What tool do i need here ?

[marsaday]

I need to drain down this hot water cylinder, but the drain valve is bigger than a rad one. The square bit inside the valve which you turn to open it up is also big. what tool do i need for this job ?

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Sorry duplicate, computer cocked up.

 

[JayPage]

it looks like a lockshield type drain off. you can use either a 3way key or unspin the locking nut and unwind as per a normal drain cock. Unwinding the locking nut can sometimes case a weep if the drain off is old but then again this can also occur on an old drain cock.

 

[matt1e]

An Isle of man key

 

[Charnwood]

The lockshield looks easily removable (hex at bottom). Give it a try.
That'll expose the square spindle. Mole grips or adjustable spanner.

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Looking at the OPs picture there may not be enough room for a IOM key.