Great_scot_selfbuild

Thanks all - the fit is pretty good tbh

I’m busy installing PIR flooring insulation (on top of beam & block floor, to then have a dry screed laid on top. We have the DPC down, and it’s all going together fairly well. I understand expanding foam is typically used to help fix them all together and generally fill the odd gap (none are large). I’m worried about the foam getting underneath and lifting the boards. 1. How much foam is typically needed (assume the sheets are tight together)? 2. Any tips on installing the foam? 3. Do I need to be worried about the foam lifting sheets, or will it only really expand where there’s a gap for it to? TIA

Great to hear. We've had our Internorm door fitted and LOVE it. Definitely felt like a luxury spend, but we went by a similar logic - few bits of the house will have such a guaranteed impact. No fingerprint scanner though... 👏

@SimonD I'm interested in doing my own calculations on this. Whilst I head off and do some searching, can you help me expedite this by directing me to any resources / reference material that takes me through the process specific to sizing UFH to a room / heat loss etc? It sounds like this should be a lot easier than trying to dig out my thermodynamics notes from 20+yrs ago (I hope... never was my favourite, but now I'm more motivated 🤣). In an earlier post which evolve into a focus on the UFH layout / sizing I had actually asked about this - I was wanting to understand if I should be looking to tailor the UFH pipe spacing and design to each room, which largely received the response "it'll all end up at the same temperature, so don't bother" (I'm heavily para-phrasing). However, I do like to learn a new aspect of engineering and although I have no available time, I'll happily sacrifice some of my sleep to work this through myself. Would be grateful for a steer... (btw I did look up Rob Berridge and in the YouTube interview he mentioned that he provided training material but I can't find it; I've reached out to him, but no response yet). I'm still waiting myself. This sums up so many of my frustrations. How are the general public (i.e. me) meant to know enough to challenge the information we're provided. I've surprised myself at how much I've spotted, been brave enough to question and then, disappointingly actually, found out I'm right and something needs to be changed or corrected! (from architect designs, timber frame structural elements, roofing construction and roof light installation). Micro rant over. Thanks for this - I will be re-visiting the ASHP / heat loss calcs (though I know it's 'just numbers plugged into a software tool' - hence my interest in learning the calcs).

Well I have been pleasantly surprised by the UFH supplier - they understood my request to increase the spacing between the supply / return pipes, replace the utilities area and have re-done the design. Where they're still bunched close, I'll insulate so that there is an exposed pipe every 150mm. Here's the revised drawing for those who will be interested. UFH-FHW CAD Drawing Rev 2.PDF

Great to hear - thank you. Our ASHP installer is complying with the MCS requirements (which doesn't allow MVHR to be taken into account, and only goes down to 35deg flow temp), however, he knows exactly what we want and, importantly, he has done exactly the same in his own house, so there's making sure it can achieve the MCS sign-off, but able to modulate down low enough to run efficiently as very low flow temp. They even audited his house as luck would have it and it still met the requirements for the BUS grant, so after being initially frustrated at the MCS / BUS restrictions, I'm happy I've found an installer who understands how to comply with it whilst delivering what we want.

They knew exactly what we planned to do and we gave a very clear requirement. I'm getting very used to this 'quality' of output from the suppliers / distributors etc. now though. Speaking to my builder, it's entirely 'normal' and he spends a large amount of time fixing design issues on site. Unfortunately it also only works on windows and I'm loathed to by a PC or try and set up a virtual machine on my Mac just for this; this was why I went with a supplier who would be paid to do the design (having provided them with all the necessary information). #sigh... Is this a personal recommendation of this one, or has it turned up on a search (just wanting to make sure I understand before I look around). Thanks for the nudge. This is a good enough reason for me I think

