一、前言 传统的取暖热水管网都是采用双管制闭路循环系统。由于这种系统具有运行稳定可靠,控制调节比较简单等优点,因此获得广泛采用,并在实践中已积累了丰富经验。迄今几乎所有的热水管网设计、运行以及维护管理等有关规范,都是以这种系统为基础而 I. INTRODUCTION The traditional heating hot water pipe network adopts a double-controlled closed-loop system. Because this system has the advantages of stable and reliable operation and simple control and adjustment, it has been widely adopted and has accumulated rich experience in practice. Almost all the relevant specifications for the design, operation, maintenance and management of hot water pipe networks have been based on such systems.