Stelpro releases the first Z-Wave Plus Line-Voltage thermostat: the STZW402+ Stelpro Ki Thermostat

Good news everyone!

SmartThings has finally integrated the latest and greatest Stelpro Ki Z-Wave thermostat device handler into its platform.

That means you no longer need to create a custom device handler based on the code found on github.

As for the Samsung Connect compatibility, I was told that it should work also.
However, at the time of this announce, I wasn’t able to confirm that claim.

The zigbee versions of the Stelpro thermostats should also be integrated soon, stay tuned!

The new Smart things approved device handler was not working with my Alexa. The app reports that the device is not responding, but it will eventually change the settings.

Yep, same with my Alexa device. Seems like something is still not reporting right.

I sent a notification to SmartThings about this.
I will update you when I hear back from them.

Greetings…

We have a 16,000 sqft plant with ceiling 120v radiant heaters. They run with simple 120v Home Depot thermostats. I was thinking of converting them all to the STZW402+ Stelpro Ki Thermostat as they are pretty cheap and I would also set the shop up with Smarttings to run it all.

Technically this should work?

Francis :slight_smile:

Hi @PrometheusXex,

The answer to this question is in two parts:

  • Electrical compatibility
  • Temperature control accuracy

Regarding the electrical compatibility, as long as the 120V radiant heaters power rating is within the Ki Thermostat limits, that should work, electrically speaking

Regarding the temperature control accuracy, the Ki thermostat has not been designed to control such devices. The Ki thermostat is designed to control baseboard heaters and convectors in a regular room, not in a 16,000 sqft plant.

This specific use case was obviously not tested.

My personal feeling is that the thermostat would turn the heat on, but I have no idea how it would control the temperature inside the plant.

It might work well as it might lack in accuracy, hard to tell.

It’s up to you to go for it or not.

J-F

Thanks for the reply.

I have multiple heaters spaced evenly throughout the shop and the Home Depot 120v thermostat has been running for the past 18 years… so it should be OK from a thermostat point of view.

FYI the type of radiant heater we use are gas heaters and the 120v is just to run the small built-in circulation fan motor. There’s minimal electrical load in the thermostat.

the 120v is just to run the small built-in circulation fan motor.

That’s the part that worries me.
The Ki Thermostat is not intended to control an inductive load.
It needs to be installed serially with a resistive load.

Could you tell me what thermostat was used for the past 18 years?

They are literally just those thermostats used for baseboard heaters.

https://www.homedepot.ca/en/home/p.manual-2-wire-electric-baseboard-heat-thermostat.1000429052.html

It acts more like a like switch when heat needs to turn on.

No offense to stelpro and buying one…(I have two and love them) but for what you are doing you might be better off with a simple zwave outlet and wire the fan to that. Get yourself some remote temp sensors and fire the fans on/off based on temp or even other factors. Just a thought…

For another question…my StelPros report in every minute with status of the following:

Parse returned [[value:65.0, unit:F, name:temperature]]
Temperature 65.0
Multilevel report: 1

Is there a way to decrease that?

@PrometheusXex,

The thermostat you were using is a bi-metalic, non electronic thermostat.
This type of thermostat does not have a minimum required load like the electronic line-voltage thermostat does.

So, it all depends on the radient heaters.
But as I described earlier, I’m afraid that the small built-in circulation fan motor is not compatible with the thermostat.

Personnaly, I don’t think the Ki thermostat is the right one for your application.

Hi @Jrfarrar,

No, the thermostat is configured to report its temperature every minute.

The only way to change it would be for you to modify the device handler and change the report intervals in the configuration reporting commands.

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So where do I find this device handler? I have both the “original” Hub and the new Smartthings Wifi, and there are no Stelpro devices in either place. The I put the Stelpro ZW thermostat in inclusion mode, it is not found. Thanks for the help.

Hi @BroncoCountry,

That’s weird.
You should have nothing to do in order to have the thermostat detected by the hub.
On my setup, I have no longer a custom Stelpro device handler from github.
Instead, my SmartThings hub detects it right away.

Could you give us more details on your setup?

@dkirker, please advise.

J-F

Hi- I have the new Samsung SmartThings WiFi hub https://www.samsung.com/us/smart-home/smartthings-wifi/all-smartthings-wifi/s/multi_packs/_/n-10+11+hv2gy+zq2mb/ (not the new SmartThings Hub).

The new app also does not list the Stelpro. I put thermostats into menu “1” then “on” and flashing radar sign. Nothing detected.

Thanks,

Shawn

Hi again,

The app will not let you choose the Stelpro thermostat.
However, it should detect it when you put your hub in pairing mode.

As for the hub you are using, I have not tested it myself.
But I assume it is Z-Wave compatible…?

Do you see its LED blink when you put your hub in pairing mode?

Check these things out, otherwise I would recommend reaching for the SmartThings tech support.

Hi -

I have two Stelpro STZW402 thermostats, each controlling two Stelpro baseboard heaters. Right now, in the Smartthings app, both are reporting this incessant “idle>heating>idle” activity, with as many as five or six fluctuations each minute, all day.

Take a look at the screenshot and you’ll see.

Does anyone have any idea what could be going on?

Dave

Hi @davempls,

This reflects the actual heating operation. The baseboard are controlled on a 15 seconds duty cycle.
That is why you see such behavior.

Now, if this is bothering you, you may turn off these notifications by going into the thermostat settings in the SmartThings app and put the “Do you want a detailed operating state notification?” switch to “No”.

Do this for both of your thermostats in the mobile app.

J-F

Wow, thanks. I wouldn’t have guessed that the thermostat would be making such frequent checks/changes to the operation of the heater. Good to know!