ESP32/ESP8266 Thermostat Shield

€ 14.50

The DIYLESS ESP32/ESP8266 Thermostat Shield is a low-cost and easy-to-use device that allows you to build your own OpenTherm-compatible thermostat.


Shipping from the EU.

ESP8266 is not included. Please check PARTS LIST tab

Think out of the box with
ESP8266/ESP32 OpenTherm Thermostat Shield

ESP8266 Thermostat Shield can be used for building your own DIY OpenTherm WiFi Thermostat with remote control for a cheap price and without any monthly costs. It supports all OpenTherm compatible boilers and can be integrated into your favorite home automation system.

ESP8266 OpenTherm Thermostat Shield

Key Features

While using Smart OpenTherm Thermostat you will get the following advantages:

Remote control

Control at any time, from anywhere remotely via a Wi-Fi connection your home's thermostat settings through your smartphone, tablet or personal computer. Also it can be integrated into your smart home automation system like Home Assistant, Tasmota, Domoticz etc.

Energy savings

Smart thermostat can save you money on energy bills.
OpenTherm thermostat together with modulating boiler use more or less gas when it's appropriate rather than by cycling it On and Off, to be more efficient while keeping you comfortable.
The important difference here is that the boiler will run for longer periods but producing water at lower temperatures resulting in less gas being used and maximizing the time spent in the higher efficiency condensing mode.


Smart thermostat it is about comfort.
ON/Off modulating heating controls adjust the average water temperature within the heating system by cycling your boiler On and Off periodically.
That is why set point is not accurately controlled, so overshoots (unnecessary overheating) and undershoots is a common problem of such kind of thermostats.
This can feel uncomfortable and normally leads to residents setting the thermostat higher than required.

OpenTherm Thermostat

More Features

With OpenTherm Thermostat Shield you have complete freedom to customize and implement any functionality you want.

OpenTherm Boiler Connection

Easy Assembly

Just solder corresponding headers, screw terminal block and DS18B20 temperature sensor.
Stack WeMos D1 Mini.
Connect shield to a boiler using 2 wires.

ESP8266/ESP32 Compatibility

Thermostat shield is designed to stack WeMos D1 mini or WeMos D1 MINI ESP32 board.
In general, you can use it with all types of microcontrollers.

Boilers Support

OpenTherm Thermostat Shield is compatible with all boiler those have OpenTherm protocol support.

OpenTherm Protocol Compatibility

OpenTherm Thermostat Shield is compatible wth all OpenTherm Protocol versions from the earliest to the latest.

Arduino OpenTherm Library

Easy to use and extend Arduino OpenTherm Library for HVAC system control communication with basic examples. Source code in GitHub repository

Usage samples & integrations

Check our blog for samples and integrations with most popular Home Automation systems, like Home Assistant, Tasmota, Domoticz... Some list below.

Home Automation Integrations

We have a number of Home Automation integration examples which allows automation, remote control, monitoring and so on...


Basic OpenTherm Sample

Is a good starting point to understand how OpenTherm Library works and ensure right connection of OpenTherm Master shield.


ESP32 Wifi Thermostat

Is a simple thermostat with a web interface, is controlled via wifi from any browser within your network.


Blynk OpenTherm Thermostat

Enables remote control via your smartphone over the internet with a few simple steps.

Home Assistant

Home Assistant OpenTherm Thermostat

Is a complex home automation solution which allows you fine tuning of automation according to your needs.


Domoticz OpenTherm Thermostat

Is a very light weight home automation system that lets you monitor and configure miscellaneous devices, including lights, switches, various sensors/meters like temperature, rainfall, wind, ultraviolet (UV) radiation, electricity usage/production, gas consumption, water consumption and many more. Notifications/alerts can be sent to any mobile device.


Tasmota OpenTherm Thermostat

Simplifies further integration into home automation systems or can act as an automation tool itself.

ESP32 WiFi Thermostat

To connect OpenTherm Thermostat Shield you'll need a pair of wires and a micro-USB cable with wall charger. Connect B1/B2 terminals to the boiler (polarity does not matter) with any 2-wire cable or twisted pair. Plug in micro-USB cable to the Wemos and wall charger. Now OT thermostat should be enabled and communicating to the boiler.

Component Pieces
Master OpenTherm Shield 1
Temperature sensor DS18B20 1
Stackable Female Header 2.54mm 8Pin 11mm Length 2
Stackable Female Header 2.54mm 8Pin 3mm Length 2
Single Row Male 2.54mm Breakable Pin Header Connector 8Pin 2
Screw Terminal Block Connector KF128-2P 3.81mm 2Pin 1
Shipping method Estimated Time Fees
12-15 days €5.5