Nickfromwales

Might be a good idea to get the plumber to T off those and kick the pipes back to the wall, terminating them in 2x isolation valves, even if you don't use them. Means not having to drain the whole system down for the sake of £60 worth of bits, and you'd need the isolations in the downstream install if you did proceed anyways, for service and maintenance or repair etc.

I'd invest in less invasive and more passive mitigation tbh, like the inline units, but I don't know the finite details of your build, or you, so cannot really add much more here Running redundant stuff is wise, that should cover your arse just in case

Depends on the remit from the client, as no two instances are ever the same. Further depends on whether there's a very good cold mains water supply, with plenty of l/p/m dynamic flow rate. As I've said elsewhere, I design and install to the requirement. I've always done a pipe / valve to each single feed to each outlet / appliance, as that's just how I prefer to do these things, as this is defo the better solution for equal flow / pressure to every outlet (comes mostly into play when multiples of outlets are being used simultaneously). One client wanted to have 4 people showering in different en suites, all at the same time, and also said there's a likelihood that will be happening whilst the kitchen sink or cloak WC was also possibly going to be used by other occupants, so I went 'nuts' on that one. Most UK homes have a scabby pair of 15mm hot and cold pipes run right through the house with all the outlets T'd off willy-nilly. They seem to manage so best to take with a pinch of salt sometimes, but also know it is fine to dial this back if it's just unnecessarily adding to cost with no real benefit.

Yes, I noted that, and I use Pex - Al with the aluminium liner as part of the MLC construction, hard as nails, you really have to pretty much maliciously damage it tbh, but still stops one from sleeping well in the hotel bed if done 'that way'. Done a couple, and it went well, but I insisted on being there and also having the pressure up to around 4bar for those ones. Conversely, on others, I rarely pressure test as the pipe is just too good. MBC don't test iirc, and they're putting this stuff in by the multiples of km's per month. I've heard of only one failure since 2016!! That client isolated one loop, and then all was fine (ish), and then said they couldn't really notice it wasn't heated for that part of the slab The joy of a passive raft and a well insulated, airtight house with MVHR!!

I did one that had a massively over-engineered slab (I think I talked the buffoon in charge down from nearly 300mm with a screed for the UFH down to 230 with the heating pipes inboard of the raft). Bonkers. This was a 1.5 storey ICF build, timber floors. The client has a 7kW heat-pump running UFH with 120mm c's; the idea of the tighter laid pipe loops is so that they can use the additional water volume and additional cross sectional area of pipe > concrete (surface contact area) to quickly chunk heat into the slab during pockets of cheap electricity, but more importantly to allow cooling to be done at a higher temp (to stay WELL away from the dewpoint). Is in and working well, but it's a huge thing to get to a set temp. Once it's there, it's very comfortable, just needs the stat to have the aforementioned tight hysteresis to prevent unwanted under / over shoot. Seriously consider the extra volume of pipe & water as it can reduce or negate the buffer tank

Nice job. I very much like the idea (simplicity) of installing the mesh atop the UFH pipes, as the UFH goes down very quickly and simply, just it pains me to trust the groundworkers to not damage the pipes during the steel installation.... If one company is doing the lot then it's managed and there should be some quality control and robustness of their procedures, but if left to Tom > Dick > Harry then I'll always prefer leaving the meat get off site and then I install over the top before the concrete goes down.

I have to say, the Illbruck FM330 stuff is very good, a totally different beast to the regular build-shed foams. I've had the pain benefit of being around some very elongated full new builds from day 1 to day Z (thanks to Covid) and have used this stuff for many different applications, from fixing things, general sealing, through to airtightness work and more; I've used it thick & thin! I've then been around it for anywhere up to a year, sometimes more at the plant rooms etc, after it was first squirted in, and I cannot recall any notable shrinkage with this stuff. I do make a point of spraying a mist of water, if adverse I'll do a 50/50 water/PVA mix, and this does help the curing process no end. It's also massively hardier than regular foam, when poked / scraped / cut into etc. Yup, I install the PIR with angled cuts, so there is friction for fitting, and a gap to get some foam into. Gaps aren't the killer here though, addressing airflow up between the boards is, hence me saying to foil tape over the tops of the joists from PIR board to PIR board (foil backed obvs) as the VCL.

Great, IF it's a 1 bedroom house yes? Factor in some redundant space for one, install cables and plumbing in abeyance, then add it later if needed?

If you do this as meticulously as you can, and get a score of <1.0 ACH, then that is absolutely going to be the best time and money you have spent of the job. You can have 1000mm of insulation in a draughty house, and still be sat there with the heating on full and be cold. Airtightness is where the rewards are really reaped; then you'll need MVHR and THEN the MVHR (HR) will look after you for life. Spend on 'fabric first', and enjoy the benefits long term. Quality doors and glazing next, then bags of solar PV after that. Prob after that will be a nice kitchen for the other half so you don't get murdered before the ROI is calculable, lol .

To add: 100mm, and with only 1x layer of reinforcing steel mesh too Thicker at intermediate junctions and ring beams etc, obvs.

