Has happened before this boiler seems to trip out when its reached peak temperature. The thermistor was changed previously(about 2 years ago) and had no further problems until recently. A wireless stat has been fitted ant a new thermistor fitted once again(as the fault re-occured). Your now lucky not to have to reset the boiler once a day,which is a pain as its in the loft!!. Any ideas would be grateful. It seems when the boiler is on constantly for the CH, it reaches its optimum temp and then cuts out,having then to be reset to allow the boiler to continue. 
