The other thread on heat pump cylinders led me to this Heat Geek video, where Mr Heat Geek seems to be having a pretty major dig at the Mixergy cylinder's suitability for heat pumps. I don't pretend to understand it all. I know that Heat Geek have recently launched their own range of heat pump cylinders. Is he claiming in this video that his cylinder is 400% more efficient than Mixergy when used with a heat pump?