一、前言 取暖热水管网,习惯上几乎都是采用双管制闭路循环系统。由于这种系统运行稳定可靠,控制调节比较简单,而且在实际运行中已积累了丰富经验。因此,该系统已成为热水管网的基础。迄今绝大多数有关热水管网的设计,运行以及维护管理等规程,无一不是以此系统为依据而编制的。各类关于热水管网的书籍和刊物,也多数是论述这种供热系统。然而,对于某些具有特殊情况的地区 I. INTRODUCTION The heating hot water pipe network is almost always a double-controlled closed-loop system. Due to the stable and reliable operation of such a system, the control and adjustment is relatively simple, and it has accumulated rich experience in actual operation. Therefore, the system has become the basis of hot water pipe networks. The vast majority of procedures concerning the design, operation, maintenance, and management of hot water pipe networks have been compiled on the basis of this system. All kinds of books and publications on hot water pipe networks also mostly discuss such heating systems. However, for some areas with special circumstances