In a pumped system the routing is immaterial, as long as there is a means to purge trapped air from any high points.: I am in the process of installing 20ft of Slantfin type 30 baseboard in a spare room. The room is zoned from the rest of the system. Does it matter if I run the return loop above the coils or below the coils? disregard the aesthetics of the pipe showing, will running the return below the coils have any effect on performance. Thanks for any help.