MJNewton

I am in the midst of retrofitting an MVHR system and am wondering what, if anything, I should do about my window trickle vents once complete. I could just leave the cover flaps closed but a) I'm not sure how well they seal (probably well enough I'm sure), and b) whilst the flaps cover the inside hole the outside hole remains open (with just an insect screen) and so cold air can still enter the window frame cavity (they're multi-chamber UPVC). Whilst I am confident this MVHR system will be 'for life' I don't want to remove the potential for reversal and so thought expanding foam in the vents might fit the bill. It'll work (seal/insulate) well and I think should be removable if need be by hacking at it with a suitable tool and having a vacuum cleaner suck all the bits out. Any thoughts? Even just the advice to close the vents and get on with my life?!

The type with injectors/splitters should be regarded as "poor man's PoE" (no slight intended; I use a lot of it) and is not standardised (unlike 'true' PoE). It does have the benefit of enabling non-PoE devices to be powered (over Ethernet) though.

If I were you, and I was not so long ago(!), I'd consider getting a couple of books on the subject as not only do they help answer questions you've got (this/similar forums are also great, often better given the dialogue and peer discussion) but they also help answer questions you didn't know you had too! Two that really helped me were The Construction of Houses and Home Extension Manual: Both really good bedroom reading, or at least I thought so...!

It need not necessarily cost that much if it's just a straightforward extension. It cost me £350 for an 'architectural technician' to my plans for permitted development check, detailed drawings for full-plans building control and builder quote, and the engineering calcs for a steel beam and lintel. Whilst I can't help but feel I should've paid more I must assume he doesn't lose money doing these and so must find it easy to knock all this out for so little cost.

Compliance with the regs is (mostly1) just that - complying with the rules laid down in legislation. It is only a matter of knowledge and skill, neither of which necessarily requires a professional. Forums like this can obviously really help with the knowledge side of things, and often times even if you don't have direct experience/skill of a particular task you often find that you have transferable skills from elseswhere. 1 Issues can arise from *proving* you've complied with the rules which, in the case of notifiable electrical work for example, means formal qualifications are required to be held in order to (self-)certify the work.

Of course, it does need doing in accordance with the regs though.

Not of they are just extensions to existing circuits, which it sounds like these are going to be given the low numbers.

Uugh.. Makes a sad situation even sadder.

Are you sure? My understanding was that lenders have a legal obligation to get the highest price for a repossession hence they are always sold on the open market or at auctions within the aim to achieve (and prove) this. Any valuation thus has no bearing on the final outcome.

I always assumed the recommended 'flexible duct' connections to mean something more like this 'semi rigid'1 ducting: Relatively stiff compared to the 'soft' flexible ducting (it retains whatever form you shape it) but still unlikely to transmit vibrations and being much smoother inside (particularly when stretched out). 1 Not to be confused with the 75mm/90mm semi-rigid ducting used for radial distribution! *sigh* I've never known a subject have so many ambiguous terms. Please nobody mention plenums, manifolds, vents, valves, terminals or grilles!

Ah, okay, I can understand the need more now. I think I am still thinking that by the time you've found and fitted a solution the problem will have gone away, and hopefully never to return!

Given that the dependency on the immersion heaters is a rare occurance, is it not sufficient to leave the switches on all day when required with the thermostats preventing power being continuously drawn? If you're not using hot water heat loss will be minimum, and if you are then the stats will just top things up as required. I can't imagine there's much energy to be saved by having greater manual control in such rare circumstances.

I had a 750mm in the last house and that worked well. Shallower could probably still give some benefit.

I prefer to go a little deeper whenever possible (ie assuming availability of the chosen worktop) as it allows for greater worktop area when you've got things sat on the top at the back. It can also make plumbing at the back a little easier.

My Dad pretty much did away with any cupboards in his kitchen renovation and whilst it was felt a bit weird grabbing a mug from a drawer to start with I've since learnt just how much extra fully-usable storage drawers give you, particularly if they are of the variety that slide all the way out.

