Possible pipe blockage for radiator???

Timco

Your pump may be getting weak. If you have a 2-pipe system, close some rads on the main floor and see if that sends flow through the cold rad. If no, maybe it has an air-lock and that loop needs a good purge...There is typically not the kind of stuff in a HW system that would cause a blockage. Maybe a dirty strainer somewhere? Can you post near boiler & basement pipe pics?

Tim

gbp

Pipe restriction for radiator

I have a 2 pipe hot water boiler. Radiators on 1st floor are OK and all but one on the 2nd floor are OK. The one in question has a feed & return off of the mains, all of which are black iron which then go to copper as it comes into and out of the finned radiator. There is also a union in each pipe near the mains. This radiator stays cold---2 radiators that are inline behind it are OK and the one in front of it is OK. I pulled the radiator, blew it out with water, no restriction. Valve is OK also. Slowly started to fill the system with water and noticed water rising in both the feed & return----which tells me there isn't a full restriction in either line. When I went to drain the system again, I noticed that the return line started pushing water out of the top the line (where the radiator connects in).
Is this an indication of a partial restriction???
Is it common for restrictions to occur at the unions or elbows where they tie into the black iron pipe?

Timco

Is there a flow restricting disc in the union of the cold rad? If no, you may need one on the rads that heat best & fastest on the main floor. Try closing a few valves on the main floor and see if you get flow. I doubt you have any blockage. Is your system gravity? Pumped? Zoned? A wise man once said "be the water"...where would you go to make the easiest trip from supply to return? As for the filling thing, water always seeks it's own level....

Tim

gbp

I don't know of any flow restriction discs. System has a circulator pump. It was zoned heat at one time----separate main for 1st & 2nd floors, but the valve for the 2nd floor is stuck in the OPEN position.
This radiator worked at one time and nothing has changed in the system (boiler, pipes, radiators, etc).