Hi Gents, Your assistance please- I have a Eurostar 90 which has an intermittent lock out issue. What happens is as follows- the boiler will fire up in the morning and heat the hot water and also the central heating, it will run for maybe a few hours and then cut out, a reset will get it working again, sometimes the boiler will run for 8 hours plus without any issues, however i've noticed that sometimes it will stop igniting the fuel but still run and then reignite its self. Other times it will not reignite and lock out. I service the boiler every year, new nozzle, clean the baffles which are spotless and never sooted up. A heating engineer friend will set up the gases for me. Hes away on holiday at the moment-- To rule out fuel flow/contamination I've checked for water in the trap next to the tank, thats all good, checked the filter at the boiler again thats fine. Removed the photocell which is spotless. The motor does seem hot to the touch. Not sure if this has anything to do with the fault but there are a few knocks to be heard in the pipework when the boiler is running. Thanks for your help here, its very much appreciated.