Recognise the true value of magnetic filters!

1. It relies entirely on the standard heating system circulation pump to drive dirt/sludge towards the magnetic filter, and the system may be quite lengthy. The circulation pump's design flow rate is relatively slow, causing larger dirt/sludge particles to detach during circulation and accumulate in low-flow areas such as the bottom of radiators/underfloor heating or at bends. Scientific research has demonstrated a direct correlation between the volume of dirt/sludge expelled from water systems and the velocity of the flushing water flow. Higher velocities yield superior results. Without high flow rates, heavier, larger dirt/sludge particles lack the momentum to move and will only continue to settle and accumulate.

2. Regarding corrosion debris, the circulation pump itself acts as a ‘magnet’ that continuously attracts and traps such particles. The magnetic field generated by the motor draws debris accumulated within the pump passages and impeller, significantly reducing the already sluggish flow rate. This issue has intensified with the market introduction of new high-efficiency circulation pumps. Most circulation pumps now employ permanent magnet motors, which generate magnetic fields continuously—not just during operation.

Users and manufacturers are increasingly recognising potential issues with circulation pumps installed in systems containing corrosive debris. New wall-hung boilers/boiler systems (using permanent magnet motors) demand higher system cleanliness. Within systems heavily laden with corrosive particles, the pump rotor gradually accumulates a layer of magnetic debris, significantly reducing system and pump efficiency. Corrosive particles can also cause rotor seizure. Therefore, thorough system flushing is essential after installing a new circulation pump, let alone when installing a new wall-hung boiler/heating system.

3. Within heating systems, pumps propel water in a single direction. This causes low-flow areas—typically at the bottom of underfloor heating pipes/radiators—to accumulate dirt/sludge that obstructs water flow. Unless flow direction can be rapidly reversed, this sediment remains stagnant.

4. Without the powerful flow rates generated by a turbulent cleaner, magnetic filters can only capture debris/sludge within centimetres of their proximity. Accumulated deposits will remain stationary within radiators and pipework, progressively diminishing system efficiency. Silt and corrosion products complicate matters further. Sludge/sediment comprises a mixture of magnetic and non-magnetic debris. Engineers must recognise that non-magnetic particles will not be captured by magnetic filters and will continue circulating unless flushed from the system by high flow rates.

5. Within central heating systems, a temporary (or permanent) magnetic filter will have no effect on flushing and removing existing dirt/sludge from the primary water side of plate heat exchangers. Consequently, plate heat exchangers require separate flushing. Particles smaller than 15gm are sufficient to obstruct flow and cause a boiler lockout!