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I just noticed no-one actually tried to answer any of your questions. I'll give them a go. I haven't quite done exactly what you plan, but I did handle the MVHR penetrations during the build and have run various additional cables etc over the years, through a very similar structure. How did you detail the penetration through the OSB airtight layer? Cut a slightly undersize hole in a piece of membrane (thick plastic sheet or film is fine) and push the conduit or whatever through it. Seal the edges of the membrane to the OSB with airtightness tape. Cut the membrane square ven for round conduits - much easier to apply airtightness tape in a straight line! Did you use proprietary airtight service grommets/collars or tapes around the pipe bundle? Generally not. They're expensive for what they are. At different times I've used offcuts of EPDM and DPM I had lying around. I've also used neoprene insulation a couple of times for cables. For example, I used a disc of thick neoprene insulation to run satellite cables through a snorkel on the roof, where I didn't want to disconnect the cables. I cut the disc a little oversized for the inside diameter of the snorkel, drilled some undersized holes through it for the cables, then cut from the edge to each hole. Slid the cables into the holes through the cuts, then slid the disc along the cable into the end of the snorkel. Neoprene is closed cell, so it was perfectly airtight. It's not a bad approach for running cables. Is it better to install a larger airtight sleeve through the wall and pass all the services through that? If I understand what you're saying, probably not. It's straightforward to seal a single cable, conduit, whatever, passing through a penetration. It's really hard to seal multiple cable etc passing through the same hole. We have one penetration like that, from the house into the attached garage, and it's a hideous nightmare that's probably responsible for half of the air leakage in the house. I suppose you could have one larger airtight seal over multiple holes in the OSB - if that's what you're saying then I think it'd work fine. How was the sleeve/penetration dealt with at the breather membrane and external cement board? Same as on the inside, but use membrane similar to whatever is currently in place. You could use non-breathable if that's all you have (e.g., just repeat what you did inside), as long as it's resistant to damp and whatever UV it might be exposed to. How did you deal with the condensate drain without creating an air path? We didn't have to do this, but consider whether you can run the copndensate drain to an internal drain. Alternatively, you could use a dry trap. We have one of those under our MVHR and it's worked fine for 11 years. Would you pressure-test the house again afterwards to confirm the airtightness hasn't been compromised? I wouldn't. Just pay attention to the detailing as you go and it'll be fine. On the underfloor cooling, we have a very similar Panasonic ASHP, probably an earlier model of what you have. It's very effective downstairs, but makes only a modest difference upstairs. Personally I'd consider installing aircon upstairs first, and seeing whether you can get away with mild underfloor cooling downstairs. It helps a lot if you have hard floors - tiles and concrete (we have the latter) are ideal. Not sure whether I'd bother if I had a lot of carpet. With wood floors, I'd be extra careful about making sure the temp is below the dewpoint. We had an incredibly humid couple of days in one of the hotter periods earlier this year, and we had literal wet patches appear on the surface of our concrete floors over the course of one day. They disappear overnight. I think the floors were probably only a couple of degrees below the dewpoint. I'm not sure I'd have been happy having that with wood floors.

Why is all the soil pipework UG? Suppose it doesn't matter anyway

Braver man than me. Still if it's not given you any problems yet. That invisible one is shit.

Hi We are at Groundworks stage on our build we get a monthly report from our private building control company with any outstanding queries. they have commented on Part O overheating to show functional compliance. Ive tried researching this online and the requirements aren’t fully clear I can see some companies online create a report for a fee? Is this just the case of getting them to confirm the design complies. we don’t have masses of large glazing and I understand you can’t site AC as a way of keeping the building cool.

https://www.theguardian.com/business/2026/sep/11/speed-up-electricity-grid-upgrade-or-else-face-higher-bills-warns-uk-watchdog Fingers need to be pulled out - but we knew that anyway.

We have an 11 year old Brink Excellent 400, and the criteria are similar (with the possible exception of the first one - I don't recall seeing anything like that in the manual). I seem to recall that some of the settings are adjustable.

Where does it all end??

Over the years we've had several of the Harvey block salt softeners and a Monarch and they all seemed to work without problems. The last one I had to buy for the new build was a Crown, but that was nine years ago. https://scalefreehome.com/harvey-vs-monarch-water-softener-uk/

Your concerns seem justified. I would add insect intrusion, wind damage and life expectancy (curling, splitting and rot). The one advantage might be light weight I think they might work better in other climates than UK, especially drier and colder climes. The damp UK will not suit.

Been there 3 years now, not a bit of movement, kiln dried timber with a near zero moisture content.

The key word is “reality”. These drawings are single discipline, unless you have provided a ‘line out’ of your other large bore services such as soil and waste pipework etc, so that is always the crux. Current project, CVC supporting and myself installing (and adapting the design to suit) on the fly: I changed a few bits around, and did my own thing with the manifolds to make it more sympathetic. Actual install when it was WIP: As you can see, I abandoned the square box manifolds as I had other services in some of the posi joist voids which took up too much space; these needed to take priority so needs must. It gets very busy very quickly, but this is a sizeable home (~400m2) and I had to get a lot of ‘stuff’ squeezed in. The MVHR install is considerable, but I have installed it all with ZERO impact on GIA; no boxing in etc, and CVC providing solutions to achieve this wherever I needed to reach out. It would 100% been a complete PITA to have to do this from scratch with no initial design, and I have a long history of such installations and am very capable, so any novice or DIY self-builder should defo reach out for support and CVC will do their best (based on the information you give them ).

