Turn off heating/hot water, ensure no pumps are running and that system has cooled down
Isolate the filter by turning the two valves to the off position
Drain pressure from canister via the bleed valve or drain valve
Remove lid using spanner provided
Clean magnate off
Replace magnate and lid and tighten hand tight
Re open the isolating valves
Open bleed valve to remove air from canister
Re pressurise system if necessary and check for around lid to ensure a water tight seal has been made