NATURAL GAS Water Heating Thermostat UNI-KITS. The 110 series water heater thermostat Uni-Kit is designed for Universal replacement applications. Some models feature a built in, non cycling Energy Cut-Off (ECO) system to shut off all gas to the heater in case of excessive water temperatures. All models have a 5 1/2" sensing element and vary by inlet and outlet size, shank length, high temperature stop, and regulator type and setting. If the thermostat you are requiring is different from the model illustrated give one of our branches listed below a call with your model’s description.