The Y strainer can be installed vertically or horizontally, but the filter leg must be pointing downwards to ensure that any filtered material does note interfere with the main flow. You can find more info in our article: tameson.com/pages/y-strainer
@@Tameson Thanks a lot for the reply! I asked because my brother had a heat pump installed, which requires a Y strainer on the return pipe...the geniuses he hired to perform the installation left the filter leg pointing up. After telling my brother that the strainer was incorrectly installed, those geniuses replied that the leg's position doesn't matter, the Y strainer will filter all the same, the only thing that's important is to observe the arrow that indicates the direction of the flow... Top quality installers 😅 I have a spare Y strainer at home, upon closer examination, seems obvious that if the leg is pointing up, the flow will be easily disturbed by buildup of "dirt" in that narrow space, like you said. Aside from this, it also seems obvious that the leg is meant to be pointing down for maintenance reasons, since the "dirt" will naturally fall out by the action of gravity when the filter cap is removed... but if the leg is pointing up, the "dirt" will remain inside the pipe (if it's heavy enough). There are so many incompetent installers out there, asking insanely high prices for subpar work... it's crazy... and it's even crazier that they double down and try to justify their sloppy work when it's pointed out to them.