High efficiency and high output ground source heat pump with electronic expansion valve and electronic pump control. Designed for indoor installation. Two scroll compressors to flexibly and efficiently adapt to fluctuating heat demand with intelligent load switching between compressors to maximise compressor life. Supplied complete with integrated WPM Econ5Plus heat pump manager. Reduced operational noise through the use of an encapsulated compressor housing and a free-swinging compressor base plate.