Fixing a leaky basement duct chase/soffit run properly
I have a small, less than 1000sqft single story house with finished basement heated with a natural gas furnace.
The supply & return registers are on the floor of the main floor, so the ducts run under the floor joists.
Since the furnace room is in the back of the (rectangular) house, there’s a soffit that travels to the front of the house, which runs perpendicular to the floor joists. This soffit contains both the main trunk supply and trunk return air ductwork that the registers branch off from. The soffit is enclosed with drywall & the ductwork is not visible.
In the furnace room, ductwork is exposed (sheet metal rectangular) & I’ve spent some time sealing those up with mastic & foil tape. I’m under the impression that if the exposed work was this leaky, that the ductwork within the soffit is probably in the same leaky condition. I doubt there is any barrier above the ducts and that the soffit is just connected to the floor joist/perimeter walls’ air space.
1) Am I correct that this current setup is a bad setup? Can anyone explain how a system with these parameters would perform?
2) Is the fact that the supply & return ducts are parallel to each other in this single soffit a problem, even if they weren’t leaky?
3) Is my only option to tear down the drywall, seal the ducts, and put up new drywall? Any alternatives? And anything more I should do if I want to fix this the right (aka green/energy-efficient/properly-working-system) way?
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