Alex wrote:
there should be a drain cock connected to the cold inlet to the tank down at
the bottom,if not proceeding as you have stated should be ok,think I would
just check that the cold tank in loft has enptied before opening any
connections.Syphoning will take some time to empty I use a sanll inline pump
that connects to a drill works well.

Thanks for the reassurance - job done, with no floods or personal injuries!

David