I live in a house that is 3 years old with an open vented central
heating system.

I am trying to remove a radiator and was looking for the option of not
draining down the system completely.

I was going to use bungs in the feed and vent pipe. When I looked at
the expansion tank there appears to be no vent pipe hanging over the
tank.. The boiler supports a combined a feed vent option but looking on
the internet this looks to be an out of date practice.

Is it still possible to bung the single pipe as you would with the
separate pipes and so not drain the system?