I have seen and worked with radiator back boxes on the ground floor were pipe are dropped in the middle of the rad. and through a back box and looped around to go back to the manifold. However how is it done on the first floor were pipe are coming to the back box from below? Do they go up the centre and have a elbow then a street elbow inside the back box to bring the pipes back down through the bottom off the back box? Thanks for any insight.