On Fri, 06 Apr 2012 15:57:31 +0000, Martin C. wrote:

Q: Are the direction arrows (finally) correct?

Thanks for validating the direction of the water.
It turned out to be the opposite of what I had originally thought.

To summarize, this shows the direction of water at the ceiling pipes:
http://picturepush.com/public/7970324

That thermoswitch apparently senses temperature of stagnant water in only
one set of bathrooms upstairs (not the other).

This shows the direction of water through the pump itself:
http://picturepush.com/public/7970322

Therefore, this must be the flow direction in the pipes:
http://picturepush.com/public/7970410

With the result that stagnant water ends up back in the water tank:
http://picturepush.com/public/7970326

The whole system can be disabled in a variety of ways as there are at
least three water valves and an electrical thermoswitch and 120V power.

At the moment, it's disabled simply by unplugging the 120v power until I
figure out how best to mount the pump to the wall shelf with isolation.