Vaillant Boiler Problems

[jibby1]

Hi,

I've noticed over the summer that water is occasionally dripping from the overflow pipe of my Vaillant Ecomax boiler.

I've just switched the heating on (I've only been using it for hot water during the summer) and I noticed that the pressure valve is above the max area and is at 3 bars.

Additionally, two of the radiators downstairs (the last two on the system) are only lukewarm at the top and cold everywhere else.

I turned the handle underneath the boiler and reduced the pressure down to 1.5 bars but it rose back up to 3 bars within a couple of minutes.

Can anybody help before I call a plumber out?

Thanks