Hi -

 

I upgraded my ISY-994i Pro with the new Z-Wave module, specifically to then add and use the Trane XL624 Z-WAve thermostat.  The hardware-upgrade went smoothly on the ISY, as did wiring in the thermostat and adding this Z-Wave device to my ISY controller.

 

One setting I changed on the thermostat was the Temperature Units -> I opted for "Celsius".  On the thermostat, I can now set temperatures in 0.5C units - in fact, my heating setpoint is set at 22.5 C.

 

However, the ISY Device status for this thermostat only shows me whole degrees.

And in the programming, I can similarly only make whole-degree comparisons / settings.

 

Whole-degree comparisons and settings are too coarse for my liking.  Does anyone know if this whole-degree limitation is a result of Universal Devices' code, or if it's a limitation of the Trane XL624 (may report whole-degrees only, while displaying 1/2-degree numbers)?

 

TIA!

The 2Gig CT100 also displays .5 degree increments but only reports whole degrees to the ISY. This can be verified by turning on the event viewer and watching the status messages from the thermostat. However, it's likely the ISY would only use whole numbers also.

Hi gordonp,

 

In the ISY 4.5.x firmware, the ISY does use whole numbers for heat/cold setpoints.  In the ISY 5.0.x firmware, it uses the precision specified by the device.

Thanks @andyf0 and Chris Jahn:

 

You've given me some ideas - my ISY994i is running firmware 4.5.4

And I fired up the Event Viewer, and it appears the Trane XL624 will only report whole-numbers:

Fri 11/25/2016 08:28:19 : [D2D EVENT   ] Event [ZW002_1] [CLISPH] [22] uom=4 prec=0

Wow  I happen to like half-degrees (Celsius), and I can dream about 0.1C units  I suppose a work-around might be to use Fahrenheit, but my wife and kids have simply never been exposed to this (I grew up using Fahrenheit, and consider myself fluent in both...)

 

Thanks to both of you - it seems a limitation of the thermostat.