No C Wire Options
Compare no-C-wire smart thermostats by power method: included adapters and extenders, battery power, and the line-voltage systems to rule out.
MoesHouse ZHT S03 Smart Thermostat (Battery Powered, Weekly Programmable)
Smart WiFi Temperature Humidity Monitoring Switch Advanced remote control via iOS/Android apps
Smart Wifi Temperature and Humidity Sensor Advanced wireless transmission
Sonoff TRVZB Smart Thermostatic Radiator Valve
Smart WiFi Thermostat with LCD Touch Screen Remote control via mobile app
Smart WiFi Heating Knob Thermostat WiFi connectivity for remote control
Smart WiFi Thermostat Temperature Controller WiFi Smart Control for remote adjustment