PEX-AL-PEX tubing is a composite type tubing comprised of 3 layers (PEX, Aluminum and PEX) bonded together. Since aluminum is impermeable to oxygen, it acts as an effective oxygen diffusion barrier and eliminates the need for an additional EVOH layer (as in barrier PEX), making it suitable for hydronic and radiant heating applications, including warm floors, baseboard/radiator systems, snow melt systems and others.
PEX-AL-PEX vs. Oxygen Barrier PEX
Among the notable advantages of PEX-AL-PEX is it's "memory" property which allows this tubing to retain its' shape when bent. In comparison, oxygen barrier PEX tubing will always try to return to its' original coiled shape unless properly secured.
Due to presence of an internal aluminum layer, PEX Aluminum PEX is less pliable (harder to bend) then PEX with oxygen barrier, but is also stronger, has higher pressure ratings and is more resistant to kinking.
While aluminum layer makes the pipe more rigid, it also contributes to lower expansion/contraction of the pipe (0.3" per 100ft at 10°F change vs. 1"-2.5" per 100ft for regular PEX), making it much quieter then oxygen barrier PEX in under-the-subfloor PEX installation.
Seam-welded vs. Overlap-welded
Since aluminum layer is not a seamless pipe, but rather a strip of metal formed into a round pipe, PEX-AL-PEX is categorized into seam-welded and overlap welded. The former refers to welding of the two edges of the strip together (creating a "seam") while later refers to welding a small portion of the strip over the other strip (creating an "overlap"). Overlap method is known to be more structurally stable and reliable and is the method used for manufacturing of Everhot PEX-AL-PEX piping.
Everhot PEX-AL-PEX pipe can be used in both closed and open type heating systems, including radiant heated floors, hot water baseboards, boiler's main lines, fan coils and others.
It is also compliant with lead-free requirements and can be used for hot and cold domestic water applications.
Everhot PEX-AL-PEX pipe may act as a direct replacement for many other brands, including Mr. PEX, Watts (Radiant PEX-AL), Wirsbo (MultiCor) and is compatible with the connection systems from these manufacturers, including PEX Press method and compression type fittings.