Great_scot_selfbuild

Sounds like it. I'd agree with this as a holding statement. Don't be pressured into making a decision, especially as you say they stopped work on your build some months ago - they clearly weren't in a rush. Just be calm and measured in your communication (may require a lot of self-control mind) and as long as you are in control of the discussion in a clear and reasonable way then you have a better chance of achieving an acceptable solution. Prepare yourself to have to compromise and not be totally happy (I say this from experience). If you have conversations then make sure you follow-up by email to confirm what was discussed (even if it wasn't for any formal agreement), as it will give you a written record if it's ever needed.

@cjsparkey Thanks for this - I'm thinking about this on and off, weighing up if it's worth paying one of the VAT reclaim people or just DIY it. We're organised in our register of items that are VAT reclaim-able and copies of receipts. Any points to note in terms of lessons (good/bad/would do differently)?

I’m looking at an options of installing an instant water heater at the sink taps at the end of long runs. I have had more than one person suggest such an idea to me and I’m trying to understand the options out there. I’m not talking about instant boiling taps, but rather running only cold supply to the sinks, with an instant water heater at the sink to heat it at the point of use. Willis heater https://www.unventedcomponentseurope.com/willis-jacket-external-immersion-heater-complete-pre-wired-and-fully-assembled.html/ Stiebel Eltron Instant water heater https://www.stiebel-eltron.co.uk/en/products-solutions/Hotwater/instantaneous_waterheater.html We only have single phase, so are looking at the smallest options Has anyone done this, and what does the cost to the electricity bill look like? Noticeable?

Why not? surely the same principle applies to it getting damp / soaked and needing to be able to dry out? both Board & batten and shingle involves overlapping timbers which I understood would need the airflow to avoid mould. I know the area is small (250 x 250) but they're at the corners of the house and will take all the weather.

Will definitely still be insulating to some degree - just with our board & batten or our timber shingle, but it'll still need an air gap behind it. The steel has already been zinc oxide coated and then bitumen painted on top prior to the windows being installed. Finish has come up well in terms of protecting the steel (these paint layers were specified by the SE to match the protection on the steel ring beam).

I’m likely to just cladding timber the same as the rest of the build.

I had thought they were all of this type (push air to the sides as it leaves and follows the ceiling). Just did a search for those that advertise as ‘coanda effect vents’ - £100 per vent!?! https://www.epicair.co.uk/products/air-diffusers-gypsum-performance-circle?variant=48789368701213 @JohnMo all points received - I’ll add some extra columns to my spreadsheet where I’m pulling all this together 😁🙏🏻.

Ok, so I'm revisiting some of my MVHR design and I've found myself circling the following questions, without really finding the answers from any of the manufacturers sites (happy to be pointed in the direction of any reference material): Whilst I mention ender here, I'm not fixed on them as a brand - happy to take advice/ lived experience on performance / noise of other brands. 1. What is the largest number of 90mm ducts you can feed from a single manifold (single MVHR unit - looking at Zehnder Q600 sort of size)? 2. I'm interested in a quiet system; when suppliers were quoting for 75mm they were insisting on twin ducts per vent purely to meet the BR spec. I have now managed to confirm I can fit 90mm (through holes in beams - I had previously worried 90s wouldn't fit, but they do). If I fit twin 90 per vent, will this just make it even quieter by reducing the flow rate per duct even further but still achieving the BR requirement at the single vent? 3. My investigation into attenuators previously was because I was looking into a branch system and needed them to avoid cross-talk; would an attenuator on a 90mm duct as part of a radial system reduce the noise? 4. I have a limited number of holes through the glulam beam, and so it would be preferable to achieve quiet running using attenuator on a single duct rather than running twin ducts. 5. If I had twin ducts feeding into a single vent, is there a single attenuator that would receive two ducts and then go into a single vent? 6. Has there been any study (formal, or just based on experience) into the noise difference between attenuator and multiple ducts. For upstairs, almost all our vents will be wall vents. We have 90mm studs and the duct is 90mm (having offered up, it'll fit). Where we put the ducts in the stud wall, I plan to line the wall with 9mm OSB either side before plasterboard. The studs will have rock wool sound insulation. 7. How much space is needed for the 90degree wall vents? 8. Although the 90mm zehnder duct (off-cut) I have offered up looks like I could get it to work, I would also consider the flat cross-section ('Flat 51' as zehnder call theirs), but note that the actual cross-section is less than 90mm; if I use these, do I need to double up (not according to their spec sheet), but I'm concerned about space and the practicality of bending them into the space available. Thoughts?...

