Worcester Bosch Poor Circulation / Sludged System

Boiler provides hot water but radiators only get warm at the bottom or some radiators stay cold.

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.

Possible Causes

Sludge build-up in radiators, Blocked return pipework, Partially blocked plate or primary heat exchanger, Pump running at low speed

Safety first: Let the system cool before bleeding or removing any components.

Bleed radiators: Remove air from all radiators, especially those that are cold at the top.
Check TRVs: Ensure thermostatic radiator valves are not stuck closed; gently tap the valve body and ensure the pin moves freely.
Clean system filter: If you have a magnetic filter, clean it thoroughly.
Engineer tasks: A heating engineer should assess for powerflushing, check pump performance, and clean or replace blocked components.

Medium 3/5

System Filter / Magnetic Filter

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