No, mixing valves will not be required. The Electron series water heaters will be ASSE – 1082 compliant. The ASSE-1082 standard equates Electron Series Tankless Heaters to thermostatic mixing valves and temperature-limiting devices. Also, the Electron can control water temperature within the tolerances of ASSE 1017 / 1071 standards, and thus, no mixing valves when using Electron units.