Nickfromwales

Tell everyone to be quiet Works incredibly well in my house with my 4 kids. It doesn't work at all

Please don't shoot my dog because of what I said....

When the two sides are decoupled, I would argue that the improvements would be significant. But yes, as above, I would use the MF but again as 2 staggered walls to make up the one stud wall.

We're almost always fitting them in plant rooms, and we pretty much always line the plant rooms in 18 / 25mm plywood as there is just so much stuff to affix. CU's with us are straight onto that plywood, and then proper and full attention given to the fire integrity ( spread of fire from inside the CU to it's surroundings ) to maintain the standard. Yes, it won't hurt to make a nice fire resistant pattress for it, but totally pointless IMO as if that has been exposed to fire and has 'gone up in flames', you have much bigger problems to worry about at that point I assure you One thing we always do is fit a multi-sensor smoke detector in every single plant space, as early warning is what will pay dividends here, not what the 300mm around the CU is made from !! By the time fire / flames have got to that, the fire would be quite involved and the smoke detection system should have alerted the occupants WAY before the worry of how long the plywood will burn for is a question. Fire goes upwards as well as backwards, but upwards a HELL of a lot quicker...

Current endeavours have been to utilise the duct cooler, slab cooling, and when adverse conditions exist, a re-circulating duct system separate from the MVHR ( and in addition to it ) to target specific spaces with high flow cooled air movement. That leaves the rest of the MVHR serviced spaces on the lower fan speed and seems a more sympathetic solution.

Basement

You're over-thinking it perhaps? Why the fixation with nuisance sound transfer? Rigid acoustic batt in 89mm stud is about as good as it'll get if it's, room to room attenuation on the same floor you're looking for. Boarding and blowing with cellulose would add a lot of extra work too, as the boards would need a hole at the lower and upper voids ( above and below the horizontal noggin ) to fully fill each section x however many sections per the wall length = a LOT of holes to patch up. Main issue here is I doubt if it's physically possible to get the nozzle of the blower in to such a tight space, as if you've ever seen one it's like a huge curved darning needle, about 60mm in diameter, and not very sympathetic to getting into small / compact spaces... Cables in cellulose is a no-no unless seriously de-rated, but if you did one service void one side you could always just then drill services through, but then you would struggle with identifying cables within safe zones on walls ( where a cable rose and then exited the void horizontally to the other side ). Can o' worms there perhaps. Surely the acoustic batt will suffice, but then you still have the option of utilising SB plasterboard both sides, plus you could go to 15mm SB instead of 12.5mm standard PB's if it's bedrooms. If you're happy to 'go mad' then you could always make 2 thinner stud walls, say 50x50mm frame with the vertical 'studs' at 300mm c's, and just couple them horizontally here and there for maximum decoupling. Wouldn't be a pleasant task to try and keep all those skinny frames straight, and plumb though. Yup, and maybe you could do the split stud walls with the metal studs just slightly offset from each other, like one stud wall sitting in the space of the other, eg a pair of 50mm MF's making up a 100mm cavity stud wall but the two never meet other than the occasional strapper at 1200mm height taking the twang out of the wall. Would be a bit of a PITA to insulate with acoustic batt so you'd probably have to use a bit of loose wool at the MF intersections. Would the results be worth all of the aggro is the question... All these decisions will have knock-on effects too, like not having standard door linings for eg.

If it works, just walk away, OK

Better?

What's it set to now?

Already answered this elsewhere, but the scheme comes to and end on the 31st of March 2022, so if your'e considering a renewables installation then keep this deadline in mind. A scheme called the Clean Heat Grant is under discussion ATM, and if it has a green light then that will give people an opportunity to claim a one-off payment of £4,000.00, and is proposed to replace the under-achieving predecessor, the RHI scheme, which has failed to meet its targets for 2022 ( of 15% converted to renewables ) and is estimated to achieve about 8-10%. The CHG is, I believe, to dispense the remaining funds allocated in the RHI coffers. The Green Deal may also contribute towards the capital expenditure of a conversion to renewables, fortifying the RHI payments, so y'all need to do the homework, ask the questions, and get clued up before the RHI and the £2bn is gone. The above is not definitive, so do your own diligence please and ask questions accordingly, as some will, and some won't be eligible for X/Y/Z.

