The universal auto changeover thermostat shall be a Braeburn 5220 number 5220, 3.86” high x 5.11” wide x 1.42” 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 shall retain all user, installer and program settings. The thermostat shall be compatible with low voltage single stage or multi-stage gas, oil, or electric conventional heating or cooling systems with up to two stages of heating and two stages of cooling, and heat pump systems with up to three stages of heating and two stages of cooling. Also compatible with 250Mv – 750Mv millivolt heating only systems and 2 or 3 wire hydronic zone systems. The thermostat shall have a bright blue backlight display, speedbar, separate sub-base and multi-level keypad lockout. Temperature control range shall be between 45° and 90° F (7° and 32° c), accuracy of +/- 1° F (+/- .5° c). operating humidity range between 5% and 95% relative humidity. The thermostat shall include separate installer and user setup modes, residential or commercial 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, auxiliary heat Fossil fuel programming, and compressor power outage protection. A front reset button will return user settings to default values when pressed. Meets energy aware guidelines.