Nickfromwales

Took the words right off of my keyboard lol. Damn right. I'd rather put the other £800 into everything else.

You have a cavity wall / masonry build yes? If so, the foam will be subject to the conditions within the cavity, dripping condensation off a snot or tie etc, so I would use the rigid plastic for longevity. I'd use 200mm plastic through internal leaf, with the foam 180 inside that, and then lose the sleeve as you get to the inside face of the external leaf, drop the hole dia to 180mm and then punch through with the foam to the outside facade.

Get the stats from Telford too. "Go compare" lol.

If it is a generic UVC you are after, then you can also try Trevor at cylinders2go, and mention the forum.

I use the McApline on every install, and all projects are airtight etc. These just go to the soil stack wherever that connection is practically made. The G3 regs state the maximum length of the D2, including reductions for 90° bends etc, so you may have to beef that up to 28mm

👍

And have you started filling / sanding the FST for the Fermacell yet? If you gave that job to inmates, the crime rate in the UK would drop by 50% overnight. Seriously consider a plaster skim over those boards, it’s punishing work with very questionable results.

Get over it mate

The cold inlet is at the bottom, and water will take the path of least resistance to exit the cylinder, ergo the hot water at the top will make its way out. Me, personally, I don't like the "bubble-top" arrangements, as these need to be drained down periodically to regenerate the "bubble", and I would have an expansion vessel without a moments thought. Then you are at true '100%' useful capacity vs space / size.

Is the ply the final finish? I've worked on a number of MBC PH frames, from only being the M&E consultant and contractor right through to finishing complete homes (coordination of boarding & skimming etc), and can say with confidence that this is a non-issue. Self-builders are notorious for over-thinking and micro-managing, largely because they are face to face with every single tiny detail, plus they don't want to have to redo anything from un-investigated / non-mitigated misadventure (having often zero prior experience to fall back onto). One of the reasons this forum is so highly valued. On a SIP's TF dwelling that I am currently working on, I have recommended that the client use (x)mm Jackoboard / other generic insulation tile backerboard to suit each reveal. Also, to use this in the openings for the skylights / lanterns. You affix with multiples of screws (prob 100mm o/c max) or bond on with something like CT1, screws if over a membrane, or screws plus CT1 if any other (such as the airtight green OSB etc). 2 sets of skim over that and you're 2 birds one stone, and any worries long gone away. You can recess the back of those boards to accommodate the window fixings, as tbh these are the only significant cold bridges on an MBC TF (those and the skylights which they need to rethink their design on IMHO (sorry!)), remembering the TF is pretty much kosher and the issue is caused by the windows going in after MBC have done their bit. Using packers behind the PB fixings to create an air gap is probably more than suffice on an MBC PH TF, and is 100-fold better than what is in most homes at this moment, without having life-changing losses / cold bridges around windows!!

Hire a Spit nail gun. Will make clipping / mechanical fixings a doddle. No more drill / plug / screw etc.

It’s no secret that for MVHR I favour Brink equipment from CVC Systems. Whacking in some more of their stuff atm, and they’ve delivered great results on every install. Tres bien. 👌

Oh, and in a property that size you should do much better than 0.6 ach. The smaller the volume the harder it is to get a good score. Last few MBC TF jobs I’ve done have got 0.26, 0.27 and 0.25 results, as their airtight team are very meticulous, but I am even more so and bolster that with a bit more tape here and there plus AT foam anywhere that it looks like that would further improve things. @Russell griffiths got .28 on his DIY Nudura build iirc. That correct Bruce?

MVHR is requisite in an “airtight” residence, you’ll go purple and your eyes will pop out if you don’t install it. Not entirely true, but of course you will need to shift humidity and CO2 etc, plus introduce fresh, breathable air, so the “does / doesn’t work” comment I think mostly pertains to the efficiency and heat recovery values vs function per-se. I, personally, would just look at the highest efficiency and most robust (longevity) unit I could afford, and then I’d save up and buy a better one These are going 24/7/365 so have to be designed, configured, and chosen well to get the dividends. Any unit will ‘move air’ btw.

Let’s keep this on topic please folks.

I would take a blend of both. There are a lot of very well versed individuals on this forum, and I for one have zero ‘credentials’ to relate to building a certified passivhaus. However, I recently engaged with a PH certified architect, 25 years of PH design experience, and I got my design in at 88% efficient vs his 87%. He asked me a lot of questions, I gave very robust and reasonable replies, he conceded and the client then changed the MVHR design (well, the entire MEP design) and supplier on my say-so (and agreed to accept they’d lost £1k on the 1st design deposit). A PH certified home builder now builds differently, after 30 years of PH experience, after meeting me and hearing how I have approached creating homes that consider M&E etc and how we’ve integrated things on other clients previous builds. In terms of qualifications, I have a clean driver license, that’s it. But I do have bucketloads of tenacity, a passion for what I do, and an unquenchable thirst for knowledge. Most of the stuff I’ve learned has come from exchanges here, with invaluable input, argument, reason, and real-life data (there’s a HUGE amount of it here if you want to spend some time digging). One PH certified architect overlooked insulation in the foundations (😮), also didn’t have any clue about MVHR or space heating. Credentials coming out of every orifice, none that they understood or practiced well afaic. 💩 I’d rethink your confidence in ‘all that glitters’, as only a select few turn out to be gold… but I certainly do hope you have some of the best at hand. You’ll need it, as there’s a LOT to correlate and execute correctly at yours.

You’ll also need to dig out about 1m of trough to facilitate this repair, as the pipe needs to be apart by around 15-18mm to allow the union to be formed, then it needs to be pulled together by that 15-18mm to allow the inserts to seat into each side of the coupler.

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!!!!