The Robertshaw® 110 Series gas water heater valve was first manufactured for the O.E.M. market in 1955. For the last 50 years, the 110 series has been the definitive gas water heater valve. Over the years, minor product improvements were incorporated, but the valves have remained basically the same. The 110 Series Water Heater Thermostat Uni-Kit® and Commercial Water Heater Thermostat Uni-Kits® were designed for universal replacement applications. All models feature built-in, non-cycling Energy Cut-Off (ECO) system to shut off all gas to the water heater in case of excessive water temperatures. If an ECO has detected an over-temperature condition and has opened, the control will not function and a new replacement will be required. All domestic and RV models have a 160°F temperature high stop. All commercial models have a 180°F temperature high stop. 5-1/2" sensing element.