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.
Google CE911542 Smart Learning Thermostat with Temperature Sensor
Programmable Smart Outlet Thermostat White WiFi-enabled programmable outlet thermostat
Honeywell Home X7S Smart Programmable Wi-Fi Thermostat with Humidity Monitoring