The Braeburn 4235 is a universal auto changeover thermostat with4235, 4.25” high x 5.12” wide x 1” deep, powered with either 24 Volt AC or with two “AA” Alkaline batteries (3.0 Volt DC). In the event of a power failure, the unit will retain all user, installer and program settings. The thermostat shall be compatible with low voltage single or multistage gas, oil, or electric heating or cooling systems and single or multistage heat pumps with auxiliary heat. Also compatible with 250mv – 750mv millivolt heating only systems and 2 or 3 wire hydronic zone systems. The thermostat will have an adjustable bright blue backlight display, separate sub-base and multi-level keypad lockout. Temperature control range is between 45 and 90 F (7 and 32 C), accuracy of /- 1 F ( /- .5 C) and operating humidity range between 5% and 95% relative humidity. The thermostat includes separate installer and user setup modes, permanent non-volatile memory to retain user settings, filter, UV and humidifier pad check monitor, adaptive recovery mode (ARM™), programmable fan mode, residual cooling fan delay, indoor or outdoor remote sensor capability and multi-function dry contact input. Thermostat can be used to control an external humidifier or dehumidifier. The cooling system can also be used to reduce humidity.