双管热水供暖系统重力循环压力的探讨

针对《实用供热空调设计手册》中提出的“下供下回式双管热水供暖系统仅适用于四层以下建筑”的规定，分析双管下供下回式系统垂直热力失调比上供下回式系统减少的原理，并通过改进系统设计较好解决下供下回式热水供暖系统的排放空气的问题，并用实际工程案例证明，双管下供下回式系统可用于６层，甚至８层建筑的热水供暖系统。

On Nature Cycle Pressure of Machine Cycle with Double Tube Hot Water Heating System

It is brought forward in Heating Air Condition Design Handbook that machine cycle with double tube underside feed and underside return flow hot water heating system is only applied to the buildings which are no higher than four stories.The theory is analysed in this paper,that upright thermal power maladjustments in double tube underside feed and underside return flow heating system is less than those in double tube upside feed and underside return flow heating system.The problem how to discharge air in the double tube underside feed and underside return flow heating system is solved by improvement of system design.Accordingly,double tube underside feed and underside return flow heating system can be used to the buildings which are as high as six even eight stories.This has been proved in practical engineering cases.