I.e. I’m looking for a temperature sensor that is designed to measure the temperature of the object it’s strapped or glued to. In this case, I want to monitor the temperature of some pipes under my house to see if there’s a risk of freezing. I want to measure the temperature of the copper pipe itself, not the ambient temperature.
Not sure how accurate it would be, but if you placed the temperature sensor on the bare pipe then insulated it from the outside environment it might give what you want?
It’s easy to do, but it’s not cheap.
You just get a dumb probe sensor, typically around $15. Foam insulate it on three sides and attach it with the other side touching the pipe. ( usually you attach the probe to the pipe first, then insulate over it. )
Connect it to a Z wave device That can read the temperature from the probe. There are a couple of options for this, Typically costing from $25-$65. That Gives you your smartthings integration and keeps the zwave radio away from the pipe and the insulation.
Discussion of Z wave options with probe sensors (this is a clickable link)
Discussion of attachment to the pipe
You can use DS18B20 TH Sensor with Sonoff TH
I posted a similar question on the Hubitat community several days ago. While not specific to SmartThings, the info in the post might prove useful.
Good point: you can use any radio device that communicates with smart things.
I have a slight preference for devices that are concerned about freeze danger that it run locally, since times when the power is out are the times when freeze danger is highest.
That said, while I know The Wi-Fi options don’t run locally because they require custom code, to be honest, I’m not 100% sure you can get temperature reporting from a Z wave device that runs locally with SmartThings, although I think it may be possible. Of course then the question is how do you get the notification.
So you just have to check each action to see what would actually be available even if you have the hub and router on the UPS back up. Or if you throw the ADT model into the mix.
Like I said, I’m just not sure exactly what you can get done if the power is out, you’d have to design for that. So just a thought.