how do i bleed the header tank?

need to no if its a sealed system heating system or open vented . if its sealed the red expansion vessel is there to accomodate the pressure increase when the water heats up , is there enough water in the system ?,some boilers have a auto air valve ensure this is opened by turning or loosening the black cap on top .at the hot water cylinder you should have an air point at the coil thats where the flow and return from the heating system enters the cylinder open it and u should get air . to me sounds like u have a sealed heating system so ure prob going to have to fill it up using the filling loop normal pressure is 1.5 bar there should b a gauge on the red expansion vessel .

fitter
September 2005