HELP, I have a Worcester 240 boiler. When ever I wanted to put the heating on I have to increase the pressure in the system as it would drop to 0 whenever the heating was turn off. I was told by someone that the PRV had gone so I have replaced it today only to find that when the heating is switched on within 2-3 minutes it has gone up to 3 bar so I have to quickley turn it off so it doesn\\\'t blow the pressure out the over flow. When the heating is off it does return to 1.5 bar (which I think is correct). How can I stop it rising to that much pressure, surely it can\\\'t be right.