WAT12 also provides the sensors with a throughput for optional heating power. The heating power connection requires an extra pair of wires. Since the heating elements in the shafts of WAA151 and WAV151 typically consume some 500 mA, the heating power is most conveniently supplied from a local power source. A thermostat switch is available for automatic connection of the heating power in temperatures below +4 °C (39.2 °F).
The optional heating power requirement is 20 V AC or V DC, and 500 mA for both WAV151 and WAA151. The sensors can be connected in series, when a 40 V power supply providing 500 mA is required. Alternatively, the sensors can be connected in parallel, when a 20 V power supply providing 1 A is required