Posted by Harold Kestenholz - Hydronic Network on March 15, 2001 at 13:47:12:
In Reply to: Webster Modulation System posted by Dave Young on March 15, 2001 at 10:10:48:
1. Broyles, C. C., paper, "The Webster System of Steam Circulation." c. 1911-1925. (Memo from East Tennessee State Normal School (ETSN) President Sidney G. Gilbreath found in the paper).
http://cass.etsu.edu/archives/UFindaid/u177.htm
There were several trap designs used during the early years of the last century. The primary purpose was to prevent water leaving a boiler, as in a Hartford Loop, and separate air from steam in the system. The Webster unit performs those tasks. That device is a drop loop from the return main with a vent on top - all in one.
The operation of the sytsem is not different from other two-pipe steam systems. That is - water turns to steam, steam hits radiation, condensate falls back down toward the boiler through traps that isolate the steam from the condensate return. The air vent allows air to be forced out of the return to allow steam to reach the parts of the system that otherwise would be blocked by air.
The check valves prevent water from forcing backward from the boiler into the return, keeping the water level stable. The major yearly or more frequent repairs to be done other than to test and adjust the boiler controls are to flush the return piping and boiler of rusty sediment and to clean the check valves so they can seat properly. The Webster part will perform as designed.
If the boiler can bring steam up to pressure and fill the system within 40 minutes, the burner input is enough to provide heat in the winter.