"RayV" wrote in message

Again, no zone valves just the flo-control 'gravity flow' preventers.

Again, check to see that they are operating properly. Mine have an
adjustment thumb screw on the top of them.


I'm guessing the _main_ circulator pump is left-over from before the
system was zoned.

Sure sounds that way. The main pump would have enough force to get water
past the flo-controls.