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Daikin · Heat pumps · Daikin Altherma 3 R F (split heat pump, R32)

AA-01Backup heater overheated or BUH power cable not connected

Name in the manufacturer's documentation (service manual): Backup heater overheated or BUH power cable not connected[1]

In plain words (editorial)

The backup heater overheated or its power cable is not connected. The manual says to check that the backup heater circuit breaker is on, and – if the thermal protector activated – to check water pressure and air in the system before pressing the reset button in the switch box. It names air in the system and too low water pressure as causes.

When to call a service technician: If the problem persists, the manual says to contact your dealer.

✎ editorial – written from the cited sources, not a manufacturer statement. Status: draft.

The Polish page has more detail (plain-language explanation, safe checks, guides): Read in Polish →

Sources

Every statement has a footnote to the document and PDF page. “Quote verified” means the quote was found automatically in the text of that page.

  1. [1] Daikin Altherma 3 R F – ERGA04~08E + EHVH/X04+08S18+23E – Installer reference guide (4P629086-1D (2024.04)) , p. 254 official manufacturer document quote verified AA-01 Backup heater overheated or BUH power cable
  2. [2] Daikin Altherma 3 R F – ERGA04~08E + EHVH/X04+08S18+23E – Installer reference guide (4P629086-1D (2024.04)) , p. 251 official manufacturer document quote verified Whether there is air in the system
  3. [3] Daikin Altherma 3 R F – ERGA04~08E + EHVH/X04+08S18+23E – Installer reference guide (4P629086-1D (2024.04)) , p. 251 official manufacturer document quote verified - The water pressure
  4. [4] Daikin Altherma 3 R F – ERGA04~08E + EHVH/X04+08S18+23E – Installer reference guide (4P629086-1D (2024.04)) , p. 251 official manufacturer document quote verified The backup heater overcurrent circuit breaker is on. If not, turn it back on.
  5. [5] Daikin Altherma 3 R F – ERGA04~08E + EHVH/X04+08S18+23E – Installer reference guide (4P629086-1D (2024.04)) , p. 251 official manufacturer document quote verified the reset button in the switch box:
  6. [6] Daikin Altherma 3 R F – ERGA04~08E + EHVH/X04+08S18+23E – Installer reference guide (4P629086-1D (2024.04)) , p. 248 official manufacturer document quote verified The power supply to the backup heater is correctly wired.
  7. [7] Daikin Altherma 3 R F – ERGA04~08E + EHVH/X04+08S18+23E – Installer reference guide (4P629086-1D (2024.04)) , p. 248 official manufacturer document quote verified The backup heater contactors are NOT broken.
  8. [8] Daikin Altherma 3 R F – ERGA04~08E + EHVH/X04+08S18+23E – Installer reference guide (4P629086-1D (2024.04)) , p. 248 official manufacturer document quote verified If the problem persists, contact your