Hello,
I recently emailed hubitat support regarding a bug with the zen thermostat driver. Hubitat team fully acknowledged the bug, but there has been no update since.
It appears others are having the same issue, see middle of thread written by user bertabcd1234..
Can we please get an update on this issue?
That's me! 
I don't think there's anything Hubitat can do about this. I think it's the way the thermostat internally rounds and reports values (I would say that it could be a C to F conversion, but these values don't even make sense for that). It acts the same on SmartThings, the only other platform I was able to get this thermostat working on.
Despite these oddities in reporting (it was stable once it reported a value--it wouldn't randomly report a setpoint change if it didn't change, for example), the values didn't actually cause problems for me (though I have moved to another thermostat for different reasons). If that's happening to you, perhaps you could share the automation and someone could suggest a solution.
Zen support said reach out to Hubitat support. Zen support said their device does not have an issue.
I'm using the out of the box thermostat scheduler app based on Mode. Instead of setting a integer, it sets a near value with random decimal attached. It's very strange. Hubitat support did acknowledge the bug, so.... Which thermostat are using?
Yeah, that's the device. You tell it to set an integer, then it returns a number with a decimal point that vaguely resembles your integer. I never used Thermostat Scheduler (I have a custom app that sets it to an "away" setpoint when I leave, then I manually turn it up/down if/when I want to). Does that cause problems with Thermostat Scheduler? I don't think it should--once Thermostat Scheduler sets the setpoint, I don' think it keeps checking and retrying. I'd be curious what Support said. I'm not really sure it's a "bug," just what the device reports and the driver reports in turn.
I switched to a Powerley Thermostat provided by my utility company, but I don't think they're generally available. My issues with the Zen were just odd display issues the above caused, plus eventual loss of ability to turn on the fan (but not off) remotely.
Hubitat Support - will you please fix this issue?
Thanks. The existing case number is 15178.
You can certainly wait for Hubitat Support, but I'd be curious what problems you have. Setting it to 60 and seeing it actually get set to something like 59.8 or 60.2 is just what I've seen this device do on both Hubitat and ST. Does Zen have a platform they recommend where they know this doesn't happen? I imagine it's the result of some C to F conversion, though again the values don't always make sense for that.
The thermostat itself is will still physically report the value you set it to--I think this is just it being a bit too specific over Zigbee. This shouldn't cause any problems, just maybe some annoyances if you have apps or rules that depend on a specific integer. I've always been able to work around this. Do you notice any specific problems here? If so, I think you'll have a lot better luck trying to work around those than getting Zen (and I really think this is them) to change anything. But again, in my experience, the thermostat is set correctly, reporting is very close (and consistent), and it did not cause actual problems.
There's a similar issue with the Honeywell T6 Pro z-wave thermostat.
If the temperature reporting resolution is 0.5 degrees F, then it sends values to Hubitat that are slight off (again, I assume its a consequence of some Centrigrade to Fahrenheit calculation). Again, doesn't affect thermostat function.
Off topic - is the Powerely thermostat OEMed by Zen - just looks a lot like it from the photos I've seen.
And does anyone really believe that the thermal sensor in any thermostat is accurate to anything better than .5 degrees f?
I don't think so, or least I didn't see that anywhere. They do look similar in photos, but in real life they're pretty different (the Powerley actually has a button: labeled "mode" but confusingly also necessary to press to adjust the setpoint), not perfectly flat and square like the Zen, and has a square- instead of dot-based display matrix. But it's still probably the closest Z-Wave thermostat in terms of appearance.
Probably not, but the real issue here is that you (apparently) can't configure the resolution of reporting. I don't want this; it just does (or did) it. 
The problem is for example when I set the heat to 68, it then sets to 68.3 or similar value. Same for cooling setpoints, likewise for the target setpoint. It's broken, we expect it to set the exact value. Is this a hubitat issue or a zen issue?
I can force the setpoints events to an integer when the temp scale is F if that helps in anyway.
That would help Mike. Go for it, I'll work with you to provide feedback.
To be clear, that would change only what Hubitat reports. The thermostat will still be 68.3 or whatever, and Hubitat might just round the reporting to 68.
This is actually kind of nice to know sometimes--I think by default it needs a 1.5 degree difference to turn on the heat, so this specificity plus equal specificity in current temperature reporting allows you to know when that might happen. My new thermostat only reports whole degrees and makes things like Dashboard tiles a bit easier to use. But again, neither way should cause a problem. The thermostat gets set to whatever it lets you set it to, and the Zen is just picky about what it lets you set it to, whether physically or via Hubitat. It's just that it reports these more specifically over Zigbee than physically, where the display is limited to whole degrees F.
Can we make it optional?
The more I read through this thread, the more I'm realizing this is an issue with Zen. You would think they would fix this issue with a firmware update?
Is anyone using a zwave or zigbee thermostat that does not have this issue? I'm thinking about buying something different.
The Honeywell T6 Z-wave pro has this issue if the temperature reporting resolution is set to 0.5 degrees Fahrenheit. It doesn't have the issue when the reporting resolution is 1 degree Fahrenheit.
I had a centralite pearl before this, I much prefer this little quirk compared to the issues I had with the pearl.
Since I don't believe in the accuracy of temp sensors, I figure it is more about what setpoint am I comfortable at, not what temperature.
Download the Hubitat app
