Fault Codes / Daikin / AA

DAI

Daikin AA

High

Altherma — Backup heater (BUH) overheated / BUH power cable not connected.

Daikin AA: Backup heater (BUH) overheated / BUH power cable not connected. This fault noticeably affects operation.

Possible causes

Low flow during BUH operation.
BUH thermal cutout tripped.
BUH supply cable not/loosely connected.

Check steps

Check flow & air purge.
Check BUH thermal cutout & supply cable.

Affected parts

Reserveheizung (BUH)
Thermosicherung

Safety note

230/400V & hot water — caution.

Source: Daikin Altherma 3 Installer Ref. 4P685228-1A (2022.05) §15.4

Reviewed by Anıl Güzeldemir — in the refrigeration machine room since 2006, developer of Enthalio.

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