Daikin Heat Reclaim Ventilator

Daikin Heat Reclaim Ventilator Error Code UC

Troubleshooting guide for the Daikin Heat Reclaim Ventilator system fault UC.

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What It Means

Signals that the address set on a piece of centralized control equipment (central remote controller, schedule timer, or similar) connected to the HRV network conflicts with another device's address, or that the address is otherwise mis-set.

Possible Causes

  • Two or more centralized control devices (or indoor units) sharing the same address on the same network.
  • Address not set, or set incorrectly, during commissioning of the centralized control equipment.
  • Indoor (HRV) unit PCB failing to register or hold its assigned address.
  • Address changed on one controller without updating the corresponding setting on paired equipment.

Not sure which one it is — or if it's none of these? Try ACLogics today.

Disclaimer: This information is for general reference. Error codes can vary by model and production year. Always refer to your machine's specific manual and the information printed on the unit itself.
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Full Diagnosis

Signals that the address set on a piece of centralized control equipment (central remote controller, schedule timer, or similar) connected to the HRV network conflicts with another device's address, or that the address is otherwise mis-set. Because HRVs are typically tied into a building's broader zoning and centralized-control network alongside indoor units, a duplicate address prevents the central controller from reliably identifying and commanding this specific ventilator. When it trips, the affected HRV drops off centralized command and reverts to local operation only. Unlike UE, which is a transmission communication failure between the indoor unit and the centralized control equipment, UC is specifically an address-configuration conflict, not a wiring or signal-loss problem.

All Recorded Causes

Two or more centralized control devices (or indoor units) sharing the same address on the same network Address not set, or set incorrectly, during commissioning of the centralized control equipment Indoor (HRV) unit PCB failing to register or hold its assigned address Address changed on one controller without updating the corresponding setting on paired equipment

Verify Before Replacing Parts

  1. Confirm the exact Daikin model family and heat reclaim ventilator context before acting on a generic code description.
  2. Confirm board LEDs, wiring polarity, and model compatibility before replacing control boards — this Daikin fault points at two or more centralized control devices (or indoor units) sharing the same address on the….
  3. Check for intermittent communication faults caused by connectors, moisture, or damaged harnesses, and rule out address not set, or set incorrectly, during commissioning of the centralized control equip….
  4. After the correction, run the system long enough to confirm the heat reclaim ventilator fault does not return under normal load.

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