My neighbor is in the process of hooking up a used Keystoker Coal Fired Hot Water Boiler. He got the thing working after doing a bunch of research on this site. My question is this, when filling the supply and return lines with water should water come out of the domestic coil? While we were filling the lines water started coming out of the domestic coil supply and return. He currently does not have the domestic coil plumbed we just installed valves and turned them off. Is that normal or is his coil shot?