Am having a problem with my boiler. Its in a duplex house and it feeds cast iron radiators in the second floor only. The boiler fires up OK put the radiators dont get hot, just warm. In the basement the supply pipe is hot but the return lines are just warm. Ive checked the aquastat relay box and the temp in there is set to 180 (low) 200 (hot). Also the pump and reducing valve was changed two weeks ago. Can the problem be the circulation pump? How do I know if its working correctly? When the pump was installed I could feel the water reciculating in the pipes but not anymore. Is the boiler just heating up standing (convection) water and thats why the radiators dont get hot?. The pump is a series Taco 005 pump.