Pipes channelled into a wall: plastic or copper?

[AdamW]

I am installing a shower during a bathroom refit. I am channelling the shower feed pipes down from a pump in the loft above.

These pipes are to be channelled into a brick/block wall and then tiled over. I was originally considering copper but am now thinking that plastic would have the advantage of being less heat conductive as well as not corroding. I don't know how it expands and contracts though.

Does anyone have any knowledge on which is better to use in this situation?

 

[breezer]

ours do not go that far but they are copper.

 

[ollski]

copper with no joints.

 

[AdamW]

Thanks for the advice.

I understand why it is a bad idea to fit joints (avoid leaking into walls I reckon). However, to get around this I would have to bend 15mm copper pipe to a radius of about 1.5 inches to 2 inches in order to meet up with my shower mixer. Is that allowable?

I thought of another good reason why a radius would be better than an elbow joint: flow. The tighter you make a turn then the more turbulence you get and thus reduced flow efficiency in the pipe. So, my shower should be that little bit more powerful!