[averellen]

Some background.
Today I pulled down some ceiling tiles in the garage to see how much head room I could gain to install a new garage door. I found styrofoam above that.
So being curious on how well the garage is seperated from the rest of the house I started digging. Its not at all, which I need to fix not only for code but for my families safety.
The house originally came with electric heat 40 years ago, and was upgraded to a forced air system before me. And its a four level side split.
Well one of the main trunks runs through the ceiling in the garage to heat and cool the level above it. Furance is located in other split of the house.
Air flow is excellent so far.
But the trunk running through the garage is 8"X8" and takes up a lot of head room.
Could I replace the trunk with a thinner trunk with the same area without unbalancing the system?
8X8=64sq in, I can get 10X6 which is 60sq in.
Or maybe just run 5" supplies to each of the registers that go through the garage. There is 3 supplies and 2 returns.

Thanks for any suggestions.

 

[beenthere]

Would need to be 12x6.

The supplies to those rooms are probably 6" atleast.
5" won't be enough.

 

[averellen]

Would need to be 12x6.

The supplies to those rooms are probably 6" atleast.
5" won't be enough.

I though about that, but it would become 72sq in. Bigger is better?

 

[beenthere]

When you decrease your height. You change the way the air flows in the duct. As far, as, the dead space at the outside corners is greater. So it needs to be bigger to flow as much air, and have the take offs still be able to receive that air.

 

[averellen]

perfect, thanks
Now I just need to find a 8X8 to 12X6. Or make one

 

[beenthere]

Sheet metal shop can make one for you.