Worcester 240 has been dropping pressure for about 4 weeks have kept on topping up, but getting worse, drained and refilled system and vented all rads, pressure still dropping and water on the outside wall where my boiler is, could it be prv?

kelly, April 2008

You probably need to charge the pressure vessle within the boiler. This absorbs the expansion of the water from cold to hot. Look inside the boiler and you'll see a tank (Usually red) there will be a valve on it the same as a car tyre valve. Release all the pressure from the system and check the pressure at this valve. It should be just under what you run the system at (1 Bar is the norm). If water comes out you need a new pressure vessle. If no water comes out just pump it up as you would a car tyre.
An alternative way to check if you have a pressure vessle problem is to watch the pressure while the boiler starts from cold. If you get a pressure rise of more than half a bar or so you have a problem. and need to carry out the checks above

Rupe, September 2008

THE EASIEST THING TO DO IS REPLACE THE RELIEF VALVE THATS WHAT I ALWAYS DO NOT VERY DEAR DO IT IN 15 MINS

PLUMS, April 2008