PEX can’t be directly linked to a water heater. 1st lengthen a pipe 18 in. from a water heater and hook up the PEX for the pipe. • The Zurn formulation additives lead to tubing that qualifies for the very best chlorine and UV resistance as described in ASTM F876, https://martinucjpv.fliplife-wiki.com/3825128/the_basic_principles_of_replace_water_pipes_in_house