Is there anything that should be done at regular intervals to maintain
a non-sealed domestic gas-fired central heating system? I'm not
concerned about the boiler, as this is checked and maintained by a pro
every year. It's the rest of the system I am concerned about: the
pipework, the rads, the header tank, etc.

Apert from bleeding the rads occasionally, should other maintenance be
doune routinely? Should any kind of chemical be added to the water?
Should the sytem be flushed, and how often?

Thank you,

Drake