I have gas central heating.I noticed this week that hot water is entering the small header tank in the loft that feeds the radiators from the vent pipe.The heating seems to be working ok.Could this be a boiler thermostat problem?Any suggestions please.

Dave D, December 2009

Sounds like it's pumping over. Can do this if a new pump has been fitted. Try turning the pump down and see if this stops it.

M, December 2009