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5251

Warning Heat Pump Z2 not working optimally (high heat curve/hot water setting)

Bosch · Heat Pumps

What does 5251 mean?

Your Heat Pump for zone 2 is reporting that it cannot operate at optimal efficiency because its heat curve or hot water temperature settings are too high, leading to increased energy consumption.

Common Causes

  • The heat curve is set too high for the current ambient conditions.
  • The hot water temperature is set to an unnecessarily high value.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Review your heat curve settings in the Heat Pump's control panel or app and adjust them to a more appropriate level for your comfort and outdoor temperatures.

  2. 2

    Lower your hot water temperature setting to a more economical value, while still ensuring adequate hot water supply.

  3. 3

    Monitor your system's performance and energy consumption after making these adjustments.

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

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Source: Bosch Heat Pumps
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