Mary Fisher wrote:

"Steve S (another one)" wrote in message
...

"Mary Fisher" wrote :
"Steve S (another one)" wrote :

If it's the return temp that's important, then I have a supplementary
question... I understand that hot water in a cylinder should be heated
to 60C in order to prevent the growth of Legionella bacteria. Is this
correct, and if so, how do I reconcile the two requirements -- return at
55C or less, but hot water = 60C?

The 60C is only for the first use, to 'kill' any harmful bacilli in the
equipment.


Hmm. Could the tank in the loft not be a potential further source of
contamination? It's not accessible to anything larger than an insect,
but... I'm just trying to anticipate my wife's arguments here, and she's
somewhat paranoid about germs.

Does she breathe?

That's the least of her worries, but it's nice to see the technical
ignorami (Dynamo Hansen and the She-Devil) focusing on the wrong thing.