One pipe Steam system

nicholas bonham-carter

there could be a horizontal element in that line leading to the 2 rads which has sagged, and is blocking the air and steam. can you check it with a level; or hear it panting?
you already gave it the supreme vent test- the open pipe.
next time you make such a check, why not just take the bonnet off the valve.
remember also that the main vents do 3/4 of the air removal, so don't rely solely on rad vents.
another factor could be high pressure causing the water in the returns to stack too high.--nbc

Rob_38

Air in a 1-pipe steam system

My customer has 2-1st floor radiators at the end of the 2 main supply lines that have cold pipes. Every inch of pipe before and after these 2 risers is hot. Even the 5 second floor radiators heat good. So I took the radiator valve completely loose and waited for steam and it took for ever to get there. The pipe stayed cold for a long time.
I am thinking that I need to put a vent on both supply lines before these 2 risers.
someone give me a good idea!!

Unknown

I'm a bit confused. When you say you took the radiator valve completely loose, do you mean you completely disconnected the radiator from the pipe or loosened the radiator vent (valve)? If it was the vent, I think I'd then check the valve going into the radiator which maybe non operation and in the closed position. I've had a few that turned fine but stayed closed.
Just a thought.