Honeywell YTH8320ZW1007/U Z-Wave Enabled Programmable Thermostat Please refer Page 18 and 19 of User manual for troubleshooting steps Z-Wave delivered messages allows the thermostat to be added to or removed from a Z-Wave controller.Wire saver allows for use without a common wire. Intuitive adjustment for precise comfort control, easy to use touch screen display and extra large backlit display with natural language Menu Driven programming guides the user through the programming process only showing necessary information and choices on each screen Thermostat operating message feature sends a message containing the status of the HVAC equipment The YTH8320ZW1007 includes the TH8320ZW1000 thermostat plus the THP9045A1023 wiresaver module. Please refer Page 18 and 19 of User manual for troubleshooting steps This thermostat only connects to a z-wave communicating system (not Wi-Fi). Z-Wave delivered messages allows the thermostat to be added to or removed from a Z-Wave controller. The THP9045A1023 wiresaver module must be used when there is no C or common wire. A common wire is required to power the thermostat Intuitive adjustment for precise comfort control, easy to use touch screen display and extra large backlit display with natural language Menu Driven programming guides the user through the programming process only showing necessary information and choices on each screen Thermostat operating message feature sends a message containing the status of the HVAC equipment The YTH8320ZW1007 includes the TH8320ZW1000 thermostat plus the THP9045A1023 wiresaver module.The wiresaver is used when there is no common wire. A common wire is required to power the thermostat.