一、问题的提出目前,多层和高层民用建筑物中的热水采暖系统,经常被设计成为带有闭合管段的垂直单管系统形式(或称垂直单管跨越式系统)。对于此种采暖系统形式较之垂直单管顺流式系统是否优越,已引起不少设计者的争论。争论的焦点是:带闭合管段的垂直单管热水采暖系统是否会提高进入下层散热器的水温,从而改善上、下层之间存在的垂直热力失调状况。结论应该如何?至今尚缺少理论上的探讨。为使设计者合理地选择系统形式,本文提出这个问题,并予以讨论。二、设闭合管是否会提高进入下层散热器的水温 1. Problems raised At present, hot water heating systems in multi-storey and high-rise civil buildings are often designed as vertical single-pipe systems (or vertical single-tube spanning systems) with closed pipe sections. The superiority of this type of heating system over vertical single-pipe downstream systems has caused many designers to argue. The focus of the debate is whether the vertical single-tube hot water heating system with a closed pipe section will increase the water temperature entering the lower radiator, thus improving the vertical thermal imbalance existing between the upper and lower levels. What should be the conclusion? There is still no theoretical discussion. In order to make the designer choose the system form reasonably, this paper proposes this question and discusses it. Second, if the closed tube will improve the water temperature into the lower radiator