Vokera boiler pressure loss problem?

Check the external wall where the boiler is fitted. There will be a 15mm copper pipe (Blow Off). If you can, try and feel if this is dry. Pressure can be lost this way. If it is dripping it will either be an expansion vessel/hose to vessel problem (Turn heating on and see if pressure increases sharply) or a faulty Pressure relief valve

Paul
March 2010