Cut holes in the top of the return air duct to match the holes in the panning.
How to install a cold air return on second floor.
At that point you could cut in a large central ceiling return in the hallway of the second floor as centrally located as possible.
In a heating climate the return duct goes near the floor to draw off the cold air and heat it up.
You want to run it so it covers up all the holes you cut in the panning.
For 1 the furnace fan running all day with the a c on might solve some milder heat trap problems for your second floor.
Divide the house into two zones one for each floor.
If the supply ducts are in the floor then the return air should be located up high.
So i guess back then cold air return on the 2nd floor wasn t as important.
If the supply ducts are high or in the ceiling then the return air ducts or grills should be low on.
For 1800 sq foot home including finished basement they put a luxaire 80000 btu 92 high efficiency single stage furnace.
You did bring up an interesting point.
Air circulation in homes which are older and or in poorly designed newer ones equipped with a central forced air system might be compromised because they do not have an air return port installed on the second floor.
It doesn t matter how much you run the air conditioning system during the summer that second floor will always stay much hotter than the first.
If you are in the far north or in the southern us the answer is simple.
Install the square return air duct perpendicular to the joists.
This allows the air to get into the return air duct.
Build a return air box above the opening tall enough to accommodate the properly sized flex return air duct going over to your closet r a drop having built the same r a box in the attic over the closet drop.
You might also want to try adding a ceiling fan in critical rooms like a second floor bedroom.
Add a small return vent duct to each room on the second floor.
This pulls the air across your body.
Return air duct is connected together using s slips and drive cleats.
The problem comes when you use both heating and air conditioning.
You do this and i guarantee you that the second floor is going to be much more comfortable year round.
The ducts in this 1800 sq foot home were all installed in the 1970 s.
The return air vent openings need to be on the opposite side of the room so the conditioned air is pulled across the room.
The air flows across the ceiling in the hallway towards a larger cold air return that does extend to the basement furnace.
