flooded radiators

ross moore

My mom lives in a group of row houses (17 total) that use a central boiler. They have 1-pipe low pressure steam. Recently, one of her radiators on the first floor started leaking out of the air vent (water dribbling out the vent hole; not sputtering). The radiator was valved off and cool to the touch. I unscrewed the vent and water drained out, so the radiator was completely flooded. It appears the radiator valve has a slow leak, allowing steam in but not allowing condensate back out, resulting in flooded radiator. We discovered that many of the other homes were having a similar problem (either radiators just being hot even when valved off, or being flooded like my mother's). They are having a plumber come out to fix/replace the valves, but I was wondering what would cause all of these valves to fail at roughly the same time?



Another thing you should know is the boiler was replaced last fall, so the homeowners are understandably suspicious of the new installation. The new boiler and installation was much better than what was there (sizing and near boiler piping had been all wrong). The installer has been back to check on it at various times and at some point he had raised the set pressure to 10 psi (cut-in stayed at about 1/2 psi). I thought maybe the higher pressure was forcing steam through the valves when it couldn't before, so I set the pressure down to between 4 and 5 psi. This didn't really fix anything, and really those valves should be able to hold against way more than 10 psi. Like I said, the homeowners are getting the valves fixed, but still want to know why the valves have been a non-issue for years and then have become an issue at the same time? I should also note that they are calling the installer to see if he has any thoughts.



Any ideas are welcomed.

Alan (California Radiant) Forbes

Flooded

One-pipe steam is meant to work at very low pressures; that is why the pipes are so large. Many of your Mother's problem will go away once the pressure is set properly.



Pressuretrol should operate between .5 and 1.5.



Vaporstat should operate between 4 oz.and 10 oz.

Unknown

Lower the Pressure!

Follow Alan's advice. Residential steam systems are designed to operate at a 2 PSI maximum and the lower the pressure the better the system works. The Empire State Building in New York works at under 3 PSI !

- Rod