Cost-sensitive way to maintain a 220C temperature
It is quite simple to do it without any digital electronics (MCU with ADC) or analog comparators (thermistor) with triac.

You can use only a component: a fixed temperature thermostat. The circuit becomes very simple and reliable. Just connect it in series with the heating resistor. Also there is no need for auxiliary power supplies. Just make sure the switch is rated at a higher than the required amperage.