Build a DIY NEST‑Like Smart Thermostat with Node‑RED on Raspberry Pi

Control your home’s temperature from anywhere with a custom NEST‑style thermostat built on a Raspberry Pi, Node‑RED, and ESPurna firmware.

Project Overview

After juggling multiple work shifts, I found it impossible to manually tweak my old home thermostat each week. I needed a remote solution that let me turn heating on or off before I arrived home—and save energy while I was away.

I chose to replicate the sleek NEST design using an inexpensive ITEAD 1‑CH Wi‑Fi relay and a DHT22 temperature/humidity sensor. The result is a fully‑functional thermostat that can be monitored and controlled from any internet‑connected device.

Installing Software

• Set up Raspbian Stretch on a Raspberry Pi 3.
• Install the Mosquitto MQTT broker on the Pi.
• Install Node‑RED on the Pi.
• Install Atom + PlatformIO on your PC for firmware development.

Hardware Hacking

The ITEAD 1‑CH module is a 5V, 12V Wi‑Fi relay that comes with a proprietary EWeLink firmware. To avoid vendor lock‑in, I replaced that firmware with ESPurna, an open‑source firmware for ESP8266 devices. ESPurna supports custom sensors, making it ideal for adding a DHT22 to the relay.

I soldered the following pins on the PSA‑01 module (the ESP8266 core):

• GND, 3V3, and GPIO14 to the DHT22.
• TX, RX, and GND for flashing the firmware.

Building the Custom Firmware

After installing Atom+PlatformIO, download the latest ESPurna release and extract it. Add the code folder to a new project via File → Add Project Folder.

Edit /config/sensors.h to enable DHT support:
#define DHT_SUPPORT 1 #define DHT_PIN 14

Set env_default = itead-1ch-inching in platformio.ini. Build the project; a successful build ends with a SUCCESS message.

To flash, connect a USB‑to‑Serial adapter to the board, hold the button next to the micro‑USB port while powering on, and watch the LED turn red. Click Upload in PlatformIO; the adapter will blink as the firmware writes to flash.

After flashing, disconnect the adapter, attach the DHT22 (3V3, GND, GPIO14), and power the device with a 5V mobile charger.

The device boots into a soft‑AP named DEVICE_XXXXXX (password: fibonacci). Connect to it and open https://192.168.4.1 to configure Wi‑Fi and security settings.

Configuring the Thermostat

Once connected to your home network, the ESPurna web interface exposes sensor readings, switch status, and a wealth of MQTT, NTP, HTTP, and home‑automation integrations. Configure the MQTT broker details to match the Mosquitto instance on your Raspberry Pi.

Node‑RED will receive sensor data via MQTT and implement your control logic—turning heating on or off based on temperature thresholds or schedules. The flow editor also allows you to create a custom dashboard for remote monitoring.

With the system in place, you can now set desired temperatures, schedule heating, and view real‑time humidity—all from your phone, tablet, or laptop.

Next Steps

Explore advanced features like Amazon Alexa integration, Thingspeak data logging, or automated schedule creation within Node‑RED. The open‑source nature of ESPurna and Node‑RED means you can extend this project indefinitely.

Read More Detail: DIY Virtual Alike NEST Thermostat with Node-RED