Water Heater Thermostatic Mixing ValveThe Honeywell Thermostatic Mixing Valve helps you set your water heater to 120 Degree F to help reduce the threat of bacteria growth. The valve uses a mixing action to help prevent scalding. Helps prevent bacteria growth by helping you to set your water heater at 120 Degree F Helps prevent scalding by reducing the temperature at the faucet Helps extend the capacity of your existing hot water heater 3 4 in. sweat union Meets IAPMO, ASSE 1016 and 1017