Serin Link controls temperature, mode and airflow through a Serin Controller at your heat pump, or a compatible ESPHome climate device. Its direct wireless connection works without home Wi-Fi. One Serin Link supports up to seven rooms, called zones, with a controller at each indoor unit.

Place Serin Link near a USB-C power source; it has no battery. Turn the knob to change temperature, or press it for mode and fan controls.

Dashed: wireless. Solid: CN105 cable.

On this page

Download the one-page Serin Link quick start (PDF).

Already paired? Go to Temperature, modes and airflow.

Before you start

• Power Serin Link and keep it within wireless range of the controller. An assembled Serin Link has its firmware installed.
• Set up a compatible Serin Controller or ESPHome climate device. A Controller added to a Serin Link order ships unflashed. For app control, complete Controller setup. For local control alone, follow Using Serin Link without a smart-home app.
• The standard browser-installed ESPHome build includes Serin Link support. With the YAML generator, enable Connect a Serin Link and install the configuration before pairing.

Both NanoC6 and AtomS3 Lite support Serin Link with the standard Matter-compatible controller firmware.

Pair and check control

1. Open the controller’s pairing window:
   • With HomeKit-compatible or Matter-compatible firmware, select Pair in the web interface’s Link card.
   • With ESPHome, select Pair Serin Link in Home Assistant or the enabled web interface.
2. On Serin Link’s ready screen, tap Pair or push the knob. Keep the controller’s pairing window open until Serin Link reports Paired and restarts.
3. Check that Serin Link shows the room temperature. Turn the knob to change the target temperature, then wait for the controller to confirm the change.

If the heat pump does not accept the change, follow Pairing recovery. See First power-on and pairing for screenshots and cancellation.

Using Link without a smart-home app

For local control without a home app, hub, or home Wi-Fi, install the free, open-source HomeKit-compatible firmware on the Serin Controller. No Apple device is needed. An assembled Serin Link already has its own firmware.

1. Connect the Controller to a computer with a USB data cable. Leave its CN105 cable disconnected. Open the Controller flash tool in Chrome, Edge, or Brave. Select Apple Home and install the firmware.
2. If the tool asks for Wi-Fi details, select Skip and use the backup setup network. You do not need to join that network or add the Controller to an app. Leave the Controller powered over USB for pairing.
3. Power Serin Link with its included cable and charger. Keep it near the Controller.
4. On the new Controller, hold its button until the light turns purple, after about two seconds. Release before seven seconds to open pairing. This button procedure is for a Controller with no paired Serin Link; on an already paired Controller, the same hold removes its Serin Link pairings.
5. On Serin Link’s ready screen, tap Pair or push the knob. Wait for Paired and the restart. A heat-pump connection warning is expected while the Controller’s CN105 cable is disconnected.
6. Disconnect the Controller’s USB cable. Turn off the indoor unit at its breaker, then follow the Controller installation guide. Replace the cover before restoring power.
7. Wait for Serin Link to show current room information. Turn its knob to change the target temperature and confirm that the indoor unit responds.

Connect the Controller to Wi-Fi for browser controls or wireless updates. If Serin Link offers Wi-Fi setup, keep the knob pushed on that offer until the confirmation arc completes to hide it. You can set up Wi-Fi later.

Continue setup

• Use temperature, mode and airflow controls.
• Add another room.
• Choose a room temperature sensor.
• Set display brightness and control locking.
• Connect the controller to Wi-Fi for network functions and home apps.