Added a new radiator at the weekend, to a vented system which I had
recently added new inhibitor. New rad is on top floor and I had laid
on the pipework previously, so only a towel rail needed draining,
and the expansion tank. Not wanting to lose the inhibitor in the
expansion tank, I wanted to plug the outlet. Hunted around, and then
hit on the idea of using the plug of silicone which sets in the nozzle
of a silicone gun tube. Blew the plug out backwards with a compressed
air can, and it worked perfectly.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]