Water leaks out of the 10 bar domestic safety valve on my boiler when it has been on for a while, its running like a tap out of the pipe that is outside the house and the boiler is running continually trying to heat up the water thats escaping.Central heating side is still working ok and there isn't any significant increase in domestic water pressure so I'm not sure why this is happening, anyone got any ideas.

jonathan shepherd, October 2007

1/ Check the pressure; it may just be doing it's job and saving you from a burst boiler !
2/ Check temperature; same reason as 1/ ( They are typically dual action, ' Pressure and Temperature.)
3/ Change it; they do age; then weep a little which quickly wears a groove in the seat leading to large and expensive flow.

GMR, November 2007