De Dietrich - AD 304 - modulating VivaTherm room thermostat - wired - This thermostat controls and programmes the heating and the sanitary hot water. The control adjusts the boiler output to the actual demand. 3 possible operating modes: AUTOMATIC: according to a programmable weekly schedule: the desired temperature can be set for each programmed period. PERMANENT: to guarantee a constant temperature during day mode, night mode or frost-protection mode. HOLIDAY for long absences. The start and end dates of the holiday can be programmed, as well as the desired temperature during the absence. For weather-dependent operation as a function of the outdoor temperature, the outdoor sensor (colli AD 225 or FM 46) must be connected.