Energy Harvesting

The actuator generates the electrical energy for required for operation (motor, sensors, radio communication) by means of a built-in thermoelectric generator (TEG) and therefore operates maintenance-free. The TEG harvests energy from the temperature difference between the heating flow temperature and the ambient temperature (usually room temperature), which it accumulates in the internal storage. The energy balance of the actuator is designed to allow operation through 366 days per year when used in typical circulation strands with hot water supply throughout the year. An additional energy source such as a primary battery or external power supply is not required. The internal energy storage device is charged upon delivery, so that sufficient energy is available for installation. An extended lack of hot water, for example because of down times or malfunctions, inevitably leads to the internal storage being discharged, which means that permanent and normal operation of the device can no longer be guaranteed.

Device power management

The actuator allows the end user application to monitor and compute the energy status through regular measurement of the device internal parameters. Internal storage voltage STV (V) and average current generated ACG (µA) are actual measured values whereas average current consumed ACC (µA) is a computed value. The computed average current consumed value includes motor amount and direction of movement, radio data rate, radio communication frequency, and sleep current. The following two diagrams are illustrations of the energy balance from a running application.

Energy Storage

The actuator uses its status bit "Energy Storage" to indicate that its long-term operation has consumed more energy than it generated. The remaining charge level at this point is approximately 25%, which is why the device continues with full functionality while signaling a negative energy balance to the user. It is strongly recommended to regularly check the ES bit in order to recognize a discharge of the storage and to prevent its progression by suitable measures (e.g. Slow Harvesting outside of the standard operating times). If the energy storage continues to discharge and its voltage falls below a certain limit, then the device automatically goes into the state of Forced Heating. 

PORT 0 - MAC Command 0x06

If, on Port 0, a MAC command 0x06 is sent to the device, the device returns battery level information.