How the anti-freeze temperature controller works
Until the desired ambient temperature is obtained, the relay contact is in position 11-12 (red LED is on) and the heating device is turned on. When the set temperature is reached, the contact switches to position 10-11 and the heating device is turned off (red LED goes out).
A temperature drop by the hysteresis value will switch the heating device on again (contacts 11-12 closed) until the set temperature is reached.