That's what I went for in the end and, as advised, it was pretty much a doddle. As TheDreamer said, the boards felt extremely solid afterwards too.

I was trying to see if I could find mine anywhere as people often ask where it was from but it seems it has long since been discontinued. I did just stumble across this one though (a DI-LOG DL1092 in case the link ever rots) which for £17.99 might be worthwhile for those not wanting to spend too much or go down the DIY route.

It is definitely the best method for testing the RCD protection of a single RCD or a complete circuit (ideally with timing measurement of course) but the only way to test a downstream RCD such as the plug-in types without indiscriminate tripping of an upstream RCD is to force an inbalance through that one coil and not them both as would be the case if leaking to Earth. Incidentally, my neon socket tester has a built-in RCD test function with variable leakage currents and whilst it doesn't perform trip timings (or detect neutral-earth reversal) it is nevertheless a handy cheap tool to have. I don't see many of this type around though for some reason. (Apologies for the incorrect rotation - the original is landscape though)

That won't happen as the upstream RCD doesn't 'see' the imbalance created by the downstream RCD test button. All the test button does is shunt a small current between post-coil Live and pre-coil Neutral and the effect of this is therefore only ever seen locally. It doesn't leak current to Earth like a 'real' RCD tester does.

Okay, that's good to hear regarding it being more solid. And yes, I've got a gun - great things aren't they. I think I just need to better exploit it. To be fair, all my usage with it so far has been to seal up gaps overhead and so I've been having to use a 300mm pipe extension on it (just something I lashed up; not something that came with it) which makes it rather more tricky to use neatly as the foam keeps expanding out of the end even once the trigger has been closed.

I did consider that, but given the ubiquitous availability of 'normal' expanding foam I figured I probably ought to just learn to go easy on it and trust the small(er) amount to expand sufficiently! I've also been confused by the reviews of many of these low-expansion foams as often they've said they expand just as much! Yes, and great stuff it is too - aside from the functional properties it also makes even the roughest of installs look so much neater! Hides a multitude of sins you might say. Reassuringly sticky too.

That sounds positive; thanks. I was hoping to get votes for the foaming approach as it just felt like it was going to be a whole lot easier. That said, even though I've got a controllable gun, whenever I use foam I *always* underestimate the expansion and end up coming back to something of a monster. At best it's a waste but in this case I don't want too much going out of the back where I can't see/trim it. I suppose I could just be extra conservative, even if it means going back to top up any shortfalls.

I am about to be fitting 100mm PIR insulation between studs (600mm centres) and am wondering what approach to take. I am mindful that my previous experiences with PIR boards have been mixed (generally okay) in terms of accuracy of fitting and that has always been with thinner, easier to handle/cut/coerce, sizes and so I am assuming it’s going to be even more difficult with this stuff. I am toying between two methods: 1) Attempting to cut neatly for a perfect friction fit or 2) Intentionally cutting small (say, 5-10mm gap each side?) and then foaming the gap. For both I’ll be taping for vapour control and possibly adding a barrier sheet on top. The first method requires more skill, which would usually lead me to believe it is the better option if achievable, but then I can’t help but think that actually the second might be better in all respects – not only easier (no corrective cutting/trimming, no bashing the boards in to fit, no concerns regarding less-than-perfect timbers etc) but perhaps also benefitting from a better full length seal along the edges thanks to the foam filling in all the voids (throughout the depth of the board-timber interface) whilst also providing a more secure fitting due to the adhesive properties of the foam. Any thoughts?

My understanding, from Table 5.1a of Approved Document F, is that with MVHR a kitchen should have an extract rate of 13 L/s under boost. With the commonly-used 63mm ID flexible ducting this means a duct airflow speed of 4.17 m/s (if my maths is correct!) if only a single duct is used. Is this what others have done, or have you all doubled-up to avoid noise which I understand can become noticeable above 2.5 m/s?

Thanks, that's what I was thinking (and planning, as this is a situation we're in). Apologies Sjk for that temporary diversion.