The attic HVAC duct trunk has a hole in one of the seams approx. 1" wide. I can also feel air leaking from other seams in the trunk. Is this normal acceptable loss? Should I just use foam sealant or is there better methods to close off the leaks? Also, there are few dents in the trunk. I doubt it's worth replacing/fixing but didn't know if this would impact air flow..
The bedroom that's at the end of the trunk is freezing so I used the dampers to close off other rooms to redirect flow. The damper is really tight and doesn't seem to want to move more than a few inches in each direction. Also, some of them are covered in tape that need to be ripped to get access. I don't feel a leak but it is odd to me that they are not exposed.
I recommend you seal all of the leaks and insulate the main trunk.
Butyl foil HVAC tape is good for sealing that hole. I suspect that fabrication work has a lot of leaks, and butyl tape will be good for most of them.
You can use duct sealant for seams.
The main trunk needs foil faced fiberglass duct insulation. Closing leaks and insulating that trunk will make a noticeable difference.
For the leaks at the flexible duct connections, you could first try using cable ties and tighten with a cable tie gun. If that doesn't stop the leak then pull off the flexible ducts and use mastic and cable ties for a good seal.
Also recommend check the area for mold, particularly above and below the uninsulated trunk.
You need to seal the holes. Clean the area so things can stick. I like quality aluminum foil tape for bigger holes. Then for seams I use duct putty which you paint or trowel on and it hardens sealing the holes. Then I would insulate your duct since it's running through a hot/cold attic.
I can vouch for the savings coming your way if you follow the advice given. Be sealing all the plenum leaks and replacing the plenum insulation from R6 to R8, my AC bill was but by 1/3. Your savings might be even better since your plenum is currently uninsulated and yours is used for both heat and A/C.
Your attic looks a lot like mine. The job sucks, but the payoff is worth it. I did it last spring when things warmed up enough to not require heat, but before it was hot enough to require A/C.
Local HVAC guy came over. He said the trunk isn't wrapped because it has insulation on the inside? He noted that there was no moisture on the trunk. I can't see inside but a quick google shows that it's possible? Anyhow, he mentioned I could upgrade from R6 to R8 for the duck piping to the registers but he didn't think it would make a huge difference. He said every seam should have been sealed with HVAC tape including the many small holes (like why? how?). We also didn't notice any major leaks where the piping connects to the trunk.
Fixing the various leaks at the seams should be something I can tackle. For the seams, should I use tape or putty? The HVAC d00d said tape but putty was mentioned here. Tape would be easier.
Foil tape is easy to use and does an excellent job of sealing.
The duct only needs to be reasonably clean as the tape has excellent glue on it.
If you have a sharp edge..... double the tape over it.
You can use mastic foil backed tape for everything. Apply the tape at room temp if you can. Use a knife, vice scissors, to cut it and apply it to the surface with pressure.
Your soapy water plan will work, but I would recommend taping over any area that you are concerned about.
The mastic has strong grip and will last many years.
I mentioned duct sealant earlier, but the tape works well also. I like the liquid sealant to seal round duct seams, but you can do same with the tape.
Thanks for the help. For the small holes, wouldn’t a duck sealant be easier than to constantly cut small pieces of tape? Ton of small screw holes that I could patch up
Small Holes can be filled with putty and seams and big holes can be fixed with tape. It’s odd but just a ton of small holes and gaps here and there. Sloppy.
I'd like to install a toe kick register and doing so will require cutting through a 9-1/4" TJI foot joist. Issue is the TJI is one of three supporting a 6ft wide cantilevered floor (not counting the sides), which extends out from the foundation wall 2 feet. The joists are spaced 24" on center and tie back to a doubled up TJI 36" that runs perpendicular (main floor joists). The cantilever supports a row of cabinets with a slab of quartz so there is a significant amount of load on it. For this reason, I am a little leery of cutting a large hole through one of the joists. I had planned on running a 6" duct, but the duct run from supply trunk to register will only be about 6ft in length so I was thinking I could get away with a 5" or even 4" round duct. Or perhaps use a reducer to pass through the joist then back to 6" on either side. What do you guys recommend?
I've been running an dehumidifier in the winter months. It turns on/off with a Nest Thermostat and is connected also to a Tjernlund Airshare fan. The installation wiring was talked about in [url=https://www.doityourself.com/forum/ducting-air-circulation-ventilation-systems/589599-wiring-tjernlund-airshare.html]this thread[/url] a few years ago.
The fan has stopped working, but I'm not sure how to troubleshoot. Any insight?
01-26-21, 08:55 PM
