The Taco Mixing Control regulates the supply water temperature to a heating system by simultaneously controlling a boiler and the speed of an injection pump. Based on the outdoor air temperature, the PC705 continuously adjusts the boiler differential to optimize the firing cycles of the boiler, prevent large water temperature swings, and increase the efficiency of the system. As the heating load increases, the Mixing Control speeds up the injection circulator and as the load decreases it slows down the injection circulator. The updated Mixing Control has a liquid crystal display that clearly shows the speed of the variable speed injection pump. It also features warm weather shut down, a maximum supply water temperature setting, and a boiler sensor that can be connected in order to prevent corrosion in the boiler due to flue gas condensation.