Why are there two pipes at one end of the radiator?

Two for inlet pipes and one for return pipe. After the heating is output from the heating company, it should be sent to every household. There are two pipes at one end of the radiator, because two pipes represent the water inlet pipe and one pipe represents return pipe, and the heating used by each household belongs to parallel connection, so there are generally two pipes and one return pipe, which can be controlled layer by layer and avoid affecting too many users when problems occur.