Floor heating thermostats Model description AE-Y309-A:This model is designed to control a room’s ambient temperature with one temperature sensor located in the control module. AE-Y309-AF:This model is designed to use a floor sensor to control the room temperature. The model has two temperature sensors. One is a built-in sensor inside the thermostat, controls the ambient temperature.The other one is installed in the floor (and connected to the power base), limits the floor temperature(the default setting of this limit is 28?). AE-Y309-F:This model is designed to control floor heating systems. It has one temperature sensor installed in the floor (sensor is connected to the power base).