noun
: the whole system (as of boiler, pipes, and radiators or of furnace, ducts, and registers) used for heating an enclosed space (as a building or group of buildings)
noun
: the whole system (as of boiler, pipes, and radiators or of furnace, ducts, and registers) used for heating an enclosed space (as a building or group of buildings)
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012