Wilo-Sinum is the ideal solution for pressure maintenance, de-aeration and topping up in closed heating installations where standard diaphragm expansion equipment is limited. The pressure expansion automat for pumps includes an integrated pressure-maintenance, degassing and topping-up function in closed heating and cooling systems. The large series of closed vessel sizes allows adaptation to a large number of applications for guaranteeing constant system pressure. The system offers continuous degassing using three selectable operation modes and thanks to the digital and analogue inputs, it can be optimally integrated into an existing building management system.