... EVI air to water heat pump:1. indoor unit included 4 way valve, liquid storage tank, pcb, heat exchanger, auxiliary heater, pressure ... boiler, we recommend you use a buffer tank also.4. EVI comrpessor Clever design and stronger adapt Clever split ... apartments, villas, offices, configuration forms don end equipment (fan coil, floor heating, thermal insulation, etc.), combine with indoor water ...