What pipe system is this

[alan_fincher]

The outside diameter of most of the common pipe makes is fairly consistent.

Not so at all the internal diameters though, to the extent that inserts that are sloppy fit into some of the thinner walled types simply cannot be forced into some of the thicker wall types.

I quickly discovered it is best to use inserts supplied by the same manufacturer as the pipe.

[stagedamager]

I'm a fan of the polyplumb range both ours are done in it. There wasn't however any isolating valves on any of the systems.....