Nickfromwales

Do you have a picture of that area of pipework? Tbf, without one nobody would have expected that pipe to be there / for them to be congregated so densely. I take pics of everything before laying, saved my arse a few times.

Historic regs will say you can have as many radials spurs as you like, whereas more modern (but still historic) regs (applicable here as it is not new works) state a max of 2 radials off a ring main; taken from wherever is practical / possible. Any time you can limit this then you should do so. Cable entry points on the rear of the socket will accommodate 3x4mm2 cables, or 4x2.5mm cables, but that is the least desirable. Not sure if / where this is stated in previous (16th & 17th) editions, but I've been doing this for 30 years and know what you can and cannot do. Option 1 is preferable. Option 2 is the worst possible solution, avoid! Option 3 is doable.

Panic ye' not. https://www.plumbingsuperstore.co.uk/product/internal-reducing-set-35mm-x-15mm.html?gad_source=1&gclid=CjwKCAiA3JCvBhA8EiwA4kujZiTSwgQH7eTA1H_Fsvtoka306J14zPpsT6Ocg-8yMTrcwhMMv8bUzRoCO_YQAvD_BwE It's just an internal reducing set. You can replace it with a 10p 22mm olive and insert 22mm pipe straight in.

Yup, it stinks! Defo get a friend or family member there howsoever you achieve this. Have them record sound on a mobile device so you don't miss anything important.

Use the hole-saw (Erbauer one will be a stronger option) to first drill a template hole in some waste material such as 12/15mm plywood / OSB. Then, lay that on the item to be drilled, with a knee on the wood or clamps. Use that to prevent the hole-saw from 'departing' and use high revs / little downward pressure. Bobs your Uncle, no need for Fanny. The critical thing is to keep the saw at 90o to the workpiece, and do NOT stop drilling until you are 100% sure you are through the metal. A good option is to put timber under this so you have something other than air underneath the cut (keeps the saw trained right the way through the cut)

Manufacturers often give the correct vessel > UVC A more relevant question would be whether these were delivered as a pair by the manufacturer, or sought interdependently (therefore possibly the EV was / is undersized). I routinely oversize, particularly if there is a hot return circuit (HRC) as the additional volume of heated water in the pipework can often tip the scales. THis is usually stated in the MI's, so should be mitigated by design anyways; but there are plumbers and there are plumbers...... Domestic cold mains rarely exceed 6 bar static, doubt this is relevant here due to the pattern stated.

I meant to wrap this up by saying your airtight envelopes will be a little convoluted maybe, so MVHR (and this important source of heat recovery) will need serious planning and a LOT of forethought I hope your team have good M&E roots!

Amen. @NailBiter, chop chop!!!!

You can say "Thermal Mass" as many times as you want, it's fine; we all know what we mean / what is meant / time to move (not necessarily swiftly) on.... Becoming energy rich in the summer will allow you to 'bank' for the winter, so a well-performing dwelling will still be manageable in terms of energy / costs aka "green credentials". Solar plus batteries here should be a no-brainer, but even without these a heat-pump based space heating system will make running costs 'acceptable' vs the alternatives. Maybe sacrifice the renewables at the outset to get more spaces with plaster & paint + floor coverings, and just cable for the solar et-al during 1st fix? 10 years is a long time to be looking at very unfinished areas, plus the cost of the renewables buys a lot of m2 of boards etc. Your choice of course, just saying... Airtightness will be of paramount importance with a dwelling this size, but you will need a very good 'team' around you to design out the multiple function living modes of this arrangement (I'll call it that vs a house, if I may ). Having a passive raft or similar long thermal time constant store and 'emitter' will offer huge dividends, so avoid skinny screeds over insulation wherever possible; another place to 'bank' cheap energy. Your architect is a good sort, as ploughing loads of expensive resources into cooling is the anti-energy efficient model you crave. Having a considerable cooling demand is way worse than a massive heating demand, IMHO, as I would much rather be slightly cold than slightly "too warm"; you can get cozy but you cannot escape excess heat. Consider solar-reflective glazing, or even better, solar (external) blinds / shutters. The latter will massively reduce summer overheat issues but will retain maximum solar gain for the winter months. As far as construction method I am a huge fan of Nudura, and it was a no-brainer for the build I am undertaking this year (for a client); 1800m2 over 4 stories (580m2 basement + GF, FF, 2F) and as you say, getting smaller as it rises. You have (again IMHO) chosen well there, for this particular instance. However, with the way it sounds like you're 'arrangement' is set out, do not discount timber frame above ground. MBC's twin-wall frame with blown cellulose is a fantastic solution, with outstanding acoustic deadening / great levels of insulation to boot. I am not a fan of SIP's at all, and would have this as a budget driven, last option. Horribly acoustically transparent. Please avoid this for your roofs wherever possible.

