Return and Supply in Crawlspace

Inspected 7 year old home. Crawlspace had 6 mil plastic on crawlspace floor, floor cavity insulation, exterior wall vents and opening to area under front porch so there was plenty of outside air flow into the crawlspace. Home using a Heat Pump. At end of air handler is a return w/ cheap fiberglass filter in place. In addition, there was a supply vent installed at the front of unit.
I have seen discussion about sealed crawlspaces, but not this type of set up.
Realtor was there when I completed and discussed. Current owner is a contractor and she was going to ask him about it. What would your thoughts be? Is this allowed?

Supply air and return air is taken from the same area as in a closed loop if you take return from one area and discharge to another you will pressure up the supply side.
Residential does not require outside make up air with that being said commercial buildings only requires 10% outside air as a minimum.

It makes no sense to take return air from a open to the exterior crawl space just a waste of energy. I hope I understood your description of the system

Thanks. I guess my concern is thee an issue with this set up?

If I am understanding your post I would say there is a issue and would address it as so

My statement would be like this

The crawl space is not a enclosed conditioned area of the home and return air should not be taken from a non-conditioned area

Thanks Charley

I see this a lot.

Removing the return will make things worse.

Why did they insulate the floor? Not that it matters.

Had one of these with a pond of water in the CS with mold floating on the water. If they want to make it a buffer zone or conditioned space they need to sanitize the CS.

You need to figure what problems are associated with the setup. Not just that it is there.