Although Caleffi does not sell PEX tubing, we do sell universal PEX and PEX-AL-PEX fittings that connect the tubing to panel radiators and to Caleffi's 668S1, 663 and 592 Series manifolds. It's important to select the right fitting and to connect it properly for leak-free operation.
For selection, here is what you need to know: the 680 Series universal PEX fitting will fit any good quality PEX tubing that meets the ASTM F876 standard. The 682 Series Universal PEX-AL-PEX fitting will fit any good quality PEX-AL-PEX tubing that meets ASTM F1281. Make sure the standard is printed on the tubing! If not, we don't know the ID or OD of the tubing so all bets are off.
For panel radiators, where the fitting will be visible from the occupied space, the 681 Series Universal PEX fitting has a nice-looking chrome-plated nut. Otherwise it is the same as the 680 Series which has a brass nut.
Cody Mack, Application Engineer for Caleffi, shows you how it's done in the video below. Let us know if you have any questions! The handy PEX fitting wrench Cody refers to is Code Number 387100; add one to your next order!”