I'm looking for thoughts on how best to secure the mixer to breeze block wall. Current the mixer is held in place by the copper pipes which only one is really secured to the wall. I was thinking of some plywood screwed to the wall as a support for the mixer. Something similar for the outlet elbow also. I have a 90degree fitting with a push fit water connection and 1/2" for the elbow. Where should I look for 1/2" nipple extension and 1/2" coupling? Seem to be a bit difficult to find online. Back of current shower mixer https://www.dropbox.com/s/xdwrc0ecgdpocic/IMG_8237.JPG Back of current elbow https://www.dropbox.com/s/b36h55uwz3pevy9/IMG_8239.JPG Rube Goldberg plumbing I'm dealing with (none of the wires are live, electrician disconnected them already) https://www.dropbox.com/s/fbkufvu5sijdbu4/IMG_8238.JPG Mixer we're using https://images.victorianplumbing.co.uk/images/pdf/CSV12.pdf Shower slide rail with elbow https://images.victorianplumbing.co.uk/images/PDF/TRAF-RK.pdf Thank you for suggestions.
Based on how I interpret the photos you’ve posted, I would suggest that you strip the plaster (or whatever covers the blockwork on the shower side of the wall) and replace with Aquapanel boards, glued and screwed to the blockwork. Using the mounting plate and screws provided with your new mixer, simply attach it to the aquapanel to fix it in place once you have run the pipework through the Aquapanel via normal elbows. The pipework will no longer need to provide any support for the valve and you can make the connections in any way that suits you best. It maybe a good idea to add a scrap of plywood 100mm x 100mm behind the aquapanel to take the screws for the mixer backplate if the hole in the blockwork allows.
Sorry forgot to mention we want to recess the mixer. It has a faceplate for this purpose and suggests recessing 53-68mm from surface. Attention: If you choose the concealed model. The valve will come with valve cover plate, not the small nut cover plate. You should make a recess in the wall to house the valve. The depth of the recess should be 53mm to 68mm below the finished wall surface to fit the cover plate correctly.