Why should the indoor hot water supply system be equipped with circulating pipes?

Indoor hot water supply system can be divided into the following types: pipeline structure of full circulation, semi-circulation and non-circulation hot water pipe network:

Full circulation pipe network refers to a hot water pipe network in which all water distribution main pipes, risers and branch pipes are equipped with corresponding return pipe to ensure the water temperature at any point in the water distribution network. So that the hot water temperature of each water distribution point in the system has little difference.

Only the hot water main pipe in the semi-circulating pipe network is equipped with return pipe, which can only ensure that the hot water temperature in the main pipe reaches the design temperature, but the hot water will flow out soon after the water distribution point is opened.

Non-circulating pipe network is a hot water pipe network without backwater pipe. In this kind of pipeline, the stored water cooled by non-flow must be discharged before using hot water. for reference only