If this was HVAC, then yes, but since this is a kitchen vent, I would like to see a picture of the filter, specifications too.

Just to clarify, it would be very unusual to have an HVAC air return in a kitchen, since they should not be installed in a kitchen or bathroom.

I believe this happens to be a Florida reference, but its based on the IRC. Item 4 under prohibited sources. https://up.codes/s/return-air#:~:text=3%20Inlet%20Opening%20Protection,2%20inch%20(12.7%20mm).

Bruce

It’s not a kitchen vent. That is in my cooktop. So this return is hvac only.

I am in Virginia. There is no filter.

An average grille can only pass 50% "free air", so if your duct is properly sized at 168 square inches your grille should be twice that area.

As a rule return vents are near the floor and not the ceiling. Are you sure this vent is not blowing air out into the room?

No, it's not a problem to make the opening the same size as the ductwork. Think about it: making that change is no different from extending the ducting by a few inches.

Many houses have retrofitted A/C in the mid-atlantic area and one common location for the A/C unit is in the attic. They find it much easier to locate an air return in the ceiling, so its relatively common.

Decreasing the size of the grill is not an issue, but pulling return air from your kitchen is still a bad idea. If you are cooking and the HVAC is running, you will be pulling cooking odors and heat from your kitchen through the entire house. The reason you have a kitchen exhaust fan is to move that air outside and not circulate it through the house.

Bruce

I verified that it is not blowing air. It is a return only. For some reason, the builder (Ryland) placed it in the kitchen/breakfast room area. Based on these responses, I will have the drywall fixed and look for a smaller air return grill. Thanks, all!

“As a rule”, whose rule is that? Do you have any contracting experience?