Posted By Nigel Hammond Can any one tell me if you have to set the temperature of a combi boiler to >60 degrees C - to prevent growth of legionella bacteria. I know you have to do this for normal hot water calorifiers - but wondered if this is not necessary in a small domestic setting with a combi-boiler because only a very small quantity of water is stored.

Posted By John Webster If this is a normal domestic combi installation, in a relatively modern copper piped system, then there is no need to worry about legionella. The hot water in use comes direct from the chlorinated rising main and is heated without venting, so retains its chlorine. There is no storage and no circulation. My only precaution - if any - would be to clean and bleach the shower heads once a year. As for the boiler circuit, this is effectively sealed and in any case will be operating at a temperature well in excess of 60 deg C