Thanks for the fast answer. I have tried the red expansion valve, I pushed the needle and it let air out. The boiler seems to run ok if i do not put the central heating on. It stays at a constant pressure 1.5 bar uaually. As soon as the central heating comes on (when i turn the room stat from 0 to 18 degrees) the radiators will go to the correct temperature for about 1 to 2 hours and then the PSV kicks in as it has gone over 3 bar. Any suggestions anyone. Thanks for the reply ryan.
monkey hanger
May 2008