@Susie Thanks! - photos of it in use is really helpful. We have spoken to countless people about the screed options and I was surprised that I have been advised that for dry screed (which were going for) we don’t need a membrane/layer on to[ of the PIR insulation as, although it’s pumped in, it’s simply not as runny as liquid screed. What type of screed did you lay on top? Either way, I like the approach of using the grid membrane @torre included a link to. Our ASHP supplier is working on the heating load requirements, and the UFH supplier providing the UFH design. I’ve asked for the additional design information beyond just the drawings, yes. @JohnMo 🤣 they’re welcomed! 🙏. Posting publicly is always a risk, and sometimes the best comments are those that challenge your (my) current position, either to present an alternative not yet considered, or to make sure the path chosen is done so in knowledge of the risks/compromises (which there always are), so thank you - very much appreciated 😁. 1. I have wondered about this - why the runs to/from the loop aren’t also spaced as the same as the heating yrs serving the same function after all. I’ve not had any design / response look any different to this (nor seen ones do it in the photos I’ve seen on this group - they’re all bunched together in getting to their destination). I’m going to ask I again, but have low hopes that they’ll have the skill or wherewithal to do that. I’m getting used to the professionals’ not living up to expectations, even when they just specialise in that one aspect of design. 2. Noted. 3. Not sure I understand what you’re saying? (FYI the whole downstairs is single zone, and provides heating up through void in hallway for upstairs). 4. Manifold is in the utility, yes. This is the first I’ve had anyone mention insulating pipes, though it makes perfect sense - can you please elaborate? (Photo appreciated, to help me interpret what this looks like before screed is laid on top). 5. Yes, and yet this seems to be the way the industry operates. I approached quite a few M&E firms but the prices were quite ridiculous. Would be ha[py to pay a reasonable fee, but not how they marked everything up and tried to oversell. Rather made me very sceptical about the whole lot tbh (on top of me having to correct some of the professionals I have paid).the spread of inputs from this group helps me balance out the options and weight it all up. I agree, it isn’t a design.

Thanks - I had read about this. I’ll DM you 😁

@Barnboy that is exceptionally helpful, especially with the photos added - very much appreciated. Chalk line ordered!

Given the challenge of getting a UFH design done, now that we’ve (eventually) selected our UFH supplier, I thought I’d share the layout design they have provided. I had requested a spiral pattern and first time they sent over a serpentine design. I’m pleased I checked it as soon as it arrived as they they re-ran it and sent the spiral pattern, but I do like having both as a comparison. We will be installing the pipework and now that we have a design to look at I’m interested in hearing advice on how best to tackle (practically) the layout. I’m purchasing a UFH staple gun and decoiler for the pipe. I’ve got a couple of weeks before we start this. My initial thoughts are to mark out 150mm spacing across each room in both directions (partly to double-check the design), and lay the longest loops first. Spiral configuration that we’re installing: Close-up of the longest runs:

I’ll leave the data analysis to my wife. She’s the clever one… 🤢🤮… 🧐 I think I’ll install one probe and have a connection to the plant room in case we decide we want to. thanks all - I’ve whittled the UFH quote down quite a lot thanks to input from here and it comes to just £1060 ex VAT for a 115sqm area coverage. Over £1k cheaper than some of the quotes I had in!

We’re installing UFH in a dry screed with an ASHP that has reversible function and may be used in a cooling mode. Ive read a little about floor probes, but our ASHP installer is saying they’re not required as dew point just requires us to know the air temp. 1. When are they required? 2. What for? 3. Where should I put them? (I’m having a single zone with 11 circuits across 6rooms).

We're planning our UFH as a single zone, open loop for the downstairs with only one thermostat. I've been round this a lot elsewhere and on this forum, but just before going ahead, our ASHP installer has mentioned that building control tend to want to see temperature control in each room. I've read the Building Regs Part L and it does mention zones, and there's a brief mention of low heat demand homes, but I'm asking here to find out what the lived experience is in dealing with approved building inspectors on this topic. Ours is very particular, and hard to get hold of to discuss questions like this (which I will try). In short - I'm wanting to know if anyone has actually encountered this issue, if they've had to argue the case, or if there's a simple way to phrase it to demonstrate it's compliant with the BR wording (screenclip of the BR section I've found on it). Thanks

Question: I know that the MCS installer applies for the grant on our behalf, but when during the process can they apply for it? / when does it pay out? Background / reason: I thought that we would only pay the amount remaining (full quote minus BUS grant) but we’ve had a couple of installers (small businesses) say we need to pay in line with their standard stage payments as they can only claim the grant after install is certified and then the final payment is taken care of by the grant, plus a refund for any difference. I realise many here will say just don’t bother with the grant, but on balance for us, we’re keen on going with the NIBE ASHP, which requires approved installers and comes with a 5 or 7 year warranty. I’m just looking to check that this pay / refund isn’t unusual or unreasonable. My only hesitation is making sure they don’t turn around at the end and say we’re not elligible. I hate not being in control of the process - can you tell? 🤣