Adjustable drain

1. A height-adjustable assembly for a drain, comprising:

a lower portion for use with a waste outlet of the drain, where the lower portion has an inner face and a protrusion extending parallel to and inside of the inner face;

an adjustment portion having an outer face and an inner face, where said outer face is proximate to the inner face of the lower portion, and where the adjustment portion is disposed between the inner face of the lower portion and the protrusion;

an upper portion to receive an attachment for mounting at floor level to cover the assembly, where said upper portion has an inner face including a channel that accepts the protrusion, said upper portion having an outer face proximate to the inner face of the adjustment portion, and where the upper portion is disposed between the inner face of the lower portion and the protrusion; and

adjustment elements on the inner face of the lower portion, both faces of the adjustment portion, and the outer face of the upper portion, where,

when the adjustment portion is rotated, the adjustment elements cooperate to simultaneously adjust a height of the upper and adjustment portions relative to the lower portion, and the protrusion and channel cooperate to rotationally constrain the upper portion as its position relative to the lower portion is adjusted.

2. A height-adjustable assembly as claimed in claim 1 , wherein the locking element of the upper portion includes a flange, lip or channel.

3. A height-adjustable assembly as claimed in claim 1 , wherein the locking element of the lower portion includes a protrusion.

4. A height-adjustable assembly as claimed in claim 1 , wherein the respective locking elements are arranged to slideably engage with one another.

5. A height-adjustable assembly as claimed in claim 1 , wherein the first adjustment element includes a helical thread or ramp to cooperate with a ramp follower disposed on an outer face of the upper portion.

6. A height-adjustable assembly as claimed in claim 1 , wherein the second adjustment element cooperates with a helical ramp or thread disposed on an inner face of the lower portion.

7. A height-adjustable assembly as claimed in claim 1 , wherein the second adjustment element is a protuberance on the outer face of the adjustment portion.

8. A height-adjustable assembly as claimed in claim 5 , wherein the ramp follower disposed on the outer face of the upper portion is a helical thread or ramp.

9. A height-adjustable assembly as claimed in claim 5 , wherein the ramp follower disposed on the outer face of the upper portion is a protuberance.

10. A height-adjustable assembly as claimed in claim 1 , wherein the upper, lower and adjustment portions are circular and fit concentrically within each other.

11. A height-adjustable assembly as claimed in claim 1 , further including a rotation control element to control a position of the adjustment portion to one of multiple discrete positions.

12. A height-adjustable assembly as claimed in claim 11 , wherein the rotation control element includes multiple indentations on a face of a helical ramp or thread disposed on an inner face of the lower portion.

13. A height-adjustable assembly as claimed in claim 12 , wherein the adjustment portion includes a projection to releasably engage with an indentation of the lower portion thereby to bias the adjustment portion in position.

14. A floor drain for a shower, including:

a height-adjustable assembly as claimed in claim 1 connected to a waste outlet for the drain.

15. A floor drain for a shower as claimed in claim 14 , wherein the upper portion includes an attachment mounted at floor level to receive waste water.

16. A method for the telescopic height-adjustment of a drain, including:

providing an upper and a lower portion of a drain assembly, where the upper portion and the lower portion include cooperating elements that rotationally constrains the upper portion relative to the lower portion;

providing an adjustment portion disposed between an upper and lower portion of a drain assembly, the adjustment portion including first and second adjustment elements disposed respectively on inner and outer faces of the adjustment portion; and

rotating the adjustment portion to simultaneously vary a height of the upper and adjustment portions relative to the lower portion and rotationally constrain the upper portion relative to the lower portion.

17. A method as claimed in claim 16 , wherein the upper portion has one degree of freedom.