Smart Thermostat: Control your home's heating from anywhere with the ENGO Smart app, or by voice with Amazon Alexa and Google Assistant Wireless Thermostat: The battery-powered E901-WIFI thermostat (2 x AA) connects to its receiver over 868 MHz radio and can be wall mounted or stand on a shelf, away from heat sources and direct sunlight WiFi in the Receiver: 2.4 GHz Wi-Fi is built into the receiver, so no extra gateway hub is needed. Your router must offer a 2.4 GHz network App Features: Schedules with up to 6 periods a day, holiday and party modes, frost mode (5 to 17°C), battery status and offline alerts in the ENGO Smart app Works With Your Heating: The receiver's voltage-free relay (COM/NO, max load 16(5)A) switches boilers, heat pumps, pumps, actuators and ENGO wiring centres. The receiver needs a 230 V supply and fitting by a qualified installer Easy to Use: Clear display and a hidden button panel, so you can program it on the thermostat or in the app. Thermostat 150 x 84 x 22 mm, receiver 96 x 96 x 27 mm