SJC wrote:
"Tony Wesley" wrote in message oups.com...
wrote:
What exactly is the risk you refer to in a system designed to be
riskless?

The risk that the system will not work exactly as designed.

These guys show a draindown system as one of their options.
I don't think that they would recommend something unproven.
http://www.thermomax.com/Drain%20Down%20DHW.htm

Why does he think there is a risk of incompetent engineering in one
system but not another?

NT