I have been told by my local NC dealer that the TCONT900 thermostat does not work with the XR15 (non communicating) and XC80 (communicating) blower/furnace combo unit 4CXCD061CC3. So am looking for Trane documentation to clarify if that is indeed the case and to find out if anyone selected the XL900 for use with the XR15/XC80. Otherwise planning to use the TCONT803.