I've just discovered that my Baxi 133HE Plus is losing water pressure on the central heating side causing a droning noise from the boiler when hot water is drawn off. When the water is topped up via the filling loop the noise stops, however I have had to top up the system several times in the last couple of weeks, there are no leaks in the radiator system and there is no air in any of the radiators so I'm baffled. Both the radiators and the hot water system are heating as required. Has anyone experienced a similar problem ?
Cheers
Dave
Cheers
Dave