Pumping away

Ryan1234

Since the common piping on a primary secondary loop (the space in between the tees) is considered a point of no pressure change, then shouldn’t the primary loop circulator pump away from the common piping? Would it be like having a circulator in between two expansion tanks if it were in front of the tees pumping into the common piping ? 

Ironman

The entire primary loop (the one where the expansion tank is connected) is seen by the secondary(s) as the PONPC, not just the common piping between the Tees.

Zman

It would really depend on where the expansion tank is.
I have never seen one piped between the tees.

EBEBRATT-Ed

@Ryan1234
I think your confusing two issues

The expansion tank is the PONPC no matter where it is installed, no matter what kind of system it is installed on, nothing to do wit primary/secondary


The closely spaced tee make the primary loop and the secondary loop "hydrolically isolated" from each other. A pump on the primary moving water has no effect on the secondary loop and vise versa

DanHolohan

The primary loop has the compression tank. That’s what defines it as the primary loop. Pump away for it. 

The secondary pumps see the common (shared) piping between the primary and secondary loops as their points of no pressure change. Pump away from those points.