cider - it does have a modureg which got me thinking. I stuck a meter across it to check the volts, it doesn't seem to change from around 21volts even if i reduce the water flow, suggesting there's not a lot of regulating going on.
I then swapped the DHW and CH thermistors over, thinking that...
Hi I've got a Worcester Bosch 280RSF with an overheat problem - boiler boils and reset button pops out after drawing HW.
Having read other posts on this forum previously I recently replaced the W-W exchanger thinking this was the most likely cause. The existing exchanger was reasonably clean...