"Drake" wrote

Is there anything that should be done at regular intervals to maintain
a non-sealed domestic gas-fired central heating system?

Make sure there is rust inhibitor in sufficient quantity - usually Fernox or
Sentinel product.
Check state of header tank - that it is covered, insulated and has no fungal
growth or debris in.
Check that there is no evidence of pump-over back to the header tank
(visible or audible signs or tank getting hot)
Check that ball float valve works freely and it is set such that the tank
does not overflow.
Make sure all loft pipes are well lagged


Apart from bleeding the rads occasionally, should other maintenance be
done routinely?

Rads should require next to no bleeding once the system has settled (can
take upto a week) after drain/fill.

Should the sytem be flushed, and how often?

If you have recently taken on a system, would certainly advise draining with
gauze over hose discharge to catch crud.
This will give you a good idea of system state.
Hopefully minimal crud will appear - then fill, drain to flush, and re-fill
adding inhibitor.

Should be good for 3-5 years provided no draining or part draining is
carried out.


HTH


Phil