The thermostat is based on a Particle Photon which is an easy to use processor module with WiFi. This was initially built to serve as a beer/wine brewing temperature controller but can be used for other applications.
The device is built into a plastic case which is just big enough to accommodate a single gang UK mains socket with a built in USB charger along with Photon and a relay mounted on a small piece of strip-board. The USB charger is used to power the WiFi module but can still provide 1.7 amps with of charging power if needed.
Temperature is sensed via a DS18B20 which is connected via about 1m of cable and built into a stainless steel probe head.
sThe sensed temperature, set point and output status are shown on a small 128 x 64 OLED graphic display. The data is also available using the Particle photon app. I did initially create an IOS app to be able to monitor and control the thermostat but found that it was much easier to use a broker such as BLYNK and use their app.
A small discrete 4/5 way joystick switch is used to adjust the temperature set point and select the display to show Celsius or Fahrenheit. Pressing the switch also toggles between 'thermostat control' and 'thermostat off' functions.
Parts List Particle Photon Joystick Switch 10A Relay OLED Display Temperature probe Logic level FET Resistors