Why Does My Steam Boiler Run Out of Water - All boilers need a constant supply of water from a make-up water source. In a steam boiler system there are vents that vent condensation. The vents can be found on the radiators and throughout the pipe system especially on large systems that serve larger buildings. Venting is limited to a small amount of the entire H2O and steam volume inside the piping and radiators but does need to be replaced.
Most of the steam condenses and is returned to the boiler through the return piping system either by gravity or a condensate pump. As the system uses steam it vents the condensation or steam and this displaces water from the steam system that needs to be replaced and the replacement H2O comes from a make-up water source. (more…)