@Nickfromwales I’m trying to picture this but struggling - do you have a photo you could share? I’d be using it externally, as well as possibly internally (though internally I imagine I have more options available to me). Was this alu profile a complete covering or just on the edges to butt up against the window? @JohnMo @Nickfromwales any recommended suppliers of compacfoam? It looks muck easier to work with than aerogel.

@Nickfromwales it looks like compacfoam is an alternative to the aerogel(?). This prompts two questions for me: 1. How do you fix it to the smooth steel column? (I understood @Super_Paulie‘s comment to imply they used a foam as an adhesive - I was picturing something like the foam glue used on my caberdek boards by the installers). 2. Have you used both aerogel and compacfoam? Why opt for compacfoam? (Not a challenge, just understanding why) Thankfully this was where I ensured we got a good quality (50mm) thermal break underneath the column - something I spotted as being omitted from the design.

@Super_Paulie are you saying you attached the aerogel with foam? I have a similar vertical steel column that needs wrapping on the outside (it’s a corner post between two full-height windows).

@NCXo82ike I can empathise. Had similar experience and it was only because I’d done my reading & research that I spotted our cold bridge and managed to get a thermal break in before the steel dimensions were finalised. Close call!

Yes, thanks to this group, this is almost my first question to the supplier. If I’d became clear they didn’t understand modulation (some didn’t), then they ruled themselves out. The Nibe I’m considering does have good low level modulation.

The ASHP market is a bit of a minefield, and I recognise that many will have their own preferences. I’ve done a lot of searching/research and have a quote that I have all-but committed to. The company does also supply and install other makes (Vaillant, Daikin to name just a couple), but they have started to install more and more Nibe. I’ve had Nibe recommended to me personally, and have heard positive reports about their user interface in particular. So, whilst I am still keeping an open mind and will take on board recommendations about other brands, the main reason for this post was as a final check for any reasons why I shouldn’t get a Nibe (installed by an approved installer with a 7year warranty). thanks

Useful tip - TY

I’m looking to put another layer of sand & cement wet slurry mix on our beam & block floor before starting the DPC & PIR. This would just take out a couple of imperfections (fortunately the beam lengths are short, so we haven’t got difficult cambers to cope with). The b&b floor had some slurry put on it initially, but a lot has happened since then and l’m looking for it to help make sure there aren’t any noticeable air gaps under the PIR board. I don’t have a cement mixer and would like to do. This without having to call the builder in for this part. Grateful for some specific practical advice / instructions.

Thanks @Gus Potter, a useful reminder to follow the ‘KISS’ principle. I’ve been wondering about the strength of these pipes once they’re laid (before screed goes down) - some of the spacing is quite narrow, do we need to make sure that no-one steps on any of the pipe once it’s laid? (I’d have assumed that the practicalities of a building site would make this very unrealistic) I’m not doing the loop design myself (I’m drawing the line at buying a windows laptop just to use LoopCAD), and although the suppliers don’t share their designs before we commit to using them, we’ve had some say their design has 7 circuits and others say they have designed for 11 circuits. Are you advising that we make sure we ask for more than one circuit per room for the redundancy (just to make sure they factor it into their design)? Almost always ‘no’ 🤣 Thanks for the reality sense-check

