Posted by pat on December 27, 2000 at 16:33:27:
I have a two pipe (formerly Moline Heat) steam system. Originally it was fired by a coal boiler, now a 175KBTU (Input) Wiel McClain boiler. The radiators have all been replaced from the older, larger style (large tubes) to newer styles with smaller tubes. The old steam vent that was at the end of the steam main is removed & plugged. The radiators all have either variable vents, or Gorton style vents that all close when hit with steam. All of the radiators heat very well & evenly, & the home is comfortable. I cannot, however, retain any vacuum in the system whatsoever. As soon as the steam begins to collapse following a heating cycle, the vents all (to varying degrees) allow air to seep back into the system.
I've toyed with the idea of installing a more modern type (electrical) vent where the old Moline vent used to be, and plugging all of the radiator vents, but am concerned that i may be wasting my money, time & risking damage to the system that works so well. I would, however, like to take advantage of the efficiency of vacuum boiling as the steam collapses.
Any thoughts?