Slow progress here and not much free time over the summer, hence taking 2 months to reply😴 If I get help in we will run head of the cash flow and I mostly enjoy doing it myself, or at least the satisfaction of being able to say 'I did that'. I put the garage up in August and BC are coming tomorrow to inspect the structure so the roof tiles can go on and it will be reasonably dry for the winter. The plan with the house is to get downstairs done for Christmas then fit the bathroom while I'm off work for the Christmas 'break' We should be ready for BC sign off early in the NY and I can finish the rest of the bedrooms as time allows.

The drawings are impressive, but how well do they match the reality of the installation? Were you able to follow the routes shown in the drawings?

Well on the one hand the custom schematic for my system shows a strainer, but then all V schematics I have seen do. OTOH my installers are V approved ppl so I could reasonably assume they knew what to fit, and I preferred the idea of a big mag filter at waist height in the plant room to a smaller inline strainer outside nr ground level. Also as less likely to clog on account of the much larger surface area. And I reasonably assumed that an Adey HP filter would be suitable for commonly used HPs if not expressly approved by V themselves - though to me it does look on the coarse side. Lastly it seems to be a personal view this year's man has expressed. Since in the two years since installation there has been next to nothing in the strainer and the flow rate is still a high as when it was first installed I am inclined to the view that if it is not broke don't attempt to fix it, there is plenty of other house maintenance I can be doing weather permitting. FWIW I would still be interested to know how to test the concentration of the Adey inhibitor without buying their dedicated kit for £64.09, I am not impressed by just having had to pay £20 for their two spare O-rings which the man also suggested having to hand.

FYI, I have used CVC Systems exclusively for nearly a decade and the service and support (both pre and post sales alike) has been absolutely outstanding.

Only the open plan area got the skim coat of plaster, that was due to its height and it would have taken me forever to tape and joint all on my own. All other rooms are getting tape and joint by me then painted. When I have taped and properly completed all the jointing and sanding stages I think it’s as good a finish as the skim plaster. Not every one will agree with that but I believe in Scotland it’s mostly tape and joint and in other countries particularly Canada that’s pretty much all they do. It’s definitely won’t change the airtightness as we are ICF so our biggest airtight challenges are the eves, service penetrations, doors and windows.

Ask your BCO? Ask your PD?

Noted, but I think the exact content is a bit tricky to find. Bear with us! What are the exact difficulties after getting from inside to out? This is where the PH ideology is a bit 'over-sold' imho..... You are where 'you are', so let's get this moving We need to know how much heat (energy) you need to move from indoors to out, and in particular which areas are worst affected so you get the balance of problem vs solution as close to perfect as is practicable. On my current (400m2), and next 2 projects (prob 3 now), I have recommended AC to the entirety of the FF, with no wet heating or cooling, for the little bits of space heating but non-insignificant cooling requirements that are anticipated. Solar control via glazing has been observed from concept, but ultimate comfort for the occupants is the goal; excess PV generation will delete any running cost of AC cooling, and any thimble of heating will just get paid for on demand. UFH/UFC to ground floor and DHW is via heat pump #1, AC via heat pump #2 (external units).

Most manufacturers have statements saying you must fit a given strainer size to keep your warranty.

Why do you need to lower humidity? Isn't that what your MVHR does anyway? On UFH in cooling mode keep flow temps at a reasonable level, as once you go below around 14 you can start to make condensation. Start at 16 and keep an eye on your manifold for any misting up. Slowly work down, but wouldn't go below 14.

SWMBO has chosen one with a small frame at the edge with the specific opinion that this will help keep spills on the hob. I think the flush mounted can look very cool (saw a white one in a white worktop somewhere) but do we actually want hobs where the boiling over and the spills and spits etc are free to run over the worktop ?

Had a service visit from Vaillant two weeks ago. He didn't find much in the filter (Adey Magnaclean HP) but didn't like the mesh size and said we ought to have inline strainers as well, as per Vaillant schematic. Last year's man didn't make any comment on this. I agreed it is a bit coarse (like a giant kettle fur collector but coarser) but said I didn't want to cut into pipe to add more fittings. He muttered about replacing blocked HX could cost >£1k and not covered by warranty. Previous oil boiler system had been cleaned with Fernox citric acid cleaner and their inhibitor used, always stayed nice and clean. HP installers used Adey inhibitor and biocide. IMO making sure the pH and inhibitor concentration are correct is best way of ensuring trouble-free operation, I have pH testing drops, man claims to have checked Adey inhibitor but I don't know what he used, what do other ppl do?

Looks like it may have been around a while but not catching on. So now you have to guess whereabouts to put your pans. So now you just destroyed that mobile phone someone left on the invisible induction area. So now it is invisible, except for the kitchen extractor positioned prominently above it. So now you have to choose a compatible worktop only.

Possibly the ugliest thing I have ever seen TBH !

We’ve done exactly the same (I think we followed Dreadnought’s recommendation) and it’s fine and dandy and a good price too. We’ve also got a Qooker tap. We fitted the Qooker Scale control, it’s another cylinder to go next to the main cylinder, or in your case a cube. We’ve got 33 whatevers hard water (yes, 33 individual little droplets from the test kit till it changed, sigh), and I think it’s a condition of the Qooker warranty that if you have hard water you have to have a scale control doberry. As an aside, why an unsoftened tap in the room of utils?