Ed Davies

EPS is considerably more vapour open than PUR.

Yes, you could just upload it and he could just download with a web browser.

It's not just the cost/disruption of retrofitting. Some old houses did have UFH fitted and were horribly uncomfortable as a result. This was because they didn't have insulation (other than bricks, etc) so needed a high heat input which meant the floor had to be very warm which was quite uncomfortable in much the way that ceiling radiant heaters in a workshop or hangar would be but from the opposite end. This gave UFH a bad reputation. E.g., when I was staying in the static caravan my landlady's husband said the one regret about their pretty-well-insulated conversion of their house/B&B (they used one or two walls of the old house so it was effectively a new build, slightly older building regulations than current but they'd well exceeded the insulation requirements) was that they hadn't fitted UFH. They'd been put off by his memories of his aunt's old house which had been uncomfortable in this way. This adds to the warming not to extrapolate from hangars to well-insulated houses for ceiling radiant heaters. Ceiling panels will deliver a larger proportion of their heat radiatively [¹], rather than by convection. [¹] and conductively, but I think that's pretty much negligible anyway.

My feeling would be that it'd be unwise to seal up the bottom of your joists. Any water that gets into that area, for any reason, needs to get out as soon as possible.

Hmm, shall I believe what looks like a well-researched article in Scientific American which specifically counters this point or…

You're told unreliably, mostly.

Yes, that might be one approach. I'm assuming what you have in mind is that NFC would be used to tell the phone what the IP address of the device is. But it would need extra NFC hardware on the device that would be needed just once or maybe each time the router allocates the device a new IP address. Perhaps Bluetooth LE would be another option for this as it could at least share hardware with the Wi-Fi interface.

It seems to me there are two reasons typical IoT devices are controlled over the internet (rather than just the local intranet). One is simply to be able to control it from anywhere but that's a pretty niche use case. The other is simplicity for the developers. If the device has an internet connection it can get to their servers as can apps on mobile phones with hard-coded domain names. On the other hand, configuring IP addresses and so on for apps to find devices on a local network with different makes of routers and different operating systems on the phones, tablets, desktop computers or what have you is a lot more complicated and the cost of providing support could easily wipe out the income from selling one or a few devices. This is one (out of a quite a few) flaws in current internet architecture. E.g., it'd be very helpful if there was a standard way to tell devices which controller to report or listen to. Something like DHCP giving the IP address and port number of the MQTT server to use, or whatever. I think DHCP can transport that sort of information but I haven't come across any way of setting that up on standard domestic routers. Even if you do have to use a central server initially then perhaps it could work to just introduce the app to the device and all further communication could be done locally so at least your lights continue to work when your internet connection is down. But doing that would likely run into all sorts of support issues in the face of NAT where the IP addresses the server sees aren't the real ones on the actual devices. And so on.

I'd imagine so for circuit breakers and light switches. Don't know about socket switches; continental sockets tend not to be polarised so they're a lot more relaxed about the line/neutral distinction anyway and often don't switch the socket anyway.

It might not cut it for you personally but for others it might be more useful. E.g., a friend of mine and his wife both flew for different airlines so had weird schedules and, of course, possible delays getting home at odd times and likely somewhat jet lagged. Running the central heating for other than frost protection while they were both away, sometimes for quite a few days, would be a waste but getting home to a warm house would be very welcome so either of them being able to turn up the thermostat from Heathrow was something we talked about. Just for giggles I wrote a prototype shell script to watch for their flight numbers on some website or other with the idea that it could see when they landed. It amused me to think of directly (i.e., without human intervention) controlling the central heating off a 767 boggy tilt switch.

Totally irrelevant but something I find curious: apparently in Norway 3-phase into the home is normal but rather than the star connection used in most countries it's Δ so 230 volts between phases. So you run your downstairs sockets between, say, L1 and L2, upstairs sockets between L2 and L3 and lighting between L3 and L1 or whatever. Neutral/earth floats around somewhere in the middle of the triangle depending on your distance from the substation and neighbour's leakages on each phase to ground. Seems a bit bizarre but it does give the copper-saving benefits of three phase without having such quite high potential differences in the house. Sort taking the 110-0-110 systems common in the US to their logical conclusion.

No, the permitted development rules don't care if it's grid connected or not. They just need it to be removed if it's no longer used, presumably for the reasons @Temp mentions.

Have used the oil boiler for a quick burst in the morning for a few days now. It ran 9.4% of the time yesterday. Admittedly I've had the thermostat set relatively high as I'm a bit warm adapted and didn't feel that well and yesterday was very dark and damp which makes it feel chillier and also very windy which cools the house a bit. Outside temperature at Wick airport varied between 11 and 14°C.

It's worth noting in passing that Sonoff seem to have been improving steadily over time in this respect. John Ward reviewed one ages ago and was pretty sniffy about the current carrying capacity but was otherwise reasonably complimentary. I bought mine on that basis, thinking a limit of about 5 amps would make sense. Like @TerryE's photographed above mine is better than the one John Ward reviewed - shorter and beefier high current tracks. Mine's version 2.1 (2018-06-15) which is slightly different in layout than @TerryE's. A further improvement is that the earth pad is also tinned which would presumably make some fault situations a bit less fraught - if there's no RCD or the RCD doesn't trip you'd rather the fuse blew than the earth track.

Just to be clear, the inverter can produce more power than the approved amount of export power as long as the balance is taken as self-consumption (e.g., to the kettle, charging the car or house battery)? Interesting, I didn't realise any were like that. Does it use a current-sense clamp or something more solidly wired in?

What's the difference, from a physical point of view? I'd have thought they'd be much the same except that in a smallish closed gap there'd be less opportunity for convection so the surface resistances would effectively be a bit higher.

Right, so if there's any problem with that measurement it could export. DNOs only approved certain (one?) of the PV-to-hot-water diverter systems to limit larger than 3.68 kW PV systems to 16 amps/phase presumably because they had doubts about the robustness or fail-safe abilities of other systems. Of course, I was asking @JSHarris about the specific system he had in mind that physically couldn't.

Yes, the actual limit is 16 amps/phase so, so long as they're properly balanced across phases, you can go to ~11 kW without prior DNO approval. What stops your battery system from exporting to the grid?

For gap widths of greater than about 10 mm this gives a resistance of about 0.17 m²·K/W (increasing only slowly as the gap width increases) which is equivalent to only about 3.7mm of PUR. If that's right, I take back my comment about putting insulation there not making much difference. However, BS EN ISO 6946:1997 apparently gives a surface resistance for horizontal heat flows indoors of 0.13 m²·K/W and BRE Digest 108 says 0.12 m²·K/W. With two faces involved that'd be a resistance of at least 0.24 m²·K/W for the gap plus any contribution from the air itself. Additionally, a foil surface ought to have a higher surface resistance - I'd assume about 1.8 times but I've not seen any references discussing this. So I'm not entirely convinced.

Umm...

For small gaps insulation makes less difference than you might think as the air gap is insulation itself, particularly if you've got a reflective surface on one or both sides to reduce radiative heat transfer. There might be better uses for the money spent on any insulation there, maybe more insulation in the roof or something.

No, it was about the three eBay Senco ones in your first post; all three are 110 volt so would need a site transformer (one of those yellow blocks) to work off normal 230V mains.

Failing that, an IR thermometer can be very informative with a bit of patience. Not the ideal time of year to use either, of course, as you want a nice contrast between indoor and outdoor temperatures to see things clearly.

Why does the expression“third world” float into my mind?

Just checking, but you've got 110V anyway I take it?