Hi all, so I am starting a master bath remodel and I removed the old drop in tub from its surround. Inside the surround I found this air duct coming from the floor and ending into the wall of the surround. No air comes out when I turn on my ac from any zone in the house. Any idea what is going on here and why and what I should do with it? Thanks!
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Are there any dampers in that line, elsewhere in the house?
There are three dampers in the house. This is located on the third floor. Other zones are the main floor and the daylight basement as the lowest level. I've turned all zones on individually and nothing comes out. Also tested other bathroom fans and hood fan. The kitchen and a family room are right below this bathroom.
A little more detective work is needed. where does that pipe go that fees into it?
It may have a damper that shuts it off,
may also be a bath vent, or a return air line
what other HVAC outlets are in the bathroom and nearby spaces (side to side and up and down)
How many zones do you have in the house? are they cooling only, or also heat?
Not sure where it goes. Three zones in the house. This is on the top floor. I tested all the zones plus other fans. Right below is the kitchen and family room. There is one other outlet in that bathroom. All the zones are heating and cooling. Would a return vent end (or start I guess) against the tiled over wall of the surround?
Do you have an exhaust vent in this bath area?
Do you know where all the vent outlets outside the home come from?
The fact that it was tiled over means someone at some time decided they did not need the function, whatever it was.
There is an exhaust fan in the bathroom. I haven't investigated to see where each outside vent originates. If it's not in use should I cut it and cap it or just leave it be?
Whichever way is easier, or makes you feel better.
If it will be in the way of your planned remodel activities, pull it out.
Thanks so much for you help Mike, I really appreciate it!
And for reference, when I sealed up and insulated ductwork in my attic, I found a 6 inch air line dumping into the attic. it had separated from a duct that was installed, but covered in drywall by the builder and never was operational
I was happy with performance, as is, so removed the duct, sealed the main line, and also where the disconnected register penetrated the top plate of an interior non-load bearing wall.
This is a 6" supply duct with a now destroyed (and probably covered) register boot, it looks to be 14x3. Since there was no air coming out and it was presumably covered, you can cut the duct and put a cap on it as close to the main as you can get. I am an HVAC engineer and I have seen thousands of things like this, and I promise you it is a supply outlet. If you are ok with not having it in that room it will not negatively affect the system - it will just try to push a bit more air everywhere else. I don't like outlets in the toilet unless you can damper them down some, because you want as much negative pressure as you can get with the exhaust fan running. Additionally, the exhaust fan draws conditioned air from the hallway into the room. Sounds like this one is disconnected or dampered shut upstream of this room, meaning you won't notice any difference at all, and you can basically ignore it unless it is in the way.
Thanks so much jacue! My house was built in 95, and I didn't think it would have gone through too many changes in that time. This is the original tub that I am removing so is it possible this was placed here during original construction? They might have done some HVAC zone work when the daylight basement was remodeled a few years back, who knows. Anyway, cut and cap or just leave be both sound like good options to me.
Have you tried pushing air back in the reverse and listening for or looking for where the air comes out? If you have a shop vac, use some duct tape to attach the hose to the end of that vent (with the register boot removed). That air's going to go somewhere.
Have you done measurements correctly? Everyone should do proper calculations and construction estimating before starting any DIY or home improvement activities.