One pipe steam system - some radiators no longer working

Alden Maddry

I have a one pipe steam radiator system in a 3 story 1931 brick house... this year a number of radiators that used to heat up no longer do so - they are stone cold. (but luckily some of the other radiators are still cranking out heat). I took off one of the air vents from a non functioning radiator and it didn't seem to be clogged - I could blow air through it. what is my problem?

leaking

Try new vents. Is there more than one return vent on the boiler, it could be bad. 

Alden Maddry

Could a non working vent in one radiator prevent steam from getting to a different radiator?

Jamie Hall

Not in a one pipe system.

mattmia2

Cold be a plugged main vent on that part of the system. Could be water no longer able to drain somewhere because something has sagged or become become plugged. Could be the boiler is now throwing water in the mains because something changed about the water quality in the boiler. Any work at all done on or near the system?

Long Beach Ed

If the boiler is producing less steam, perhaps through a combustion problem, or if venting was messed up, distribution would favor some radiators over others. If the thermostat was satisfied on this unbalanced system, it would turn off before some radiators heated.

leaking

It could be many things. You mention sagging, do all radiators have a slight pitch back to the valve? Do you see sagging ? Vents do go bad and not seal but you should get some heat . No heat would have me start at the boiler and the main vents, and things others mentioned. Replacing all radiator vents and main boiler vents if they are old is a good idea. What pressure does the system reach, is it lower this year? 

Alden Maddry

I removed the last vent in the return line... to see whether it was working - I could blow air through it... then put it back and then everything seemed to start working - except for the one radiator that wasn't working.

mattmia2

Look at the vent and the valve and the pitch of the runout on the radiator that isn't heating. Does it heat if you take the vent off?

leaking

Just blowing air through a vent means nothing. It has to close and seal. I just got a new vent that’s bad! What a pain in the a. 

Jamie Hall

leaking said:

Just blowing air through a vent means nothing. It has to close and seal. I just got a new vent that’s bad! What a pain in the a. 

Oh dear me no. A complete misunderstanding of how venting works. If the vent is not open, the air can't get out and the steam can't get in. Result, no heat.