You talk to building control They don't bite mate! They will tell you what's needed etc and will help you to the finish line.

As the rooms will be leaking air in from outside, the MVHR would be a very bad idea IMO, and the likelihood (as the fan will need to run 24/7/365) is you will go backwards not forwards in terms of benefit. You may as well leave these bits of heat ebb into the heated envelope and go towards the space heating demand, and then deal with air quality in the study as you best see fit. When you calculate the very minimal heat recovery vs sucking in constant cold air from outdoors, I cannot see the numbers adding up. Spend the money on draft proofing and possibly filling cavities with insulation to improve the overall heat loss of the house, and that should be a far better bang for the bucks

I'd say he just wants to do a proper, thorough job tbf. And it would be many hours of testing to be thorough. It's also not great work, to come in and test someone else's work (especially a non-qualified home owner aka DIY'er) and then put your name to it. I would do as he suggested and go the BC route, if you are capable of completing the works?

He wants something for the filler to be able to be packed in against, so @Onoff's suggestion is kosher. Just foam it, leave to cure, scape back the foam to leave the depth of the plasterboard as the void, and then fill. Best to primer the cut edges of the plasterboard with 50/50 pva/water first so the filler has something to key to.

If the bends are tight, you may still want to install a conduit for the duration of the bend only, to alleviate any sounds from 'creep' where the pipe expands when suddenly heated. If very tight, just install a 90o bend and play safe. Avoiding joints is great, but having to install some and knowing where they are is plenty good enough. Hep joints are bombproof, fear ye' not....

I foam in sleeves made from 25mm flexible conduit, and then pull the pipes through them. If that needs to be sealed up, squirt some CT1 around the pipe where it exits the sleeve.

Do NOT allow the hep to drag along the cut board, as these linear scratches are #1 cause of leaking joints. Can you install sleeves of 21.5mm overflow pipe in, and then slide the hep through them?

Yup. Makes the pan move about, and leaves a bigger gap to cosmetically seal around. Looks shart IMHO, and you'll defo notice how easy it is for the pan to be moved. "Don't do it"....

Nope lol, just crazy busy as works just exploded. I don’t straddle the grout lines so the glass is sat on a uniform tile, vs sat across 2 which won’t be perfectly level. Prop OTT, but the toughened glass is quite intolerable of point loading / contact, so best safe than sorry afaic.

It’s all good. Many ways to skin a cat. @Thorfun I will never refer you to the man of dubious grout colours. Stick with me lol. Just been absolutely crazy busy with work lately, shouldn’t complain, so I may have to get @Pocster to temp for me now and then

Just plan well ahead if inserting the reducers directly into the manifold, as they are a pita to remove. If there’s any doubt, use a 150mm long piece of copper pipe inserted into the manifold so you can get the clip on removal tool in play. Prob then best to use a ‘socket’ reducer vs ‘spigot’ to save having to buy a coupler. https://www.screwfix.com/p/hep2o-plastic-push-fit-reducing-coupler-15mm-x-10mm/7165f?ref=SFAppShare

Agreed, in principal.... but the price of a borehole is high. Would need estimating by the OP before we could vote / offer feedback on that. Yes, an immersion can work here. I'd probably swap the buffer out for a unit with the capacity to take 2x 3kW immersions, it would be a lot for 1 to take on and then you'd be stuck with a single point of failure (for the sake of bit more capital investment). I've installed several immersion based heating systems (temporary and permanent) and they work brilliantly, for cheap as chips money in installation costs, but you are then tied to a 1:1 running cost. Not really a huge issue when you look at bank-rolling this endeavour, and at how much electricity you can buy with the change!! More ammunition for changing the buffer would be to fit a much bigger one (500L) to utilise load shifting off a cheap rate tariff like E10.

Gordon Lewis is your man, you should be able to get contact info for him here https://www.houseplanninghelp.com/hph195-what-is-cellulose-insulation-with-gordon-lewis/ as I cannot remember his trading name sorry! I'll need him myself soon!

Looks like it will function fine if installed as per the diagram tbh, just down to how well the boiler can modulate / cope with low heat loads (when the rooms get up to temp).

The 3 port valve is a diverter and not a mid-position, so will only have the 3 wires (brown, blue, green/yellow) so looks correct at a glance. It simply gets energised to change state (central heating or hot water) so defo isn't a 4 or 5 wire valve . +1, get on the phone and get them both back immediately and tell then if can't make it work you want a refund so you can pay someone who can. Sounds like a wiring / configuration issue to me, but really hard to say from afar.

Defo get the power on and be 100% ready to fill and keep it on! I commissioned one in the arse of last winter and it locked out a number of times and froze solid....was a right PITA tbf Turns out it was just the flow rate set too high, but trying to reinstall the popped hoses with numb hands was 'pure bliss'