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Poor circulation

Uneven heating/cooling — Poor circulation in heating system

Bosch · Heat Pumps

What does Poor circulation mean?

The flow of heat transfer fluid in your heating system is inadequate, leading to poor and uneven heating or cooling performance from the Heat Pump.

Common Causes

  • Closed or partially closed valves.
  • Blocked radiator thermostats.
  • Air trapped in the system.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Ensure all radiator valves and other heating system valves are fully open.

  2. 2

    Check that all radiator thermostats are set to your desired temperature or fully open.

  3. 3

    If the problem persists, ensure your system is properly vented.

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

Related Faults

5203Alarm Outdoor sensor TL1 faulty5206Alarm Flow sensor T0 faulty5209Alarm Z1 heat transfer fluid out sensor TC1 faulty
Source: Bosch Heat Pumps
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