Troubleshooting

Use this chapter when a message appears or a procedure does not complete. For device details to include with a support request, see About and Details.

No connection to the Serin Controller

Serin Link can lose its connection to the Serin Controller. For example, a power failure at the heat pump or a tripped circuit breaker can cause this condition. Serin Link then shows a notice across the full screen:

Tap the notice to read the explanation and the instructions:

Tap Dismiss to return to the home screen. A red Offline status label stays above the target temperature. The last measurements stay on the screen, but they become dim because they are no longer current.

Tap the Offline status label to open the explanation again. Normal operation starts again automatically as soon as Serin Link can exchange data with the Serin Controller again:

Heat pump, Wi-Fi, and synchronization problems

Condition	What failed and what to do
Link offline / No link	The wireless path between Link and the controller is unavailable. Check controller power. Reduce the distance if necessary.
Heat pump offline / CN105 Not connected	The controller cannot exchange data with the heat pump over the CN105 cable. Check its connection using the installation instructions.
Communication-error count	The controller reports serial communication errors. Check whether the count continues to increase. Record the count for support.
Wi-Fi Offline	The controller has no home network connection. Check the router and network details under Settings → Wi-Fi.
Syncing	Link is waiting for current controller state. Wait before changing controls. If it persists, check Settings → Link.

Wi-Fi loss and controller radio loss are different conditions. Home apps and network functions need Wi-Fi. Local Link control can continue without Wi-Fi when its controller radio connection and CN105 connection work.

To inspect serial status, open Settings → Advanced → Heat Pump. Use About → Details for more diagnostics. Follow the CN105 installation instructions before handling connections. Contact support if communication does not recover.

Change pending

CHANGE PENDING means that Link sent a command and awaits confirmation. Wait for the controller to report the result. Tap the label to read the explanation. Tap Open Settings to inspect the reported state if the message persists. Do not treat the displayed target as confirmation that the heat pump applied the command.

Heat pump fault

1. Tap HEAT PUMP FAULT on the home screen.
2. Record the reported fault code, if one is available.
3. Tap Open Settings to inspect the controller’s status.
4. Give the code and symptoms to the heat pump service technician.

Link cannot clear a heat pump fault. The warning disappears if the heat pump recovers. A fault code is different from a lost Link wireless connection.

Low sensor battery

When the battery in a battery-powered room sensor is low, an amber LOW BATTERY label shows at the bottom of the home screen. This label is a warning, not an emergency. Heating and cooling continue as usual:

Tap the LOW BATTERY label to read the explanation. Tap Dismiss 24h to hide the warning for 24 hours:

Pairing recovery

If Pairing failed appears:

1. Check that the intended controller has power.
2. Open its pairing window again.
3. Tap Retry on Serin Link.
4. Keep the pairing window open until the search completes.

If Link already has zones, tap Back to return to Settings. The existing zones remain available. During a search, tap Cancel or hold the knob to stop searching.

Zone limit reached means that Link cannot add another zone. Tap Back. Forget one zone before you add another. Link supports up to seven zones.

Controller reset means that the controller no longer has the expected pairing. Use Zones, when available, to select the affected zone. Otherwise, tap Back. Check the zone name under Settings → Link. Forget that zone. Then pair Link with that controller again.

Unavailable sensor readings

Message	Meaning and action
Reading is stale	The controller reports that the measurement is too old. Check sensor power and range. Select another available source if necessary.
No reading available	The controller has no usable reading from this source. Check its configuration and power. Select another available source.
No sensors available	The source list is empty. Select Back. Check the controller and its sensor configuration.
Sensor no longer available	The highlighted source disappeared from the list. Highlight another source, then push the knob.
Controller does not offer source selection	This controller does not report source-selection support. Use its firmware configuration instructions.

A stale or missing reading does not prove that the controller changed sources. Fallback depends on the controller firmware. Check its Room Sensor status and instructions before you rely on automatic fallback.

Retry, cancel, or return later

To leave an active session, see Cancel Wi-Fi setup.

If The controller didn’t respond. appears after approximately 15 seconds:

1. Check controller power and the Link connection.
2. Push the knob to retry the setup request.
3. Wait for the hotspot QR code.

The network-change QR screen returns home after approximately nine minutes. Initial setup QR screens, home-pairing screens, and web QR screens return home after approximately ten minutes. Reopen Settings → Wi-Fi, HomeKit, or Matter as applicable. Check the current state before you start again.

Pairing status and missing codes

Status	Meaning and action
Paired	The controller reports an existing home pairing. Normal Settings entry does not reopen the setup QR screen.
Ready to pair	The controller reports no home pairing. Push the knob to display its code when the Link connection is online.
No link	Link cannot reach the controller. Restore that connection before you attempt home pairing.
Code appears without a QR image	Use manual code entry, or wait for the controller to supply QR data.
--- instead of a code	No usable code is available yet. Check the controller connection and its web interface. Do not enter the dashes.
HomeKit, Matter, and Home are absent	The controller does not advertise home-pairing support to Link. Follow its firmware instructions.

The setting’s name comes from the controller’s pairing data. It can be HomeKit, Matter, or Home. Paired does not prove that the phone, home hub, or controller Wi-Fi connection is currently working.

Link has no general action to remove a home pairing. Forget zone and Reset Link remove Link data, not the controller’s HomeKit or Matter pairing.

Update failure

Failed includes a reason. Unit unreachable means that Link could not obtain controller access. WiFi failed means that Link could not connect for the update. Update check failed or Download failed means that the update transfer failed. Bad manifest means that the update information could not be used. Link busy — retry means that an update task could not start.

1. Record the failure message.
2. Tap Done, or push the knob to dismiss it.
3. Check controller power, Wi-Fi, and internet access.
4. Return to About → Details → Update to retry.
5. Contact support if the failure continues.

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Serin Link and Serin Controller are part of the Serin system. The product user interface generates the images in this manual. If your screen looks slightly different, your firmware version can be different from the version that this manual describes.