I am re-piping my whole house as I found out it was a one pipe system after buying it. I plan to use plastic speedfit piping and fittings throughout with copper pipe connecting the radiators. My question is this. What is the best technique to connect the copper pipe to the plastic pipe. Can this simply be done using a 90 degrees speedfit connector under the floorboards then a straight copper pipe coming up to the radiator. Any advice would be appreciated. Regards.