Ed Davies

0.3 l/s/m², assuming typical 2.4m ceiling heights, is 0.45 AC/h, not 0.3 AC/h. This is irrelevant. With normal scuba kit the air you breath out is dumped completely so water vapour and CO₂ content is got rid of completely. In an enclosed space like a house you finish up with the exhaled gases diluted in the contained air which you rebreathe so the purpose of ventilation is to keep the concentrations down as well as to get rid of humidity and contaminates (like VOCs) from other sources. (In neither case is getting enough oxygen a significant consideration.)

Exactly. The biggest hassle with home automation is configuring things (setting up which Wi-Fi to talk to, what its password is, what the IP address of the hub(s) is/are, and so on). If they start with the assumption of a cloud service then whatever they do will just make things harder for anybody who cares about reliability and privacy. Indeed but they do claim to be somewhat agnostic with regards to what's moving their IP packets around.

Notes on reflashing recent Sonoff TH16s: https://edavies.me.uk/2019/07/sonoff/

So how are you going to make sure that stays accessible?

(Even if there was a vacuum between the panes (which magically didn't shatter the glass) there'd still be significant heat transfer by radiation. Cutting that down a bit is what low-e (emissivity) coatings are about.)

Diary entry for the last time I went into TP: They didn't phone back. I ordered 3 × 2.5kg bags for £29.70 (incl VAT and delivery) on line the following day. That's the price for the 3 bags, not each.

Is it this one? https://www.grantuk.com/professional/products/air-source-heat-pumps/r32/ Anybody recognize it? The manual linked at the bottom of the page looks quite comprehensive. I'd guess far-east gubbins in a Grant box.

Is that separate from your borehole pump? I though you said somewhere you had a Polish pump in the borehole. If they're separate, why? Something to do with filters being vented?

A French drain can be either. I assume that originally they were just filled with gravel as, at the time they were popularised (1860s) by Henry Flagg French (hence the capitalized name), I don't think they had perforated pipe available in quantities to make its use economical. The key difference, I think, between a French drain and just a ditch filled with rocks is the use of some sort of filter to prevent silt getting in. Originally they put fine gravel on the outside and coarser gravel on the inside, nowadays we just use geotextile.

Just got round to watching the video. Something I didn't like was that it was a bit ambiguously worded about taking the heat from the extract air and mixing it with the supply air which might reinforce the misunderstanding some people have that MVHR mixes the actual air flows (not just transfers the heat).

@Home Farm remind us, what orientation do your panels have? Did you mention in another thread that your ridge is north/south so the panels are likely east or west facing? I was a bit surprised by your comment that PVGIS shows the optimum angle for your panels to be 42° for autumn, I'd expect it to be steeper but perhaps it's because of the orientation. If so it might be worth going into a bit when you do your spring update.

Presumably there'll be some sort of subscription service. But how much will that cost and what if the company goes belly up?

I've done 1 day's work on my house since the beginning of November. Lost a day or two due to a bad back at the beginning of that month and a couple of days were possible but very cold and I wasn't feeling well so stayed in. In the same 6 or so weeks in 2018 I did at least an hour or two's work on the house on 17 days. Out soon to do the last “bib” on the Veluxes. Might be dry enough tomorrow to tape it and another one up.

MQTT is a protocol over TCP which sends simple messages which are fragments of text (or other arbitrary bytes, I think, but that's not how it's usually used) which are often just numbers or bits of JSON or whatever. Each message is labelled with a “topic” which is a string which has the same hierarchical form as a Un*x file name (names separated by '/'). Some topics from my system: cc/power, dhw_cyl/coil/top/temperature, living-room/temperature, study/humidity. At the middle of the system is a broker which receives all these messages from various clients scattered around the place and passes them on to any clients which are subscribed to them. There are various implementations of MQTT. I use mosquitto which is in the Debian and hence Raspbian and Ubuntu repositories so it's just a small matter of apt install and away it goes (it's controlled by systemd). There's a separate package (mosquitto-clients) which contains commands to publish and subscribe from the command line. E.g., from my main Ubuntu machine I can subscribe to all the topics on the MQTT broker on my RPi (called ripple) asking for verbose output (i.e., starting the lines with the topic before the message) using $ mosquitto_sub -h ripple -v -t '#' metar/EGPC/dtime 2019-12-12T13:20:00.000Z metar/EGPC/temperature 3 metar/EGPC/rh 87 metar/EGPC/wind/speed 2 metar/EGPC/wind/direction 200 cc/power 210 cc/power 207 george/uptime_secs 2382.41 cc/power 208 esp/30aea4739ca4/uptime_millis 39507626 ow/28b21ac801000038/temperature 13.75 living-room/temperature 13.75 kitchen/temperature 11.81 kitchen/humidity 59.62 cc/power 204 cc/power 81 study/radiator/temperature 48.1875 The standard Arduino libraries for the ESP8266 and ESP32 have an MQTT implementation built in which seems to mostly work [¹]. There are also a few MQTT clients for Android (and, I'd assume, iOS). I use MQTT Dash because it was the first one I tried and it seems to work reasonably well. MQTT doesn't really have much idea of history; it only serves current values for topics (though you can set a “retain” bit when publishing a message so any client which comes along before you publish the next one will get the previous version and not have to wait until the next one is published - I use this for one special case but don't use it a lot). It's not, really. Just needs setting up what machine has the broker and what topic to publish to in each of the sensors and so on. But it only does part of the job, collecting data from various sources together into a stream - you still need something to do the logging and graphing. [¹] I've stopped using MQTT in my ESP32 and Sonoff code (I now use UDP) because of a suspicion that the MQTT implementation was causing hangs when it didn't cope with a flaky Wi-Fi connection very well (which also happen once in a while on the vAir monitors which I assume use the same implementation) but I'm still seeing the odd ones so maybe that's not the problem.

