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24VAC thermostat add-on

Overview

This add-on turns your CTRL ONE into a fully-featured smart thermostat, capable of controlling simple 3-wire heating systems such as furnaces and in-floor heating. An isolated power supply runs the CTRL ONE safely from your heating system 24 V AC power, allowing it to be wall-mounted to standard 60 mm wall receptacles.

With the add-on installed, the CTRL ONE exposes a thermostat controller that can be managed from the touchscreen or directly from Home Assistant - with no cloud or separate app required. Use the full power of Home Assistant to create automations, relying on other sensors around the home: for example, turn the heating down when nobody is at home using the home/away capability.

The CTRL ONE is a fully standalone thermostat, and will continue functioning if the WiFi cuts out or Home Assistant goes down. With the onboard SCD40 temperature sensor you can set the temperature setpoint directly on the device.

ESPHome configuration

The CTRL ONE must be reconfigured to add the thermostat functionality before use. The add-on defines a switch on the add-on pin, wired to an ESPHome thermostat climate component that uses the onboard SCD40 as its temperature sensor. Import it into your ESPHome configuration with a packages: entry:

packages:
  thermostat:
    refresh: 4h
    url: https://codeberg.org/elvinhome/ctrl-one
    files:
      - esphome/addons/addon-24vac-thermostat.yaml

See the ESPHome configuration page for how packages work, or view the file directly in the Codeberg repository.

Specifications

Input power

3 V - 28 V AC, 4.5 V - 40 V DC

Thermostat terminal maximum ratings

Up to 1 A continuous current, 8 A peak current

Thermostat terminal switching capability

AC only - this add-on is unable to switch DC loads

Installation notes

Do not use the USB port while the CTRL ONE is powered via this add-on. While every effort has been made to ensure safety, we are not responsible for damage caused to the CTRL ONE or connected devices if the USB port is used while powered via the 24VAC add-on.

This add-on protrudes out of the rear of the CTRL ONE and is intended for applications where the device is mounted to a 60 mm recessed wall mount. It will not work with the stand included with the CTRL ONE.

See the product page for ordering information.