Alternatively, if you've got a wet/dry cleaner, you can switch it into
wet mode, turn it on, then loosen the nuts to allow water to flow out
and be instantly sucked sideways.

Call me boring, but I just fit draincock type lockshields, so you just
isolate the rad, attach hose, turn the tap and open the bleed valve.
Radiator drained in 2 minutes and not a drop on the floor.

Christian.