... Efficiency&Muti-fuction LTWH Series High Quality Ground Source Heat Pump for Houses and Commerical UseHeat Pump System:Brifly Introduction: ... one way valve.HYDRAULIC CIRCUITBuilt with user side and source side water inlet/outlet connectors, water discharge connectors, ... 63.23.54.04.54.86.1Control SystemDedicated heat pump controller,PID regulatorSecurityOverload, high voltage, wrong Phase, water, oil, ...