On Fri, 06 Apr 2012 08:04:45 -0700, Bob F wrote:

Trader4 was right that the water returning from the loop should go into
the cold water return at the top of the tank, although it could tap into
a "T" at the drain valve at the bottom of the tank.

Here is a picture of where the hot water taps INTO the tank:
http://picturepush.com/public/7970412

Here is a picture of the hot water flow FROM the two upstairs bathrooms:
http://picturepush.com/public/7970410


Notice the tank is actually the second in a series of two tanks hooked up
in parallel. It appears cold water arrives from outside into the right-
most tank, which heats it up and then sends ALL the water to the left-
most tank which again heats it up (I guess).

Q: Do I have enough information now to describe how the system works yet?