Desperate- Kindly Help

NY7374

Cape Cod style home cira 1950's.Boiler (PB) and burner (oil) installed late winter 2011.  1 pipe system. (one pipe feeds water, one pipe returns water to boiler). End of 2011 heating season  heard banging from pipes, shortly thereafter, heating season over, No seperate hot water heat= system runs for hot water= no banging of pipes. Turned heat (thermostat) on for first time this season. Rusty water is visable in water glass, which water level is topped. Turn down thermostat-Remove water to bring level back to 1/2 in water glass. Approx 8 minutes later, pipes begin to bang getting  increasingly louder.Attempting to trace specific pipe where banging noise is coming from, I discover water rushing down basement wall.. Turn off thermostat and go to radiator above where water is coming down wall. Radiator is spewing water from bleeder valve ( replaced when boiler/burner installed) and water appears to be slowing attempting to seep from the "cap" of the pipe that comes up from floor, into radiator. Noting water glass fills to top again. Pipes leading from boiler to radiators are all hot. Area where it appears the return pipe ( return to boiler) starts ( ceiling of basement- directly  below radiator that spewed the water)  the very top of pipe is hot, however continue to follow this pipe and it is cold. Although opinions are that there is a clog in return pipe which is not permitting water back to boiler= water/condensation is backing up through feed pipe and returning to boiler, no one seems to agree on how to resolve this issue. Some say chemicals, others say replace section of pipe where clog appears. No one has addressed if it is possible radiator needs to be pitched. Its is getting COLD... and I am fearful of turning heat on until the issue is resolved. Any thoughts - opinions- would be greatly appreciated!  Thank You!!!!

Enreynolds

consolidated to single thread

consolidated

Eric