Posted by Harold Kestenholz - Hydronic Network on September 25, 2000 at 09:18:45:
In Reply to: Info on late 1920s American Radiator Company "Arcoflash" system posted by David on September 24, 2000 at 16:49:44:
The historian in steam heat is Dan Holohan at HeatingHelp.com.
Some ways to find if the system is water or steam are: Look at the pressure rating of the pressure relief valve on the boiler. A steam pressure relief will be 15 psig, a water pressure relief will be 30 psig. A steam boiler without a glass water level gauge will have three brass 'try cocks' on the vertical side of the boiler to see how much water is in the boiler. If there are no vents on the radiators, the system is most likely a steam system with the steam return on the bottom so the air is vented out the bottom as steam below 15 psig is lighter than air. The air would be vented out of the supply and return main vents.
Since this is the 1920's, the fuel was wood or coal, so the heat-up time took many hours and vents could be small for gradual venting. The heat cycle was 8 hours instead of the modern hourly cycles.
If this was a vacuum vapor system to extend the heating cycle overnight, vents ar every radiator in the system would be more difficult to insure a good seal as the pressure dropped below atmospheric, so one main vent would be easier to control. there may be a squarish box near and above the boiler acting as an air trap.
Post a Followup