In vertical stacks surface tension makes flowing water cling to the perimeter of the pipe. The supply can then be coaxial like I think you are saying. This is

In vertical stacks surface tension makes flowing water cling to the perimeter of the pipe. The supply can then be coaxial like I think you are saying. This is one product (linked below) like this although I think plastic would be fine if a little less thermal conductivity and less expensive than this much copper. https://renewability.com/ https://renewability.com/