Hadn't seen this mentioned but perhaps I missed it, more plumbing hardware than electronic, but perhaps useful for others.
Having tried a variety of plates and heat-sink compounds and tie-wraps to hold these little chips in position on small sections of metal pipe (my rads are fed with fused plastic pipe), I came up with the solution of using pipe clips, the cheap plastic variety from DIY stores and hardware merchants.
The first problem hit was with attaching plated sensor the the boiler clamp nut, it was off by 10c and no way could I get a more accurate reading, presumably angle? Finally found a pipe clip which got hacked in half to fit in the tiny gap in the photo... Some hacking with a Dremel, some soldering to a pin connector, some fiddling around with epoxy and voici....

The gap
The tie wrap in the top of the photo is the original plate mounted version which was "off"..

Having scored on that front with more reliable readings I looked at the roving radiator test kit and realised the same solution might apply so epoxied the chip on the end of some telephone line in a 22mm clamp and it works a treat. Cable and chip fit neatly into the screw-hole, flood with epoxy and done. The pipe it fits is 21.5mm so tighter than a duck's rear end...

As said, a tight fit to a twinwall radiator feed pipe, and a complete swine to get back off even with pliers, but no broken wires or oopsies to contend with, and so much faster to fit.
For those looking to measure metal pipe temperatures, possibly an unusual if fiddly solution, but no need of tie-wraps in the latter case...

Not so much a MySensors build as an example of how even the most basic information can inform changes for the better, in this case space heating.

The system here is fairly basic, an array of DS18B20s, some ultrasonic tank probes and a gas reed sensor, temperature is updated every 5 minutes, the gas updates every 0.05m3...
With winters here down to -20, the first priority last year was insulation, and even though a modern house, the gas bills essentially halved over the year, effectively funding not only the insulation, but replacement axial radiator valves and thermostat heads (Heimeier) to replace the typical arrangement of unknown origin, with spare... But now the MySensors impact..
This autumn's attention turned to the central heating unit, a modern combi unit of good manufacture, installed by a 'certified' heating engineer, but aside what little I knew about condensation boilers and the steep learning curve that followed, I was bemused by the return from the radiator loop almost burning my finger within 10 minutes of the system being fired up. This did not make sense for what I understood of a condensing boilers, which compelled a look inside for the first time, the manual and some googling.

The boiler is a 25kW combi with minimum output 7.6kW, the radiators account for ca 13kW at Delta 60 set for 15c drop (previously set ca 20c drop), settings since day one were 65c and the pump was set at max output of 3, last year's -20 resulted in 13.5m3/day gas consumed, not crazy by historical records, but hmmm.
So now comes tinkering with data from MySensors via Domoticz to inform...
Currently the boiler is set at 55c, the pump is on Low (40 v 84w), but the results are surprising - Slower rising temperature when ON, 42 minutes v 25, but gas use dropped from 0.75 to 0.6m3, but here's the kicker from that longer heating time, not only less energy used per cycle, but longer and thereby fewer cycles per day. Current evaluations are between 15 and 20% savings, so thank you to all the MySensors community and contributors..

Surprised I'm not bald will all the hair pulling and failed attempts to get there but after a year it is finally working...
The task was simple enough, to measure fluid depth in two tanks, one a sewage holding tank, the other a bulk water tank. Just figuring out which method worked with which board was an exercise in frustration, but the JSN-SR04-2.0 turned out the only one of the two I could get to reliably work.

Despite the industrial look, these waterproof light switch enclosures proved ideal, as the batteries in holders fitted beneath the clear plastic. A little hacking out of the switch 'fingers' with a Dremel gives plenty of space in the base area.
Battery holders are held in plastic conduit which are hot glued to the back of the box poking through the front section aperture.

The top case is a 3v3 WhisperNode with onboard RTC and RFM69, and tucked under the spaghetti in the top left back corner is a level converter. The RTC wakens the Node every hour to initiate readings, and despite a few hiccups seems to be reliable. The WhisperNode is allegedly capable of draining the 2 AA cells down to 0.9v, time will tell...

The lower box holds the 5v ProMini, a small latching relay, and the ultrasonic board, the button type ultrasonic (like parking sensor) is mounted on the end of a 3/4" collar to 1/2" galvanised steel tube drilled centrally through the roof of the 1.34m x 1.67m tank area.

Connection between the cases is via Cat5e in 16mm conduit, 2 cores for I2C, 3 cores for relay control and 3.3v power, 2 cores for 5v and ground to the level converter.

Despite worries over echoes in the resulting space, the tank was emptied last night, and the reading is coming in with the occasional glitch at 1620mm depth from the head, which I believe has a cone angle of 45 degrees.
The Node control of a Relay by On/Off pins to Mosfets may seem wasteful, but I had them anyway. The 5ms on/off of this small latching signal relay boots up the ProMini and seems reliable.
Still to incorporate a WDT/Reset on the 5v as it periodically hangs, and a time limiter on the Node to complete the task, but glad it is all all working semi-reliably, even if some of the programming side I still don't understand...
The 5v tests for 2 consecutive identical readings, the 3.3v tests that it fits within acceptable range, and if not calls for a further reading.

