Constant-pressure water replenishing device for expansion tank

The utility model provides a constant-pressure water replenishing device for an expansion tank. Comprising supporting legs, an outer tank body is welded to the upper portions of the supporting legs, a barometer is installed on the outer wall of the outer tank body, a water inlet pipe is installed on the portion, located on one side of the barometer, of the outer wall of the outer tank body, a water outlet pipe is installed on the outer wall of a water pump, a cart is installed at the bottom of the water pump, and two first connecting bases are welded to the upper surface of the cart; and a translation mechanism is mounted on the upper surface of the cart and located on one side of the water tank. According to the constant-pressure water replenishing device for the expansion tank, when the water tank needs to be cleaned, a user can rotate the gear on the second connecting base, the gear is meshed with the rack, so that when the user rotates the gear, the gear can be driven to control the push block to do trans