Current floor vent location is on right, with a dedicated duct to it from trunk line in basement. The fancier grate is propped into a former vent location, and there’s a capped duct that terminates just in front of it, running under floor from the duct that was in the open space on the opposite wall.
In tearing things out for the bath rehab, I uncovered some rotted 10″ x 3-1/4 duct work under the floor (currently under the OSB above)…that goes to nowhere. A patch in the bathroom floor (where the fancy grate is sitting above) indicates there used to be a boot on it and a floor vent. Now, the heat for this room is served off a separate duct that goes only to this room (see the grate to the right).
The dead-end duct is a 90° off the run that feeds a floor vent in what will be the guest bathroom, and did (and will again) continue up to a single boot/vent on the third floor.
Vent location in “new” bath, off stack that comes up inside wall on first floor.
The run up to the third floor was slapped on the outside of the wall in what will be my shower.
So, having already torn off most of the plaster, I plan to run new (non-rotted) 10″ x 3-1/4″ duct in the wall up to the third floor, which will necessitate building out that currently 1-3/4 deep wall a bit before putting up Wonder Board. I have to build it out anyway to fit the plumbing.
What’s left of the ductwork to the third floor. It will be pushed into the wall, which I’ll then build out 2-1/2″ to fully enclose the ductwork and the plumbing.
I doubt there’s any issue with replacing the straight run and the boot in the “new” bathroom and on the third floor.
But here’s my question: Is it acceptable to replace that (currently dead-end) 90° run to the old bathroom, attach a boot and move the floor vent back to where it clearly was before, thereby having three boots/vents on that one run? (Any issue from an HVAC standpoint, I mean…I do realize the vent location in front of the walk-in shower is not ideal, but it would solve another problem.)
The problem it would solve is to get rid of the ductwork currently serving the old bathroom. That run was slapped on the outside of a wall in my pantry, and when I redo the kitchen (If I don’t give up on this crazy house project before then, that is), I’d dearly love to push into what is currently a full bath on the first floor (off the dining room, which is weird) to make what is now the pantry large enough to be a 1/2 bath (which is to say I can’t just bury the ductwork in that wall, because it would still be in the way of making the room larger).
Quite annoying placement for this ductwork in the pantry below the bath – it stymies my future kitchen rehab planning. (This really was a decent if too-small pantry…until I had to rip out all the shelving to access the plumbing chase. And now that whole wall has to come down to remove the black mold on the backside of the drywall – yuck.)
That full bath on the first floor? It was once a butler’s pantry. And if I can figure out the HVAC problem, it will be again. Someday. Not soon.
Oh – and in case it helps, here’s the view in the basement of both of the runs in question.
The one on the left is the one that runs in the wall up to the second floor – the one I would like to use to serve three vents. The one on the right, which runs through the pantry and serves only the old bath, would go. Note that they are both on the same trunk line.