I ran in pipes for 3 rads in an extension a while back and am only now fitting the rads due to a big delay from the supplier of the vertical rads.
I branched off from the existing heating system and ran 2 pipes to the furthest rad, with branches along the way for the 2 other rads. I have the pipes centred correctly and coming out from the wall at the right spots but am not sure which ones are the feed and which are the returns?. How important is this and what is the best way for figuring out which is which?