Azel D-508F: NON-PROGRAMMABLE DIGITAL SLAB SENSING THERMOSTAT FOR HYDRONIC RADIANT FLOOR HEATING Easy-to-Read Digital Multi-Display with backlit which provides constant readout of two sensor temperatures(eg. ambient and floor) and setpoint simultaneously, functional status and control settings. Three temperature control modes: A Mode : controls ambient temperature F Mode : controls floor temperature. Also displays current ambient temperature. AF Mode: controls the ambient temperature and maintains the floor temperature within the desired minimum limit for floor warming and maximum limit for protecting floor coverings. Also, displays current floor temperature.