Not IMHO, and even more so as it's the North elevation. In my opinion, you've been lucky elsewhere. Vapour is supposed to be arrested at the fabric connections, to seal the room, then the cosmetic layers get applied afterwards and decorated. You cannot compare this to a DPC as the DPC is at the foot of a wall only with the remainder of the surface left to 'breathe', so "no" . Next steps are: Go and scream loudly into a pillow so as to not frighten the kids, Take everything off and do it again properly. Drink beer when done. I genuinely think I should have worked as a therapist

@Nick Laslett HAS got this, and it's doing great, is what he's saying. Not sure if you're confused there, sorry. FYI @zzPaulzz, I have done a number of MBC PH TF M&E installations, (I got recommended directly by MBC or otherwise got awarded the project after MBC engaged), and there has been UFH in a 100mm constructional slab on EVERY SINGLE ONE . I have worked with many SE's to date, and found Hilliard Tanners to be the most approachable and pragmatic by far (including myself designing foundations for ICF builds with insulated rafts + UFH etc) and they accommodated my methodology; only once they had suitably scrutinised everything I had sent them and they were then 100% satisfied to produce a design that we could then use on site to instruct the groundworkers to build the foundation from. I've NEVER fitted expansion gaps on a 'passsive raft', NEVER cut expansion gaps in anything other than much thinner and non-constructional screeds, and most were tiled over. Zero cracks / other evidence of cracking etc whatsoever. I always leave it a full 6-9 months to allow the slab to cure before applying the tiles, other floor coverings can go down much sooner, but the builds normally progress sympathetically to that timeframe being acceptable / possible. The running temps of the UFH in the raft are just so low the damn things don't move much at all, if anything! The MBC PH TF I have just moved clients into has a flow temp into the raft of 26oC, and I'll bet that gets dropped back 1-2oC by next winter, once they've got the house bone dry and properly acclimatised. 140m2 L-shape slab.

Not in my 30+ years "on the tools" have I ever seen this done, sorry.

Guess what you're doing tomorrow then

Oh! I just re-read the OP, then it gets worse. Defo shouldn't have left the other layer of PB in there, it'll be acting like a sponge and the moisture will then trap and..... it'll only get worse.

I think this may be one contributing factor, as the VCL should really be behind the plasterboard and continuous as part of the fabric of the property. If you paint a VCL over the plasterboard, then airflow and hot / cool convection can occur in the gaps between the insulation and the PB.

Hi and welcome. If somebody on here can't think of a way to do it, it can't be done lol

I install M&E systems and "renewables" for domestic clients who are, primarily, self building, some up to, and some at Passivhaus certified standards. I do not have a home that MVHR would work in, it's a airtight as a colander. The saying "builders house gets done last" is pretty accurate lol. One day.... The 'effectiveness' is decided at the design stage, and nothing gets actually fitted which doesn't do what I promised it would. I got a nice little award to stick on the fridge from the good people at the Sussex Heritage Trust for my M&E achievements on a £~4m Passiv / NZEB project, so I guess it must have all worked . Either that or the system blew up and killed everyone lol. Part O now gets far more attention as the lid comes off the UK's dire understanding of these things (the repercussions of building a highly airtight and very well insulated home). Worst at it currently are architects and the clients themselves, some don't understand it at all, some don't want to "set fire to the money" installing equipment they think they won't / do not need.... These heat / cool units go immediately prior to the fresh supply manifold, before the air gets delivered to the room. They don't need to do much, (if there's a quality MVHR unit with a high % efficiency rating for heat recovery) so with clever design and a bit of know-how / prior experience, these can be put in to work with barely any controls etc (dumb climate control), and then they just go about their business. In a true PH or thereabouts dwelling, I will often install a 1st floor thermostat (where there was no requirement / need for 1st floor UFH etc), and then put a zone valve on the heat / cool battery that services the 1st floor; this requires a second supply manifold to segregate the upstairs rooms (again, all done / decided at the design stage). For a smaller dwelling you'd just use the 1st floor stat to kick cooling into gear, dependant on a 'cool capable' heat pump having being specified, and it being on already doing cooling via the slab; you just tee off that primary circuit and pump a supply to the heat / cool battery.

I bought all the kit from CVC Systems. I'll ask for the product details when I speak to them next, as it's quite a few invoices ago There are 2 row / column, 3 row / column versions, giving different 'power' per unit, so I size according to the M&E requirement. Random internet pic: This kind of thing. This one is a heat only, as it’s not got a condensate drain.

Yes, IF you want it to be MCS etc (as far as I know). I'm not 'in the industry' enough to know if these little blighters ever go 🔥, but I assume MCS had stipulated this for 1 or more 'good reasons'. This advice was of 2019, but it had actually changed at the time or I asked and it was found out afterwards /whatever, so worth noting at the very least I guess? My 2 cents is to fit them where they can be accessed btw, but MCS (apparently) says otherwise.

There can only be one king 🤴. 😘

He’d have to drive 10 mins to find out

The 330 is certified for use where you need to be ‘airtight’ and is closed cell, unlike cheaper open cell foams from the sheds. The open cell stuff can promote wicking of damp / moisture, which you don’t want It’s also far less friable and much more robust. Normal foams will allow you to simply scratch away at them with your fingertip, but the 330 is a much tougher product.

But, without it people would be using cheap BZP fixings to hold solar panels, badly, to roofs. Because people like cheap short cuts. If one of those broke free and hit somebody you held dearly…. What then? Then you’d be screaming “why isn’t this regulated?” 😌. If your house burned down, because an optimiser set your attic on fire…..? Regs are there to stop people doing things poorly, badly, or downright dangerously; this isn’t just to save them, but also to protect property and 3rd parties. That’s been done here numerous times Where have you been? lol Any mcs certified company would likely not appreciate you taking to meat off their bone, given their company running costs / overheads etc, and most would (should) refuse to do that. Plenty of people out there who will do as you ask, they’re running the gauntlet unless they have evidence of every single thing you did from A-Z, including proof of fixings used etc. After it’s all installed, how the feck would they know?

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