On Nov 26, 12:29 pm, wrote:
On Mon, 26 Nov 2007 11:23:56 -0600, "Steve Barker"

wrote:
the water leaves the heater at a certain temperature. It's not going to get
hotter, i don't care if you wrap 12 inches of cellulose on it.

There is heat loss from the pipes between the heater and the tap.
That's why the pipe feels hot if you touch it. Insulated pipes may
result in the water being closer to the original temp when it reaches
the point of use. In other words, the water at the tap will be HOTTER
than if the pipes are not insulated.

This is all off the top of my head, with no underlying data to
substantiate my theory...

I submit that in a residential environment, the amount of heat loss of
the water traveling through the pipes will be less than can be
accurately compensated for by the thermostat knob on the water heater.
We're not talking about precision instruments here, and even if you
could adjust the stat to compensate for the "reduced heat loss" the
amount of heat loss is so minimal that that the payback period for the
insulation would be extensive.