NIBE 2

High

F-Serie — Alarm '2' (sensor fault BT2) is the heating medium SUPPLY (flow/Vorlauf) sensor, not the return (that is BT3). Additional heating is blocked; system falls back to condenser-out sensor (BT11).

NIBE 2: Alarm '2' (sensor fault BT2) is the heating medium SUPPLY (flow/Vorlauf) sensor, not the return (that is BT3). Additional heating is blocked; system falls back to condenser-out sensor (BT11). This fault noticeably affects operation.

Possible causes

BT2 not connected/defective.

Check steps

Check BT2 sensor.

Affected parts

Vorlauf-Fühler BT2

Safety note

Hot water — scald risk.

Source: NIBE Energy Systems official Alarm List (Version 1747-1) + ECS 40/41 Fühlerkonvention (installer.nibe.eu): BT2=Vorlauf/supply, BT3=Rücklauf/return. DÜZELTİLDİ 2026-07-14 (içerik-denetimi): önceki içerik BT2'yi yanlışlıkla 'Rücklauf/return' diyordu — resmi kaynakla GİDİŞ/Vorlauf olarak düzeltildi.

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

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