Hi There, I was going to replace an old radiator for my mum(have done a couple in my own house)but its very old and the two copper pipes feeding are both on the same side, question is the new radiator has flow and return on both sides ,do I cut pipes under floorboards and lengthen them and fit new tails etc, and if so is it possible to join existing copper pipes to the type of plastic piping thats in my house, hope I have explained this properly, thanks in advance for any replies........