Rafal Kaczynski
Dear Steve The MPE 322/328 is designed to control water circulation in primary hot water and central heating circuits, by diverting flow to either circuit or to both simultaneously using a single valve. For convenience the two neon indicator lights illuminate indicating which port is open. When the manual lever is moved to the right, ports A and B are open, this is used when filling, venting or draining the system. The spring return, Mid-Position actuator – valve rests in the hot water only position. So if black water is dripping from acurator it means that aludge is build up in your CH system and required flushing. I hope this will help Regards Rafal
