A one-pipe steam system is a type of heating system commonly found in older homes and buildings. In a one-pipe steam system, steam is generated in a boiler and then sent through a single pipe to heat the radiators in the building.

The steam travels through the pipe, which is sloped slightly downward towards the radiators to allow for proper drainage of condensation. As the steam enters the radiator, it condenses back into water, releasing heat in the process. This heat warms up the room and provides heat for the building.

Single pipe steam is one of the least efficient heating systems – the steam and condensate passing in the same line causes more steam to condense in the lines resulting in a loss of useful steam.  It is also significantly noisier then all other steam/water heating systems due to “water hammer”, as the hot steam passes and boils the cooler condensate in the lines.

Single pipe steam is an open system. Each rad and end of line has an air vent to allow the air to leave as the steam arrives.The air vent also admits air back into the system when steam is not present.