[hivacer]

it will work as long as its on one of the sides, and not the front or back, generally the front is where the pipes come out, the front and back are very restrictive for airflow, the sides will be fine. I prefer them on the return if possible, because in the event it backs up with water or leaks if its on the return the water will not go directly down to my circuit board and so forth, but the fan powered ones really should go on the supply since they dont have a warm air bypass.