Once delivery of a second identical board from China is done, the water tank should be a lot easier. This one is the more important, as ran out of water previously due to corrosion of the level probes in the tank (3 core cable and short bolts) which stopped the borehole pump topping up the tank, and the hidrofor hit it's cut-off electrode. The level monitoring will give early warning to go investigate long before the bulk tank is 'empty'...

Postscript 12/7/18 - Water tank worked flawlessly from first deployment, but led to concerns over dropping battery voltage.. The problem appeared to lie with the Master sinking power through the I2C lines, but a routine to null the SDA/SCL lines prior to sleeping seems to have halted the decay.
One of the unexpected results of the Sewage Tank deployment was detecting a dramatic rise in level during a heavy storm (85mm in 24 hours) initially thought to be ground water intrusion.
Excavation to the incoming pipe connection to the tank found a round pipe in a square hole (not exactly an unexpected building practice here, now packed out and sealed.
Losing 30% of storage capacity would otherwise never have been detected, so it the deployment has already paid for itself handsomely...

@pepson This reminds of that famous quotation "Any ship can be a Minesweeper..."
"Once...."

@neverdie Would this work ?

@sundberg84 Yeah, this brings back memories, particularly of quite a few hangovers.
I used 3 and four wide fireclay pipes for bottle storage, they were used for ducts back in the day before plastics took over, cable went optic fibre. I noticed recently here they are back in stock in stores as....yep...wine storage racks.... but wacko pricing relatively...
The beauty of the fireclay was it's slow temperature and humidity change, and this formed the bulk of the thermal mass in the cellar I made below the floor.
I used a 150mm glazed ceramic drainage pipe dug in under the garden as a loop (rope caulked joints - anybody remember them), from memory down about 1.5m, both avoiding frosts and baking sun, don't think the temperature varied over a degree all year round, the ground acting as a massive heatsink which maintained a constant temperature all year round.
Only when the hatch was opened did the temperature jump, a small fan kicked in when the hatch was closed and ran for 30 minutes, a second contact switched on the lights and shut them off, long before LEDs were so prevalent, old reliable (until you were depending on them) incandescent bulbs.
That was it really.
Biggest problem I found was humidity in the early days, probably the fresh construction...

@tbowmo Hah, you were lucky, I finally upgraded from the monochrome to colour...

@sundberg84 Easy, one is disconnected... At 90 degrees?

Finally the round-tuit UPS got built after the last power cut clobbered the Controller/Gateway system, lesson learned...
Meanwell AD-55A, 7.2Ah Acid gel battery, two usb 5v buck converters, a spare socket for raw volts, and a 15 euro IP66 box from the local shops.. Some drilling and filing to the lid, couple of brackets, spare bolts, banding, soldering and hot glue...
A bit bulky, but disappears in a void under the stairs, two tiny drill holes let the buck converter leds shine threw...
No monitoring as yet, but sailed through a power cut this morning and the Pi didn't skip a beat.. First up is the Pi's RTC then can put the cover back on the Controller...

First of the winter projects done, just the programming to finish and replacement temperature chips to get (broke the legs off both DS18B20s through clumsiness).
With mains/battery backup and RTC, it will record boiler start/stop and run times as well as feed/return temperatures, and as an aside the inevitable power cuts which plague this part of the world.
The MCU plugs into a socketed backplane hot-glued to the back of the box should removal prove necessary, but quite pleased it is sturdy and all fitted into a slim 25mm deep standard (cheap) box.

@biffhero The Gateway doesn't hand out Node IDs the Controller does unless you define it at the Node. Your Controller set the Node ID to 1 as it was an available number, the 5 is the Child ID you assigned.
My own preference is to assign the Node ID in the sketch and label the sketch with that Node ID and increment the version numbers in both to make it easier to track which one has been programmed at the Node. It also saves on figuring out which Node ID has been assigned by the Controller. YMMV...

@NeverDie said in Coronavirus (way, way, off topic):

I'm not sure how much the hospitals can actually do that makes a difference.

Specialist ICUs can save some of those who are develop viral pneumonia, the reality is that some will die but there is no telling which is which until they succumb. The dilemma is that once ICUs are overloaded the fatality rate climbs due to prioritisation, so the trick is to avoid overwhelming the facilities or accept a higher death rate than may otherwise be the case.

The easiest way to look at this much is as a flu outbreak, but with the added feature of 10 times the infectivity. For flu there are shots which can provide greater but not complete protection for the more prone, an annual mutation which the manufacturers refine on each cycle.
In the COVID case there is as yet no vaccine nor natural immunity, but crucially it is infectivity which is the danger as it presents a deluge of critical cases rather than spread over say many months.
Social distancing and isolation measures can slow the rapid spread, testing vigorously and isolating as in the Singapore and Korean etc models is another successful technique.

