Throttleing the valve

Reinvent

I live on the second and third floor of a two family house with gas fired one pipe steam heat going to old radiators. When I first moved in, the third floor would never heat up sufficiently (thermostat is on the 2nd flr). I replaced some vents (which helped a little). The following year I realized the valves on the 2nd flr rads were wide open so I turned them down abought half way. Presto! We now had heat on the third floor. But now I have read here that you are not suposed to do that. Why not?

Fred Harwood

Valves

One-pipe steam valves should be either fully open or fully closed because the condensate returns to the boiler back though the valve even as steam enters. Restricting the valve too ofter speeds up the steam and prevents the condesate from leaving the radiator, which then floods and spits water out the vent. (Even a half of one PSI will stack condensate 14 inches.) Also, because tthe condensate can't get back to the boiler, often it will look like a low water condition. Best to leave the valve fully open and resolve what looks like a venting problem with the other radiators.