Radiator Sysytem-Radiant System Tie-in pumping issue.

ahplumbing

Good morning, I'm an "old timer" with no experience with radiant heating! I only know a little theory on radiant. That said, yesterday I was called to troubleshoot and issue where radiant was installed in an addition over the summer that is providing erratic heat, chilly majority of the time and too hot other times. The original installer told the customer that that is how radiant heat works, nothing he can do. Customer led me to believe the person was what I call a "piper," by looking at other plumbing work he did there. Any way the house system has cast iron radiators and two-pipe supply and return steel piping with the old style circulator pumping back to the boiler. For the new radiant the installer tied into a supply and return opening on the trunk and installed a circulator on the supply branch piping away. There is only a circulator, no type of temperature mixing valve or flow controls. Further, this circulator is controlled with the system, meaning when the main system is satisfied and shuts down, so does the one for the radiant. The system runs on 180-degrees. My limited knowledge tells me that this should have been tied into the boiler on a zone independent of the radiators, with the circulator pumping in the same direction of the main circulator with a mixing valve and flow controls. Possibly below the main system circulator. I've attached photos of both circulators. Any thoughts? As I said, my knowledge of radiant is limited, and I don't want to take "pot shots" at correcting someone else's issue. Thanks!