The lowest power consumption is around 1200w for the whole setup. It gets closer to 1600w when running at full capacity. With the advancements in firmware, you might be able to push the lower bound of consumption down. I would say the setup is about as small scale as it gets for heating domestic hot water though. I'll make a post about the interations of the maple sap heater and ground loop bottom heater for the mini greenhouse cold frame.