Heat Pump System Air Filter Returns

[Stephen P. Shockley]

This may sound like a rediculous question, but it is for my own curiousity that I need to find out. If a house uses the square Air filters, does it make any difference in efficiency as to the orientation of the filters when being installed, except for the air flow direction on the filter itself? The reason I'm throwing this out there is that I'm wondering if there is a more restrictive flow of air if the filter is oriented with its v-grooves opposite the direction of the louvers on the return cover doors. I know the air flow direction is a no-brainer, just curious about the other.

[David A. Andersen]

Every time the air changes direction, there are pressure changes.
So yes, but NO it does not matter.

It can't make any significant difference.

[Stephen P. Shockley]

Thanks Dave. For some reason I thought I had seen some markings on a filter I used as a replacement at one time that not only marked the air flow but also was marked with top marking. Could be my imagination from the Tryptophan on Thursday...lol

[David A. Andersen]

Air flow, yes.

There is sticky stuff on one side of some filters and there are reinforcements to keep the filter from being sucked in if installed in the right direction.