I am looking for a ST-compatible temperature sensor with a range that extends to (or beyond) 225°F/108°C. My intended use scenario is to attach this to, and measure the temperature of, a steam pipe, so it would have to be capable of measuring contact temperature rather than (or in addition to) ambient temperature.
If I am unable to find something off-the-shelf, is this something that could be made relatively easily?
Fibaro FGK-101 and DS18B20 - maybe not reliable - tried to get my two talking again for another smoke but failed . I did not try very hard.
As @ero4444 mentions, this is almost always done by using a simple probe sensor designed for those temperature ranges and cabling it to the radio device so that the radio itself can be some distance from the heat. This results in a much less expensive setup, more appropriate for a home automation budget.
So in your search, look for devices that can accept input from a separate probe and you should find more possible matches. 
There are at least three different devices that people have previously used. See the following thread (the topic title is a clickable link)
Thanks @ero4444, that looks like a definite possibility. Why do you say it might not be reliable? Reliability is important in my scenario as I’m contemplating using it to control/limit my home heating - I’d factor in a redundancy so my pipes wouldn’t freeze if it were to malfunction while I was away, but I’d like to be able to rely on it.
BTW, qubino does offer a $50 zwave temperature monitoring micro that comes with its own probe. The micro gets wired into the mains.
if your purpose is important/critical, then it deserves to be hardwired. A pipe-strapped low limit control device seems appropriate if freeze is a risk - I typically call that “aquastat” . They are made in fixed- and adjustable-setpoint devices. Search for aquastat will turn up many options.
I call the Fibaro assy unreliable because after re-inserting battery to 2 previous-working-devices, then they did not easily restart logging, nor easily re-pair, at my last 1-2 attempts. That could be ST aging something out for inactivity, my bad technique, or anything. The end result was no data, so I do not “rely” on them - not to my standard for control of HVAC.
For monitoring-only, with really slow response, I would just use a door-contact with temperature, strap it to the pipe and insulate over it. Plenty of those laying around and they just work. I suppose it will melt >160F but it would be fun to find out.
I have had very good reliability using DS18B20 connected to an Fibaro FGK-101 and also multiple DS18B20s connected to the Fibaro Universal Binary sensor FGBS-001. I am using the FGK-101 to monitor a freezer and the FGBS-001 to monitor a fish pond at home and a swimming pool at another location.
I would question the range though. The DS18B20 is spec’d for -55C to +125C. Is this enough? I agree with ero4444 on only using for monitoring though. You have to ask yourself what happens if it does go wrong.
Thanks, @JDRoberts, for the information - it is very helpful. The Qubino may be a perfect solution - I like that it runs off line power rather than battery, too.
@ero4444 It’s not too critical - at least at this point. My plans were to put the sensor on the end of my steam main and do some logging to find out how long they took to vent and then how long it took from my mains being filled to my radiators warming up. After I was done with my research and logging, I was thinking I would play around a little with some control logic to see if I could arrive at something more efficient than my Ecobee. But, I would not do that without a redundancy or backup (eg. if heat dropped to XX° then everything would revert back to Ecobee’s control).
@siwilson Yes, I think the range would be enough. Hottest it would get is steam at about 1 psi which is about 215°F.
Thanks, everybody, for your input and ideas.