Bob F wrote:
Martin C. wrote:
On Thu, 05 Apr 2012 16:43:35 -0700, Bob F wrote:

You could disconnect the wire from the pump to that thermostat above
it.

If it's as simple as disconnecting the power, and if nothing 'bad'
happens when I do so, then that's a simple plan of action.

Or, you could try remounting the pump motor

I'm realizing from this discussion that you're right. It's the
'mounting' that is probably shaking the walls which is probably
what's 'amplifying' the noise of the motor hum as it sound's louder
in the living quarters above than right in front of it.

Did I draw the direction of current correctly in these pictures?

Where pipes connects to the tank:
http://picturepush.com/public/7966064
How pipes connect to the pump:
http://picturepush.com/public/7966063

The pump should either pump hot water out of the top of the tank,
through the loop, and back to the bottom of the tank, or it "sucks"
water through the loop from the top of the tank, back through the
return line and pumps it back into the bottom of the tank. There
should be an arrow on the pump body indicating the direction of flow.

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.