint! Nick is the expert on this. He is my Sensei. 👍

By the way. My timber frame is up. Roof is due on next week. In IP8 if anyone wants a look next week.

We had a sample of this stuff and it was very impressive. But for some of the sizes of our windows we would’ve needed 2 panels per window and so would’ve had a line down the middle

It's a moral failing. Someone at the council thought 'should we try and hoodwink £70K out of a council-tax-paying 'customer' for making a paperwork mistake?'. And the answer came back: 'yes, let's try it on'. And yes, Feynman was a legend.

Hopefully this will be of help! As the posts above, it is possible to meet Part L standards without undertaking the thermal bridging calculations, but it is challenging and would need very efficient building fabric to compensate. You do not need to be qualified or accredited to undertake the thermal bridging calculations. Anyone can undertake them, similar to producing U-value calculations, however there are 'modelling conventions' you have to follow to ensure the thermal bridging (psi-value) results are accurate, these are detailed in BR497. As a side note, the modelling conventions for producing U-value calculations are detailed in BR443. THERM is free software which can be used to calculate psi-values; it's not the easiest tool to use, but it's more than capable. A link to download the software is below: THERM Software Downloads | Windows & Daylighting If your building is simple masonry construction, you may be able to use psi-values from the Recognised Construction Details website, a link to this is below: https://www.recognisedconstructiondetails.co.uk/

External blinds are best, internal blinds ok. UFH run in cooling mode. Fan coils.

This is the energy chart for a 6kW heat pump, it's doing cooling but same power is used for heating. Over a 3 minute period it hits 1130W electric draw, then ramps down. Electric is the blue line at the top. So no big energy spikes at all. Our battery doesn't show any spikes either.

I made up my own secondary glazing to cover up my old double glazed windows. The noise reduction was quite amazing. Very rarely does it go above 20 dB now, and I am not far from a busy road. This is what I am hearing at the moment and it is quite breezy outside.

Open backed speakers like these typically should be mounted so that they are enclosed. It improves the bass, and reduces sound from travelling to whatever is above them. There’s also a fire regulation depending on what is above them. I fitted all mine inside a fireproof hood and the difference in sound quality vs just having them open was significant.

In real life you don't need to seal that interface. There's no way that fire can get through a zero gap. Plus wood chars but doesn't burn, plus the concrete and plasterboard will expel water at thd board ends. But a bco doesn't know that and wants to see an industry standard drawing and the same built. So use beads of intumescent mastic at the ends. Where it meets the roofing felt, what happens? Felt burns and drips flame. Then is there any board? The fire can jump next-door. I think you need to fireboard the soffit for a metre on both sides. But I havent checked the document.

Not updated this thread for a while but now the heating season is over it's time to consider where I go next - let call this an end of term report. Boiler review - Did I buy the right boiler Yes - unlike the previous boiler purchase. Very happy with it's weather compensation and low flow temp capability and by the time we got to early spring I'd settled on a WC curve of this. I still have a little niggle about it's output being a little higher than claimed min but it's close and I am running at lower flow temps. System improvements/changes I've ordered 9 Danfoss RAS-B2 valves to replace most of the drayton EB4 bodies (adjustable flow via selecting one of 6 orifices) Why? 1. majority of the rads are running orifices between 1 and 4 and in most of the rooms the difference between one setting and the next one (up or down) is too coarse and I need finer control to stop the rooms being too cool or overheating without TRV intervention. 2. I want to get rid of nearly all the wiser smart TRV's and replace with decorators caps and I can do that if I have finer control of the flow thro the rads. Leaving them on the rads just gives me an expensive battery powered room temp indicator (where I need to replace that batteries every 300 days) 3. Replacing the TRV bodies means a drain down and that's an opportunity to re-configure the rads from BBOE to TBOE and tweak a little more efficiency out of them (5%) and I think it might help increase the delta across the rads It's quite amusing to think 4 years ago I was 1. running a boiler that was capable of producing 5 times the energy compared to the heat loss of the house. 2. Running the boiler at a temp that was only ever condensing in the warm up phase 3. Micro managing room temps with "smart" TRV's to heat only when needed via scheduled heating (over zoning) to now 1. running a WC boiler at a max flow temp at -2.5 of 34 Deg C so is condensing all the time and running at 97% efficiency 2. Heating 24/7 with minimal zoning 3. Planning to drop nearly all the smart TRV's and just controlling the room temps with WC flow temps Weird journey when you think about it............

Don't listen to the blind company, they're not electricians and almost certainly clueless. I'd be feeding them all above the bifold from one supply/spur.

In my experience, over tightening of bolts is the main issue in metal failure. Not only can it damage the thread on the bolt and cause it to fail, but the abrasion of over tightening can remove the protective layer around it causing another weak point. Torque wrenches are as much about preventing over tightening than they are about tightening to a minimum torque. And don't even get me started on split ring washers and them actually increasing the failure rate of bolts.

Re steel rusting. I've seen completely wasted structures, usually indoors in an aggressive environment. But also steel that's been exposed to the elements for 40 years, with only red oxide paint, and it is still sound.... it wets and dries again. But in or near the ground I'd say it should be rigourously protected. Perhaps galvanised, certainly painted, or both. I have a lot of time for bitumen paint....easy to apply and then slurp more into the welds and corners.

Welcome. Is it his customers who have complained about noise and performance, or is he repeating the Daily Mail's opinion? Agreed GSHP is a lot more expensive. Even assuming you have the space for a GSHP, chances are it'll cost at least £10k more than an equivalent ASHP. They're also rarely specced in the UK so there isn't much knowledge about them in the industry. For that reason, from a performance perspective, I think installing a GSHP is as big a risk as installing an ASHP. Having too small a field (or bore), or burying loops at the wrong depth, or if you have ground that is sandy and often dry - any of these factors can lead to poor performance. We've had a 5 kW ASHP on our new build for nearly 10 years. It hardly makes any noise and has had no problem at all handling heating and hot water for our ~290 m2 house (admittedly PassivHaus-class insulation and airtightness, and we're in the South East, so not much energy required, but still). Until last winter, I'd been running ours with a base flow temp of 25°C, with a bit of weather compensation up to the high 20s in very cold weather. I now run the base temp a few degrees higher, and keep the heating period concentrated around the cheap period, so I use less energy in the expensive period.

This was just me wondering, no one is particularly right or wrong. Obviously, it depends on skills, time, money and attitude. We are doing it block by block as our budget is <200k for 240sqm barn conversion. This requires 2.4m underpinning and we couldn't even get anyone to quote on doing it. So, rollup your sleeves and get on. Hence we are doing it in phases, like building 5 mini houses until we get to roof level. I'm not sure what happens then though. One real advantage though is you've got time to make decisions and rectify any mistakes when they happen (we've made a few)

Well that sounds an interesting project. Torque settings, to me, suggests a rather finer level of engineering sophistication that I associate with residential construction. Maybe steel frames for skyscrapers would? But I suspect not. >>> Is there something I should be considering? Well obviously the thermal detailing is hard around structural members that are good heat conductors. I expect some marmox blocks somewhere involved as a compromise. You’re happy with the expected life of screw piles? Sounds a great project, have a drawing or two?