D-28F digital thermostat is specifically designed for Radiant Floor Heating Systems. It is so flexible that it can be used to control either air temperature (A Mode} or floor temperature (F Mode) or a combination of air temperature with floor temperature limits(AF Mode). An auxiliary remote sensor is provided to measure slab temperature in order to control the floor temperature within desired maximum and minimum limits. = Display Format: Liquid Crystal Display{LCD} = Operate power : Battery 1.