Pipes in plaster
 

Hi all, could someone be so kind to advise me. I need to chase in some pipes into some walls for central heating, as the downstairs have concrete floors, so was thinking off chasing them into the walls, as i dont particulary want them exposed and having to use trucking. Can someone advise me the depth i need to chop in the walls, if i am using 15mm and 22mm piping. If i plaster them in using bonding how much plaster do i need on top of the pipes, as i dont want the plaster to crack because of the pipes expanding and contracting.

Many Thanks