Any idea where has them in stock? Lots of places advertise them at reasonable prices but don't actually stock them. I have a bunch of temperature and temperature & humidity sensors connected to various things. My central logger is a RPi (running Raspbian with my Python code) but only one of the sensors (a DS18B20 temperature sensor which measures the temperature of the flow to my study radiator) is directly connected to that. The rest talk to the Pi via Wi-Fi: 1) 3 vAir [¹] monitors which log via MQTT. One does temperature, humidity, pressure, CO₂ and light level in the bedroom. The other two do temperature and humidity in the kitchen and my study. These are based on the ESP8266. 2) 1 ESP32 in the living room which has a DS18B20 running my own firmware which sends the temperature via UDP. 3) 1 Sonoff TH16 (ESP8266 based) in the kitchen with a DS18B20 running my own firmware to report the temperature in the fridge salad tray via UDP and control the power to the fridge as the fridge's own thermostat doesn't work properly. 4) 1 Sonoff TH16 with a DS18B20 with my own firmware underemployed in the airing cupboard to report the temperature of the top of the DWH cylinder coil. The DS18B20 directly on the Raspberry Pi is connected via a USB 1-wire bus master because I had one (originally used on my laptop) and because logging via the One Wire Filesystem (apt install owfs) was so convenient in Python. The more direct and, in some ways, more-convenient-for-wiring way to connect DS18B20s to a Pi is via GPIO pins. Unfortunately, AFAICS owfs doesn't work with that. That's a long-winded way of saying I've tried all the likely combinations except the one I'm about to actually recommend. ? So what do I think @Onoff would be best doing? Get a Raspberry Pi (any one with Wi-Fi that's cheap and available), connect the some DS18B20s to a GPIO pin with a suitable pullup resistor and use whatever code to is needed (must be documented all over the place but I haven't looked, yet) to put times and temperatures in a file then plot the results with a spreadsheet or whatever on his main system. The advantage of the Pi over an ESP8266 or ESP32 or whatever is the proper operating system which will be fairly familiar to an Ubuntu user who's comfortable using the command line and the availability of plenty of space for storage. With an ESP thingy you'd need to send the data recorded to another always on computer for logging which might not be ideal. [¹] Sadly the chap making these has given up. I think he wasn't charging enough, if he'd have charged half as much again it wouldn't have been too expensive but might have been worth his while to continue.

In my limited experience electronics either works or it doesn't [¹]. Intermittent faults are usually mechanical things like connectors. With any luck you've jogged something like that which will now work happily for ages but if it does fail again try reseating the connectors if possible. [¹] after you turn it off and turn it on again if there's any software involved.

To get appreciable heat exchange you need a lot of area. Some arithmetic is called for. Here's some I did earlier: https://edavies.me.uk/2014/03/mhrv-area/ which might give you an idea.

Coincidence, really. Latitude relative to the ecliptic (plane of the Earth's orbit round the Sun) is probably nearer 80° in February so that'd be about the right angle for direct sunlight but that doesn't see as much of the sky above so tilting the panel back a bit improves the input from scattered radiation. Just happens to be by about 20° so roughly cancelling the effect of the Sun being “below” the plane of the equator.

It doesn't need to be that complicated. E.g., when I was thinking of nearer vertical panels I did consider putting a pond immediately south of the house to pick up a bit of reflection. Not sure how much difference that would make but it'd provide some extra light, I'm sure.

It's more complicated than that. As you say the low angle of the sun causes it to travel through a lot more atmosphere so the light is absorbed and scattered more. One effect of the increased scattering, though, is that proportionally more of the light comes from the global radiation across the whole sky. Exactly. PVGIS said I should put my panels pretty much vertically to maximize yield in January but I've actually designed my house so the roof they're on is at 60° on the theory that that will only slightly reduce the yield on the brightest days but will significantly increase the amount of scattered light received on the hazier days. Having more even output from the panels would be better in an off-grid situation but not so useful on grid. I held a panel at various angles with a meter on the current range short circuiting it on a hazy day in February, could just see where the Sun was through the cloud, and found the angle which gave the most current. That was 60°.

Indeed, looking at how much sense they make helps give an idea if they're serious or not. However, more detail is needed. E.g, as you say £6 billion on insulation, etc, won't go far if directly spent on individual houses but if it goes into R&D and administrative and financial changes to make insulation more attractive then perhaps it could kickstart things.

https://secrhub.co.uk/election-roundup-on-carbon-energy-climate/ Handy reference, I suppose.

The point @Bitpipe was making is that it matters where in the UK you are: rules in England and Wales differ slightly, NI and especially Scotland are quite different in some respects. However, if you don't immediately make that distinction we can reasonably guess you're in England ?.

If you're piling anyway, how about putting the house completely above ground level and just letting the water flow under it so no need to mess with drainage other than water off the roof.

Couple of Scottish Water chaps turned up on my site one day asking if I was connected yet as they were looking for a leak. Nope and not planning to be. Had a chat about my rainwater harvesting plans in which I mentioned the back-up possibility of phoning them up for a couple of cubes of water in a dry spell which they seemed to think was a reasonable plan. Also, other companies might do it. E.g., the company which I usually get heating oil from is said to do a water delivery service for things like construction projects away from mains water.