I eventually caved and hired a heating engineer with a Powerflushing machine . This is a high-flow, high-velocity pump with magnets and filters.
Addressing a blocked system requires a tiered approach, ranging from DIY maintenance to professional intervention. blocked central heating pipes
If a system is not properly flushed before commissioning, or if repairs are conducted without cleaning the pipes, flux residues, copper filings, and solder can remain in the system. These solids can lodge in filters or pipe bends, causing immediate or long-term obstructions. I eventually caved and hired a heating engineer
