Adjustable Water Pump Flanges are used to connect a hydronic system pump is connected to a water supply pipe. The pipe diameters, working temperatures, and other characteristics vary. The radiators coolant is forced by the water pump through the engines coolant system and back to the radiator. Adjustable Water Pump Flanges are very effective and safe to use. They are easy to install and simple to use. The quantity of air entering a pump from the hot water cylinder is controlled by a flange.