i want to control electric heater (connected to electricity socket) by using WiFi smart plug. What kind of thermostat (which device) i need to connect to my 'smart network' so i can create a rule to turn plug on if temperature drops below some limit, and turn it off if temperature rises above another limit ? is it enough to do that with WiFi plug socket, amazon echo/google home and some temperature sensor (ready device, i don't want to build and connect my own RaspberryPi etc) ?
This is a dangerous idea, what happens if the internet goes down after turning the device on?
If you want a device that can be remote controlled I suggest you look for one that is a device that hosts all the features in it's self. Such devices have their own safety cut offs built in and do not rely on messages having to travel off site and back again to cause a change.