For existing 17mm UFH installations The coupling is intended for compatible 17mm x 2mm UFH pipe, commonly found in earlier Ambiente systems. Pipe dimensions must be checked before ordering, as current Ambiente P16, T16 and M16 pipes measure 16mm x 2mm and use different couplings. 413 Series manifold connection The coupling connects either end of the UFH loop to a compatible 3/4″ circuit outlet on a 413 Series manifold. Cut the pipe cleanly and square, assemble the fitting correctly and pressure test the completed connection before use.