Monoloop Hydronic heat & circulator piping

plaidskys

I am troubleshooting a one pipe, one zone hot water system with differential/venturie tees. It is providing little to no heat to the second floor radiators & first floor rads near end of the largest branch. They were bled and the circulator is running but it has an odd configuration The out feed for the circulator is 1 1/4 and leads to an existing copper branch of the same diameter. But the infeed is a 1" fitting in a reducer tee (1 1/4" in two 1" lines out - other feeds an indirect water heater). Can this single point of construction stiffle the entire branch?

EBEBRATT-Ed

Post some pictures if you can

plaidskys

I think I linked a picture nipple at bottom of the pump Is 1" nipple at top and rest of header is 1.25 will this create loe output across the larger branch?

plaidskys

Still trying for image