15mm or 22mm pipework for central heating system which and how?

[stanwilcock]

[buildersmate]

Depends entirely on the volume of water you are shoving through there and the length of the pipes (plus the power of the pump, I suppose). For virtually all normal size domestic applications, 15mm is enough for the CH parts of the heating system.

[Dekay]

When I did my heating (2 bed, upstairs downstairs), I ran 22mm to central positions both upstairs and down, then stuck manifolds on each end, and 10mm insulated pipe to each radiator. That was for a combi boiler running 8 radiators. hope that helps..

[buildersmate]

That is true. I thought he was talking about down to the rads themselves.