2 seperate returns hvac?

[bzinsky]

So my second floor hvac system has ceiling vents and a ceiling return. Because of this in the winter while the heat is running it's like 25 degrees warmer at the ceiling than the floor. Which also means the heater is sucking in very warm air.

I need to turn all my ceiling fans on which is a pain.

I'm adding a closet which just so happens to be right next to the ceiling return vent. I'd like to somehow build another return that pulls air from down low. I'd also like it to be switchable so I can use the ceiling return in the summer and the low return for winter.

Not sure how this is done.

My current return duct work in the attic is insulated flex duct if I had to guess it's 12-14" wide. There's a grate in the ceiling and the filter is located inside the grate.

8ft ceilings if relevant.

Do they make some sort of Y splitter for thick duct?

 

[LXCam]

They make Y's for everything. And you could either use. Mechanical damper or electric one for controlling your return. Just be concious of your actual air flow if you try to blend them in a partial open position. I would suggest you either get a CFM meter or a manometer for attaining a reading before you modify the return. Then adjust accordingly matching that value if you intend on blending the returns.

 

[ctfjr]

I have a similar situation in our living room / entry area zone. The ceiling height is 20'. All the supply registers are in the floor. I have a return trunk boxed out along side the fireplace chimney. There are 2 returns cut into it. One at ~12" off the floor, the other at ~ 12" off the ceiling. There are motorized dampers on each one, both controlled by the the thermostat setting (heat or cool). In the cool mode I take the return air off the floor (let the hottest air stay up there). In the heat mode I take the return from high - why waste the heat up there?).
It's worked out fine for me.

 

[75gmck25]

Having the air return up high should be a plus in cold weather, since you want to get that hot air off the ceiling and back to the furnace. It might help more if you increased the number of returns in your upper floor so that you have one return for each bedroom.

The total air return CFM will be limited by the size of the return duct on the furnace, but pulling that hot air out of the bedrooms should make them more comfortable than just one return in the hallway.

Bruce

 

[sands35]

It may be possible to use a stud bay to move a return to the bottom of a wall. You will need to find a non structural wall, cut out the top plate, put in a register at the bottom of the wall and install sheet metal to hook up the new "duct" hole to the existing plenum. The stud wall and the sheet rock becomes the air duct return.

Of course, with a new construction home, there would be metal straps in the wall to replace the now missing 2x4s that where cut out to make room for airflow. Maybe you can hide the repair plate behind some crown trim.

Google:
"Code Compliant Repair and Protection Guide"

for the strongtie catalog - page 9

 

[sands35]

Having the air return up high should be a plus in cold weather, since you want to get that hot air off the ceiling and back to the furnace. It might help more if you increased the number of returns in your upper floor so that you have one return for each bedroom.

The total air return CFM will be limited by the size of the return duct on the furnace, but pulling that hot air out of the bedrooms should make them more comfortable than just one return in the hallway.

Bruce

IF the supply and return is at the top, then the hot air that goes in the room will just get sucked right out. Better to have one on the top and one on the bottom. Not sure if it really matters, but probably depends on the climate. Hot areas, return on top - **** out hot air in AC weather. Cold areas, return on bottom - **** out cold air in heating weather.