Why is the heating system with upper supply air and lower return air vertically unbalanced?

In the heating system of multi-storey buildings, hot pressing and air infiltration load are not considered enough in the design; Or because the temperature of heating medium is lower than the design value and other comprehensive reasons, vertical imbalance often occurs. That is, the phenomenon of heating up and cooling down. With the increase of building floors, the lower the temperature of heat medium, the more serious the vertical imbalance. There are many ways to solve the vertical imbalance. Different methods have different effects. Mechanical circulation double-pipe hot water heating system: the main water supply pipe of the double-pipe upper supply and lower return system is located at the top of the system, and the main return pipe is located at the lower part of the system, generally in the trench. Water supply pipes and water pipes of radiators are set separately, and each group of radiators can form a circulating loop. The water supply temperature of each group of radiators is basically the same, and each group of radiators can adjust the flow rate of heat medium by itself so as not to be affected.

(2) Mechanical circulation single-pipe hot water heating system: a single-pipe upper supply and lower return system, in which the water supply and return risers of radiators share a pipeline, and the radiators on the risers are connected in series to form a circulation loop. From top to bottom, the water inlet temperature of each layer of radiators is different, and the temperature decreases in turn, so the heat medium flow rate of each group of radiators cannot be adjusted separately. In order to overcome the shortcomings that the single pipe can not independently adjust the heat medium flow rate and the inlet temperature of the lower radiator is low, a single pipe leapfrog system is produced. Hot water is divided into two parts before the radiator, one part flows into the radiator and the other part flows into the crossing pipe.

(3) The system of heat release theory in the next cycle under mechanical cycle: This system is generally suitable for occasions where the top main pipeline is difficult to lay and buildings with basements. When there is no basement, the water supply return pipe is generally laid in the bottom ditch.

(4) Mechanical circulating hot water heating system: During mechanical circulation, the horizontal water supply main pipe of the heated water heating system is laid in the middle of the system, and the upper system can adopt the upper supply and lower return type, and the lower system can adopt the upper supply and lower return type. The middle supply system reduces the vertical dislocation caused by too many upper supply floors and lower return floors, and at the same time, it avoids that the main water supply pipe blocks the top floor window and the top floor beam is too low to open. The central supply system can be used to increase the floors of the original building.

(5) Heating system with mechanical circulation and hot water supply: the main water supply pipe of this system is set above all radiators, the main return pipe is set below all radiators, and the expansion box is connected with the main return pipe. Backwater flows back to the boiler through the expansion tank and is sent to the boiler by the circulating water pump.

(6) Heating system with mechanical circulating medium-recycled hot water: In the heating system with medium-recycled hot water, the main backwater pipe can be located under the roof or in the mezzanine of stairs, and the pipe trench can be omitted. During installation, the lower end of the riser should have drainage and sundries in the pipeline. An automatic drain valve or other drainage device shall be set at the end of the reflux header. The system is suitable for multi-storey buildings where ditches are not suitable.

(7) Horizontal series heating system: a riser is horizontally connected in series with multiple groups of radiators, which is called horizontal series heating system. According to the connection mode of water supply pipe and radiator, it can be divided into two types: downstream and leap, which are in mechanical circulation and self-circulation state.