Whilst removing a radiator today I think the builders who did an extension recently at this customers house have used a plastic elbow in the concrete floor. There's copper rising out of the floor but I can twist the pipe which probably means it's a speedfit fitting. Does anyone know what the manufacturers of plastic fittings say about burring their fittings in concrete? Personally I'd have used copper and wrapped tape around it as concrete can attack copper over a period of time.