I have a Waterfurnace Synergy on an open loop. It was installed in 2002 and has been working great. This winter the unit quit working and now I get a water flow error as soon as the unit starts up. In order to check water flow through the system, I manually opened the TACO 5101 valve and no water moves at all. I am guessing that my outflow pipe is blocked (or frozen). Here is my question - does the Waterfurnace have to be powered up for water to flow through it? Or - if I open the valve should water flow through it whether it is powered up or not. Thanks in advance for your help!