Stonehedge-
Ideally there'd be something both wireless and battery powered that could do it all (like the Tempe but with Humidity and Pressure) but I don't want to be changing batteries in things all the time - and non-rechargeable batteries aren't great for the environment.
I did wonder about using a bunch of Pi Zero powered using PoE but since there's no ethernet wiring in the walls of the flat that's not a goer. If I'm running cables then they may as well be a big passive 1-wire loop.
Even those IoT4.eu sensors need power and have a cable running to the thermocouple so there's some form of wiring already. The main reason for not using them is that I generally want two temperature sensors in each room, one for air temp and one for radiator pipe temp. Paying another EUR29 just for an extra temp sensor is a bit much.
If I was able to splice in a second DS18B20 of my own into the wire and the system was capable of dealing with this then the price (including the humidity sensor) would actually be quite reasonable.
The electronics and backend coding bits don't bother me, one of the previous projects was a RPi that would scrape the TFL live bus website and display the time and when the next local bus was due outside our house (it only goes once every half an hour). The Pi ZeroSeg module needed to be soldered together, which is less fun with lead-free
soddersolder. One of the buttons would make it cycle through the buses due at the end of the road (Putney Hill), the other button would make it display a silly message for my daughter.
(I think I used a PiZero for that hence the separate Wifi dongle. Using a PiZeroW would mean I can get rid of that bit.)
I was going to place it in the hall by the front door where the existing alarm keypad is (and I can use the existing alarm cables to provide the 5V USB power for the Pi).
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Greenbank
Interesting but moneygun.gif
That'd be close to 300EUR for what I want to do (and not much cheaper if I didn't worry about humidity). I like the idea of monitoring barometric pressure too, will add one of those to my list for the outside monitor.
Humidity sensors aside, I was planning on spending about 30EUR on the lot (already have a spare RPi to act as the 1-wire host). A bunch of DS18B20's, a 100m reel of 3 core cable, some heatshrink, zipties and a lot of swearing. Also means I don't use up a power socket or two in each room I want to monitor anything in. For now I was just going to isolate and remove the existing alarm system (we've long since disabled it) as it has a bunch of 3-core cables going to various most corners of the flat.
If we ever get this flat rewired then apart from Cat 6 everywhere I'd also spec out a proper 1-wire architecture at the same time, that would simplify things a lot if the cables were already in the walls all going back to a central point.