The actuator generates the necessary electrical energy for operation by means of a thermoelectric generator (TEG), which gains electrical energy from the temperature difference between radiator flow and room temperature. During the heating season, excess energy is accumulated in the internal storage for operation in transition periods and summer. The energy balance of the actuator is designed to allow operation through 365 days per year when used in typical radiator heating installations.
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Energy storage bit ES
By means of the status bit "Energy Storage" (ES; DB0.5), the device indicates that more energy is being used over the long-term during operation than has been generated, i.e. the storeage has lost its charge. The remaining energy in the storage is approx. 25% now, which is why the drive continues to function fully while it signals a negative energy balance to the user. It is urgently recommended to check the ES bit regularly or at maintenance intervals in order to detect a discharge of the storage and to prevent its progress through suitable measures (e.g. regular, short heating intervals outside of the standard operating times). If the energy storage device continues to discharge and its voltage falls below a certain limit, the drive automatically switches to forced heating.
Forced heating
Forced heating is defined as the state that the actuator enters when it can no longer maintain normal operation as a result of its internal energy storage being discharged. Instead, it takes a protective position in heating mode in order to avoid possible heating circuit damages from freeze. To do this, the drive opens the valve to 50% or retains the previously set value if it has exceeded 50%. The drive then deactivates itself in a state of minimal energy consumption: radio and motor activities are not carried out, and local inputs are also ignored. It remains in this state until the memory is recharged to a sufficient level by the thermoelectric generator.
In this operating mode, the unit cannot be addressed via radio or local input, and temperature fluctuations in the room will likely occur. As soon as sufficient electrical energy is available, the actuator ends the forced heating and resumes normal operation. General reloading of the storage by means of forced heating requires full heating operation over several days, which is why this state should must be avoided in advance by taking suitable measures (monitoring the ES bit). Operation in unheated or insufficiently heated rooms is to be avoided.