The pressure needs to between 1-1.5 bar on your gauge,you need to bring that pressure back up by opening the filling loop on the pipework under the boiler,what that doe's is fills the heating system back up with water which will bring the pressure back up on your gauge.When you have done that you then need to vent your radiators of any air then check the pressure on the gauge and bring back up if need be.
herbie, October 2008
