Start from the operating temperature
For radiator circuits and domestic hot water, choose PEX-AL-PEX or PE-RT/AL/PE-RT, with catalogue references of 95 °C and 10 bar. These maxima are not a combined continuous-duty rating; confirm the application class and full temperature-pressure profile. For cold water and compressed air, PE-AL-PE is the economical option. For exposed risers where a rigid pipe is easier to support, choose PP-R/AL/PP-R.
Size the pipe for flow, not habit
Floor-heating loops are usually 16 × 2.0 or 20 × 2.0 mm. Radiator branches run in 16–20 mm, distribution lines in 25–32 mm, and mains or risers in 40–75 mm straight lengths.
Pick the joining system early
PEX, PE-RT and PE multilayer pipes are joined with press or compression fittings; PP-R/AL/PP-R is joined by socket heat fusion after the aluminium layer is stripped. Choose fittings that are designed for the pipe’s outside diameter and wall thickness.
Overlap- or butt-welded?
Both constructions are used worldwide. Butt-welded pipe (models ending in -B) has an even aluminium wall without an overlap seam, which some markets and installers prefer for press systems.