The rest is a political decision...
This post I thought entirely apt...

@NeverDie It's only apocalyptic because politicians made it so or played it down, the nuts claiming it's no worse than flu, or a scam by money manipulators, or Chinese conspiracy, or would damage the economy, only helped obscure the danger to human life by confused messaging.
Odds of dying in ICU is averaging 17% from the figures I've seen, 27,000 dead so far, no plans to join that number but acutely aware I'm high risk, hence isolated...
DNR is normal once ICUs are overloaded, a shot of morphine is all they can do to ease the passing.

For now hunker down and take reasonable precautions, even from our own family members if symptoms show. Until governments are forced to take this seriously and adopt the WHO measures, there is very little upside until you survive it...
Best of luck over there.

@NeverDie We have been teetering on global recession/depression since 2008 because the underlying problem was never addressed, we just stuck a band-aid on it and carried on with the same "religion". The MMT model is now peeking out amid the UK crisis, and the finance circus are up in arms seeing their QE milk-cow taken away. For the US there are multiple times that resistance and greater lobbying power but that's a whole other issue..

The problem with your earlier point is what value is placed on a human life, and as both preceding posts made clear the statistical prevalence of older sicker people masks the fact that this virus takes out the young and fit also.
Without mitigation and ultimately intervention those numbers will escalate dramatically, and you're going to need multiple field hospitals built by the army in record time to cope. It is THAT serious.

As of this morning the US exceeded China's infections (who tested rigorously and universally v the US scenario) the wider the spread of the virus the greater the number of young and middle-aged who will die, it really is THAT simple.
As an aside, a 4,000 bed field ICU is almost completed in London just as ALL hospitals are at breaking point, but with it's high population it will still be too little for the tsunami which hits over the next 10 days.
Time was up 6 weeks ago....

@NeverDie As @scalz aptly quoted, "when there is fire, you shouldn't look at the water bill", unfortunately many of our politicians obsess over little else.
Frequently ignored on stats relating to age range of fatalities is the realities faced where COVID overwhelms, such as Italy. Those >60 are more likely to have medical complications which increase chances of pneumonia. When numbers attending hospital exceed resources, prioritising WHO gets ventilation kicks in. Over 60s are not priority but are given "assistance" to suffer less, hence inflating fatalities in that age range. A dreadful but necessary choice for doctors typical of a war zone.
China went on a war footing rapidly, field hospitals, roving screening, contact tracing, they wrote the book. Korea and Singapore refined the techniques successfully, look at their numbers and condition now...

It is too early to assess the long term damage to health for survivors, but lung damage is fully expected, hence the desperate search for drugs which can have beneficial effect BEFORE infection becomes destructive.

Finally, the front line as @scalz highlighted. It is crucial medics etc are given all the PPE and kit they need, without it their numbers will deplete, and fatalities will increase... No healthcare system can handle this, again highlighting the importance of strategy deployed by Singapore/Korea etc, screen, test, trace, isolate.

Watch London in the next 10 days for a textbook example of bean-counter mentality on the health of a populace, it will eclipse Lombardy...

@Joost My only thought on the RTC is separation of the timing aspect allowing the processor to go deep-sleep forever until Interrupt. I have one set up to hourly scan my water tank, but I can press a button in parallel with the interrupt to ground for ad-hoc update.

@hakha4 Domoticz flaked on update with my Buster on the Pi Controller, updated Buster and all fixed.

@Joost RTC?

@NeverDie There do appear to be conflicting reports of test results, but what is not clear in some cases is what the test actually was.
What IS however very clear is that different strategies of identification, distancing, isolating, quarantine are having various profoundly differing impacts on the spread of the virus, but doing nothing is catastrophic.
A collaborative article drawing together various aspects of this I'll attach here, a long but illuminating read, and we all have plenty of time of late... The projections for the US were eye-popping, even if the orange faced idiot thinks you'll all be at Easter church services..
https://medium.com/@tomaspueyo/coronavirus-the-hammer-and-the-dance-be9337092b56

@NeverDie said in Coronavirus (way, way, off topic):

They should have interviewed one

Not sure what US media is like, but in the UK it is expert and eminent virologists such as Pierce Morgan, Nigel Farage and Boris Johnson's father they select to interview....

Considering the speed at which this has unfolded the knowledge gleaned has been remarkable, much more to come I suspect.

UK now has finally gone into lockdown and I believe the US, but there is still considerable disinformation circulating which is not helping, such as Dan Patrick's idiocy on Fox News, reported in the UK along the lines of "WTF... and we thought Boris Hohnson was mad".
Will leave you with this reality check from Ireland, where numbers are still mercifully low... https://www.independent.ie/irish-news/stay-indoors-im-young-sporty-and-fit-i-never-would-have-thought-id-catch-coronavirus-39070693.html
Good luck to all, stay safe...