Mysterious Radiator Problem

PackRat

I live in an old 7-story apartment building; I live on the 5th floor.  We have a low-pressure, single pipe steam heating system.  I have original heavy cast iron radiators.  For the whole time I lived in the building (many years) all three of my radiators worked just fine.  Then at the end of last year's heating season, my living room radiator stopped heating up beyond the first or second ribs (there are 10 total).  The problem has continued this year.  I have tried both Hoffmann and Gorton vents; the radiator has been raised several times; but the problems persist.  When the boiler is firing, the first rib will get very, very hot to the touch.  The next rib is generally somewhat hot, the third may get warm; the rest are stone cold.  Oddly, once or twice this year, 4-6 of the ribs have heated up all the way, but then the radiator returns to the pattern of 1-2 ribs heating up.  And today, the coldest day we have had in a very long time, only one rib heated up.  Our heating engineer was here today and could not figure out the problem.  There is currently a Gorton vent on the radiator and it is hissing very slightly.  Also, the radiators at the top and bottom of my tier (7 floors) heat up perfectly, as do most of the others in the tier.  The radiator on the 2d floor also has some problems, but I don't know the nature.  Any suggestions of what to try next would be very welcome.

nicholas bonham-carter

Sudden change for the worse

Something must have changed in the whole system, which has caused your rad to underperform. The job of the heating engineer would be to track it down.

Try to find out what changes may have taken place (such as a new badly-installed boiler), and post the list here for advice. --NBC