Junkers Insufficient Heating Output / Circulation Problem

Radiators only partially warm, furnace runs continuously but home does not reach set temperature

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Possible Causes

Air in heating system, Sludged radiators or pipework, Undersized pump, Partially closed valves or balancing issues

How to Fix / Troubleshooting

Safety first: Allow system to cool slightly before bleeding radiators.

  • 1. Bleed radiators: Starting with the highest radiators, bleed air until water flows steadily. Top up system pressure as needed.
  • 2. Check valves: Ensure all radiator and isolation valves are open. Verify that bypass valves are correctly set.
  • 3. Pump speed: Increase pump speed if adjustable and observe improvement.
  • 4. System cleaning: If some radiators remain cold at the bottom, the system may need powerflushing and inhibitor added by a heating professional.
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Repair Difficulty

Easy 2/5

Required Part

Circulation Pump
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