As all the factors which include pump, 3-way valve, growth vessel, control device and electric powered flow and again-up heaters are contained within the indoor unit, there is no need to have to put in these independently by using a hydrosplit. R290 can achieve high efficiency levels having a+++ Vitality https://purethermal.co.uk/media-news/q4-launch-lithium-large-capacity-r290-ashp-from-pure-thermal-and-enerblue/