Booster unit for constant pressure for residential building service and commercial building service. They can also be used in watering systems. NKVE are 1, 2, 3 or 4 multi-impeller vertical centrifugal pumps with coupling with variable frequency drive MCE-P installed as standard. The models with NKVE 10 S, 15 S, 20 S have the parts in contact with the liquid in AISI 304 stainless steel. The models with NKVE 32, 45 have the pump body and upper flange in cataphorized cast iron. The impellers, diffusers and pump casing are in AISI 304 stainless steel. The MCE-P variable frequency drive is installed on each pump, it allows constant pressure. One control unit and one pressure sensor per unit. One delivery check valve and one expansion vessel for each pump. Suction and delivery manifolds in stainless steel AISI 304. On request X version with materials in contact with water in stainless steel AISI 316. The units are supplied assembled, set up and tested directly in the factory and complete with installation instructions, maintenance instructions and text report. IE3 electric motors. DConnect ready (DConnect Box supplied separately).