Well spotted (I know a little and am learning a lot fast) - looking at GIRA app control, but not seen what the other hardware and equipment will be. Good point, it may be very little indeed. I’ve added this to the list of things to discuss with the designer. completely agree here, just trying to make sure in making one choice I don’t *unknowingly* create a problem or challenge elsewhere (it’s fine if I’m making a conscious choice aware of the implications) - part of the reason for asking this question is to glean any experience and knowledge from others who might do things differently or recommend things that worked out well etc. I like the sound of all of this, though not all applies in our design. Added to the list to discuss. Thanks @joth

Missed off @jimseng from here. How do people learn about calculating the heat output from UFH for a given room size and heat loss? Any recommended books/reference material/youtube accounts/online courses? I’ve been wondering how the downstairs heating might perform if we had wider spacing in the living room compared to the other areas, and where to put the thermostat as the whole of the GF will be single zone 🤔🧐. Even just as an exercise, I’d like to be able to work through the calculation as an exercise. Has anyone done this before?

Couldn’t agree more - fear not, I do this too 😁👍🏻

Where to start. I'll try to set this out logically. I thought I'd landed on a plan for how to go about the ASHP (and by close association, UFH), but as we're now going for a smart home using KNX, the ASHP we were looking at doesn't have native KNX integration and so I'm taking a fresh look at this. Many of my issues chime with that of ___ in this thread - https://forum.buildhub.org.uk/topic/46547-how-can-i-roughly-calculate-ufh-output-at-given-flow-temps/ Bottom-line: We need an ASHP, 300L DHW cylinder and UFH design. Passive-level of insulation & air tightness (MVHR planned - DIY, Zehnder Q600). Ground floor height = 3m, First floor is into the roof space (steep pitch) - ceiling = 4m. Open void at the entrance to a double-height space. UFH - 111sqm ground floor only, single zone, spiral pattern, multiple circuits. Upstairs will have electric towel rails and UFH mats in bathrooms just for the ‘warm floor’ feeling rather than to heat upstairs. I’d like to vary the spacing so that the single zone system heats the rooms at a different emitting rate (bear with me) - the thermostat will only be set in one location, whilst there are 5 separate areas (living room - no opening window), study (small, has an opening window), hall (massive tbh), WC (tiny), Utility room (clothes hanging to dry), Kitchen/diner (massive and huge sliding doors). I’m suspecting that I may struggle to get this ‘done the way I imagine it could be’ as all the companies just roll out a default - same spacing everywhere plan. AC - detailed modelling shows we don’t need cooling, but we’ll install power to the locations where an AC unit could be installed, but we plan to live in the house without it. Shade is ‘not a problem’ we have plenty. Smart home integration - we’ve managed to get a KNX designer on board at a manageable cost and so want to ensure we can integrate the heating into it as the KNX controller could negate the need to duplicate having an ASHP controller separately. KNX is a protocol rather than proprietary system and so is widely compatible, but I’m looking to choose one that is directly compatible rather than via a 3rd party controller; I understand Vaillant and Panasonic are just 2 examples that are compatible. ASHP - I’m no plumber and lots of threads (here and elsewhere) refer to ASHP only being any good if they’re set up well, and getting someone who knows the specific make will know how to get the most out of it etc, etc. I’d love to learn this stuff, but I don’t have much time and this feels like something we should be getting done by an ‘expert’. The plumber (via our builder) doing the rest of the house is not familiar with ASHP and just needs a flow and return to connect up our UFH, but his only experience is system that have a buffer and when I started describing having a simple / optimised system with no buffer, it wasn’t clear to him. He’s clearly practical at all other aspects of the plumbing, but not one for designing a system. We’re approaching the point of laying floor insulation and being ready for UFH will be straight behind that. I’ve got UFH quotes for design and supply, but I’d prefer to need a plan, and the relationship between the UFH. Options (there are undoubtedly more that I can’t think of - it’s late…): Contract one company for ASHP design, supply & install, with UFH design & supply (some of the MCS quotes have insisted on having upstairs emitters as the calcs won’t work otherwise (apparently - I’ve got no way of knowing if this is correct). Rely on my heat loss spreadsheet calcs, purchase ASHP direct from a supplier (not sure how to install - is it as hard to set up as I’m led to believe?, do they come with instructions), get a company to design & supply UFH, lay the pipework myself and get our plumber to help connect it up, if we need. Something else?… Grateful for your collective advice on ASHP options that will be KNX compatible, and how to go about our design/install. Our journey so-far: Pre-buildhub days: NSBRC, Architect recommendations… approach ‘Renewables company x,y,z’ Single ‘do it all’ coherent blah, blah, (all sounds great until the crazy quote eventually arrives). Oh, how little we knew then! Local self-builder: Sheer luck, came across a local self-builder whose build was almost the same SQM, very similar passive-level performance, UFH downstairs only and only needs a 5.5kW ASHP (Samsung). This gave me a yardstick for what we would be expecting. Initial research: ASHP theory, all quite straightforward (in principle - reverse fridge etc…). Find a local ASHP firm that had a good sales pitch, MCS registered, quote didn’t take the ****, but scratch the surface and they really didn’t know the maths and understand WC curves and flow rate details. Seemed to very much be a UK office where ‘technical’ was more on the practical installation rather than actually calculating how the setup should be done. Buildhub reading began in ernest: Jeremy’s heat loss spreadsheet - https://forum.buildhub.org.uk/topic/439-fabric-and-ventilation-heat-loss-calculator/#comment-4407 (everyone seems to find their way to this eventually; I put this off for a while tbh, I deal with too many spreadsheets at work, I wasn’t actively searching for more). Measured everything up, ran the numbers, ~4.5kW before factoring in DHW. Quotes: Throughout this journey we’ve had blips of focus at trying to ‘commit’. We’ve had quotes proposing 14kW (WTF!), lots of default ‘buffer + pre-plumbed cylinders, no questions about UFH’ and the list goes on. Who to trust: I really struggle with working out which company actually has the competence to *design* the ASHP & DHW cylinder installation optimised for our build. DIY vs MCS: As I’ve learned from threads on here, the cost of parts can completely negate any benefit that the MCS grant suggests. There have been 2 quotes that have actually brought the cost down to zero/near zero through an MCS umbrella company, but I seem to recall there was another reason they put me off (will have to dig through the quotes & emails…). I would much prefer to have a system that we have someone to go back to if we have a problem (plus I don’t know if our building warranty will want some guarantee behind the install - just remembered as I type that I need to check this). Landing towards entrance void.JPG Hall towards plant.JPG Kitchen-Dining.JPG Living.JPG

