Constant-pressure water supplement unit having swelling water collecting and metering functions

The utility model discloses a constant-pressure water supplement unit having swelling water collecting and metering functions and relates to the technical field of constant-pressure water supplement units. The constant-pressure water supplement unit is mainly composed of a cement foundation, a constant-pressure expansion tank and a constant-pressure water supplement unit body, and a connecting pipe is installed between the constant-pressure expansion tank and the constant-pressure water supplement unit body. The constant-pressure water supplement unit having the swelling water collecting and metering functions is a constant-pressure water supplement and exhaust unit used for performing pressure stabilizing, automatic water supplement and swelling water collecting and metering on a heating and ventilating system or a technological circulating water system, so that the pressure of the closed circulating water system is stabilized, and water resources and energy are saved.