radiator and drainage point

[zam60]

need to replace radiator due to hole but not sure if need to drain system because drainage the point is under radiator have tried to close in and out vent but water still flowing out of pin hole in radiator

 

[hi-spec plumbing heating]

shut the rad valves each end then slacken one of the nuts on the end of rad and drain the rad.
no need to drain whole system

 

[JohnD]

if you have closed the valves at both ends and it is still dripping, then either one or more of the valves is not closing properly; or else the water remaining in the rad is still dripping out.

You may need a small adjustable spanner on the spindle if you can't turn them off by hand on the plastic knob (take the knob off first)

Tie up the ball valve in the feed & expansion tank to prevent an unending supply of water to the leak (and turn off your boiler until you can refill it)

If you have already got the new radiator that will hopefully not be long.

What floor is the faulty radiator on; and where is the drain valve?

If the valves are not sealing properly you might think about fitting new ones. If you end up having to drain anyway, this is a convenient time to fit a TRV.