système à vapeur à deux tuyaux

OBS: (...) les installations de chauffage à vapeur (...) Le système de chauffage à deux tuyaux (...) comporte deux tuyaux, dont un d'amenée pour la vapeur, et l'autre de retour, plus petit, pour l'eau de condensation.

CONT: Two-pipe steam heating systems ... are designed to operate at pressures ranging from subatmospheric (vacuum) to high pressure. Although they use many practical piping arrangements to provide up-flow or down-flow systems, they are conveniently classified by the method of condensate return to the boiler. Condensate can be returned to the boiler by gravity or by use of any one of several mechanical return means.