We keep them all well stocked in a bottomless supply of decent snacks, drinks, tea & coffee. But yes, there will be beer at some point.

I'd seen it initially when it was all loose (waiting for the EPDM seal to be installed) and just assumed the black section with the splay would go down to the floor, that was all.

It's been a while since I had to work nights, and had various instances of particularly long shifts to press through. I'm definitely finding that they have prepared me well for this 'experience'! Personally, offloading some questions into this forum helps me. I have the notepad and pencil (tick), copious use of the iPad and the 'Procreate' app to annotate over images and drawings, but I typically find it takes a while to wind down from the day job and then spool-up some motivation to try and articulate the issue/challenge of the day. Then, a bit of Buildhub research before posting allows me to get the question out into the ether and hope that the following day an answer or two has nudged me a little further along. Secondly, radio 4 comedy shows are an easy listen and by then I'm normally shattered. Just know you're not alone in the challenge @ToughButterCup! Thanks for starting this thread.

Prior to the single ply seal being installed around the base of this soil vent I was expecting the splayed plastic section to be fitted to the bottom on top of the EPDM (not based on anything, just an assumption). It seems to be fixed in place now and I’m wondering if it is in fact to stop rain splashing upwards into the vent (just my best guess). I’ll ask my builder, but I like a second opinion from here. Scaffolding comes down this week, hence I don’t have much time to question it. in case you're wondering, no the window doesn’t open and yes it is far enough away from opening windows (laterally & height).