Assuming freehold, have you checked what you're allowed to store down there? Li ion batteries have a history of going en flambé.....

OK. Said colleague just rang me back; 31st March 2022 is the official RHI scheme cut-off date, ( so the guys quoting 1st of Oct are talking out of their arses, and are just high-pressure salesmen ). If this is installed after that date, you would then possibly be eligible for the ( under discussion ATM ) Clean Heat Grant which offers a one-off payment of £4k. The Green Deal grant which is now live I think ( England ) would also fortify your property with additional insulation / upgrade to glazing etc but I believe you have to pay a 1/3 and they pay 2/3's or something similar. Google will enlighten you there, but I think it would also extend to the installation costs of the ASHP now, you need to get on the phone as it seems you may miss out if you steam on unaware . Check your eligibility and leave no stone un-turned BEFORE spending a single penny.

Yes, but if it all goes horribly wrong then, no.......

'Cold mains priority' to the house if you do it that way Never have the O/S taps off after the PRedV as it hugely affects the available dynamic flow to the dwelling.

And a resale value too, vs a bespoke DIY timber shed.

Installed, with gubbings and consumables, that's about right, if not cheap!! Companies do actually need to make some money to stay in existence https://www.google.com/search?q=eddi+pv+diverter&rlz=1C1CHBF_en-GBGB910GB910&source=lnms&tbm=shop&sa=X&ved=2ahUKEwjUz-i0vZjrAhXLTsAKHfCBB2AQ_AUoAXoECA0QAw&biw=1280&bih=610#spd=988388954505620188

No need to write any cheques tonight

I'm going to the NSBRC on Saturday and I will then have ACTUAL facts, derived from a meeting I'm having there. I can update here once I'm all 'myths dispelled', and in possession of the details regarding the new Heat Pump Tariff also. Best you keep them at arms length for the moment...........

So question remains.....16mm2 or 25mm2 3-core SWA then. @ProDave ? 16mm2 won't leave much headroom over 12m IMO.

Best to compare apples with apples as the OP is in their situation, not the situation of others? Solar gain through glazing is, a little behind, linear with it's presence, but heating by other means, eg auxiliary systems, is by design and deemed ( known ) from feedback of the occupants being in habitation. Those events colliding to cause overheating ( from them being so far out of phase that they overlap or meet more significantly ) would be an error that you would have to strive to create as we're only talking about a model suitable for a 24hr period at the end of the 'day'. Seasonal adjustments may be required, but the fabric first rule resides over the auxiliary systems so the collide can be anticipated and mitigated by a wee dram of human intervention.

@Alexphd1 Can't you condense into that PV CU and steal that 12 way for the house?

Henley blocks into those tails, into a metal clad switch fuse with an 80A fuse, and then SWA between the switch-fuse and the house CU. Not sure on 18th ed specifics, but my spark refused to run 16mm2 tails over 18m distance, even off an 80A fuse, mainly due to it being an all-electric dwelling ( so assume he worked out the loads and insisted on 25mm2 ). Future plans for an EV(?) and can the EV charger be fed from the garage CU? If so, that would future proof the install against any adverse loads being added to the house CU retrospectively.

Is the second CU being fed off a 50A breaker in the first CU?

I'd always promote using a constructional slab with UFH though, as that's the most sympathetic method IMO and also lends itself to ASHP 'background' cooling. It does bode well for thermal inertia too, but the biggest benefit is deffo smoothing out the heating delivery. Have had feedback from folk who have built an insulated cube ( to PH standards, eg no slab / screed / UFH ) and the results are less than comfortable when in the heating season as most have had to use the MVHR for circulating warm air ( much higher airflow rates required / increased system audibility etc etc ) and have also had to employ auxiliary heating to fortify this via 'feature' radiators downstairs and towel radiators in every bathroom which are left on 24/7. Conversely cool feet vs very warm head was one comment.