Vokera Poor Heating Circulation / Sludge Build-up

Radiators only get warm at the bottom or some radiators stay cold while boiler runs

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Sludge in radiators and pipework, Blocked Vokera manifold or filter, Pump running at low speed, Balancing valves incorrectly set

How to Fix / Troubleshooting

Safety first: Radiators can be hot; use gloves when bleeding.

  • Bleed radiators: Release trapped air starting from the highest radiators.
  • Check TRVs and valves: Ensure all radiator valves and thermostatic radiator valves are open and not stuck.
  • Engineer tasks:
    • Check pump performance and speed settings.
    • Flush individual radiators or powerflush the system.
    • Clean or replace system filters and strainers.
    • Balance the system by adjusting lockshield valves.

Sludge issues are common in older systems and should be addressed with proper cleaning and inhibitor.

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Repair Difficulty

Medium 3/5

Required Part

Circulating Pump
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