Adding the additive / cleaner to my system

tank fed system, drain water below top rad add chemicals to tank, refill bleed rads,combi system get chemical product that you inject into rad through bleed valve,turn rad valves of drain water from rad inject chemicals refit bleed valve open valves and refill,you can also do this with tank fed system.turn valves each side of filter off,drain filter ,remove air bleed valve inject chemicals,refit air cock,or unscrew nut take out magnet and clean pour chemicals in refit magnet,open valves,bleed unit.

Isolate magnetic cleanser at the valves- drain the contents- add inhibitor to it- reseal magnetic cleaner- open valves- bleed magnetic cleaner

I agree with both the engineers who have answered the question both ways work it’s what will be easier for you

On a combi boiler with magna clean you only have to isolate the filter, clean the magnet and fill with inhibitor. Close the filter, open the valves and run the boiler.