Run 22mm copper flow and return pipes 2 metres from the boiler (situated ground floor), then split the flow pipe into two 22mm Speedfit plastic pipes. One of these pipes will go to a 4 outlet flow manifold on the ground floor, and the other to a 4 outlet flow manifold upstairs. Then split the return pipe in the same way, with a return manifold downstairs and one upstairs. (N.B. Each manifold has 4 X 10mm outlets)

The downstairs manifolds will feed 4 small to medium rads. The upstairs manifolds will feed 3 medium rads and a towel rail.

Hope this makes sense. Will it all work? Is there anything else to consider, and do I need a bypass? Many thanks.