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Hi, I'm s gas engineer, 505609 and I'm struggling with a fault on a csi 85, the customers description is that the boiler keeps going to lockout either during but mainly after s shower,he thinks it does it in ch mode but can't say for definate as its random and hasn't been using ch much, every time I've been it's on the lock out (solid red light) so I reset but it's never done it while I've been there, I've spoke to raven heat tech and they told me to change both thermistors so I did, same problem, spoke to them again and the told me to clean the plate to plate heat exchanger out with kettle descaler which I did but same problem, also changed over heat stat but no joy, any help would be appreciated , thanks.
