Can anyone suggest a good solution for this, please?
I need to put a temperature probe into a very hard to access location (a roof void). I never want to go into this location again, so I want a fit-and-forget device. It is only a couple of meters from an accessible location, so I can run wires. Ideas I have considered:
A Type-K thermocouple on the end or a wire, leading back to a device that sends signal to Habitat. Ideally, this is mains powered. I would like this, as it would then allow be to use this probe solution elsewhere.
Use a Zigbee temperature monitor, like the Sonoff one, and run wires to the battery terminals. Then fit the battery remotely. Or, better still, use an old phone charger (suitably down voltaged) to power it.
Similar to 2, but use something like a Ultralife UHE-ER34615-H bobbin cell - D-size Lithium Thionyl Chloride battery 3.6V 19000mAh to power the zigbee device for a very long time. Would this work?
Any other suggestions? I basically never want to have to access it or change a battery.
What I'd like to do is have several temperature probes that I can place in different parts of buildings, in walls, etc, and have Habitat monitor them and record the data. I remember reading some months back about a way to create temperature maps, and record data. I now can't find it, but recall it involved installing something that looked complicated!
Am I missing something that's already out there, but I haven't found?
I have done this for several zigbee/zwave sensors. Bought a bunch of 3.3V power supplies on eBay, and hardwired them. They’ve been good for years now - some as long as 6 years.
It's a good suggestion. Moderately pricey, so maybe okay for this first instance, but probably wouldn't want to roll out multiple devices. Ten years is a good run.
IMHO I would wire these locations with Type K thermocouples for long term reliability. The only way I am aware of to do is to use an Arduino with Hubitat Hubduino software/driver.
I realize it will be more work to get started, but will have superior reliability. You could even run dual thermocouples to each location and use one as a backup in case the device was damaged by some external occurrence (falling limb , hail, etc)
In addition, a thermocouple does not have any temperature limits in such a location. They will easily withstand the hottest hot and the coolest cold.
Just a note, the above discussions focus on battery life, not device failure. Folks have posted both good and bad results putting a Z-Wave or Zigbee device outdoors. Although I'm not sure what type of environment a roof void is.
I used zooz 4 in 1 sensors for my attic and basement with hard-wired for power. Been working for a few years with no issue. I just wanted to monitor the temp but throw on humidity and lux as a bonus.
This confirms what I suspect! I like the idea of just a Type K thermocouple (or a few of them) in the inaccessible area. Almost nothing to go wrong there. The things that might need attention - the electronics and power source - can be located in an accessible place.
The question is, what's the best strategy in terms of effort/expertise required!
The next response, re nodemcu, I like... but it would be a learning curve!
Researching this a bit, it sounds ideal. Cheap to roll out, I could install loads of them. But whilst I'm very practical, good with soldering, fairly technical... I have not dipped my toe in the programming modules water.
Honestly, how much of a learning curve is it? I appreciate that once mastered, I could do all sorts of things, but I don't really want to get into heavy programming. I would rather pay a little bit more to buy a module that is ready to connect to Hubitat, and have a probe wired to it. Is there an half way house like that?
Yes, I could crimp or solder no problem. They look pretty good - the relay switches also have thermocouple inputs, yes? So it just sends data back to Hubitat? Sounds good, but they are moderately pricey. I'm in UK, and they're £25 a piece. Given that I would like to roll out maybe half a dozen, it adds up.
The node MCU route is more technical but you would not be blazing new territory.
I suggest you investigate the combination of:
Hubduino Firmware
NodeMCU
T/C to SPI board Be sure you get a board with the components circled. They are for filtering and protection of the MAX31855. Without them the MAX31855 is more at risk from various induced voltage spikes.
I don't know if Hubduino supports the MAX31855 so you should contact @ogiewon (the Hubduino author) to see if Hubduino will "read" the MAX31855. If so all the software is available and all you have to do is wire the thermocouples, Max31855 board and NodeMCU.
PS I've used the MAX31855 with a regular Arduino and have had good luck.
If you have any questions regarding the Thermocouple wiring please let me know.
Thank you for all the input. I think I've made myself some homework! Whilst more work, I know deep down that learning to do it with the basic components is the right way to go.
I'll do some research and shopping, and come back as and when I get stuck.
