Once constructed this kit can be used to switch on 230v appliances such as a heater heatpipes or similar when a set temperature is undershot a kty 81 220 temperature sensor thermistor determines temperature and the limits are set by the user via a trimpot a separate trimpot can be used to maintain temperature hysteresisfour leds indicate the switching status mains on green probe breakprobe short circuit red and relay on yellow the integrated probe monitoring notices short circui