doesn't really matter what heat settings you have set the boiler should be able to cope with minimum to maximum. theres obviously something getting too hot and the o/h stat is protecting the heat exchanger. could be showing its age or system condition. scaled/sludged exchangers struggle to transfer their heat for example.
turn stat down a bit on boiler, its no spring chicken
iain
September 2008
howtomendit.com for free repair help, information and advice.
