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8H-03

8H-03 — Overheating water circuit (thermostat)

Daikin · ASHP Error Codes

What does 8H-03 mean?

The main water circuit is overheating, and the problem is linked to the thermostat.

Common Causes

  • Faulty thermostat controlling the main water circuit
  • Temperature sensor failure
  • Overload in the system

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Inspect the thermostat and its wiring.

  2. 2

    Ensure the thermostat is receiving accurate temperature feedback.

  3. 3

    Power cycle the unit to reset.

  4. 4

    Professional assistance is recommended for thermostat replacement.

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

7H-017H-01 — Water flow problem7H-047H-04 — Water flow problem during domestic hot water production7H-057H-05 — Water flow problem during heating/sampling
Source: Daikin ASHP Error Codes
Open Manual (Page 2)Search more codes in this manual