The Grundfos CMB3-37 is the direct replacement for the CH2-50PC and CMB3-4
The Grundfos CM Basic is a compact pump designed for domestic and light industrial use. The booster unit consists of a robust multistage centrifugal pump and a generator friendly PM pressure manager. The pressure manager allows the pump to start and stop automatically according to demand and protects the pump from dry running. The CM Basic is the perfect solution if you are struggling with insufficient mains pressure, and can also be used with above or below ground water sources.
Pump Curve
Grundfos CMB3-37 Basic Pump Data Sheet / Curve / Dimensions
Grundfos CM Booster Brochure