On Jan 6, 12:01*pm, mcp6453 wrote:
The return air duct on my upstairs heat pump (the same one with the
thermostat issue also discussed here) sucks air through the filter at
such a high velocity that the filter is not of much value. (It also
pulls the bathroom door up against it, if I'm not careful.) The present
grill is 20x25x1. I cannot find a much larger one. Is there any reason
that I could not or should not add a second 20x25x1 above it? There is
room on the wall, and the AC guy says that the duct work is not that
hard to do.

Air Bear is a good filter that seals well, April Air dont seal to the
case. Isnt ductwork sized for the cfm of the blower, a sizing chart
should not be hard to find to see if it was done right.