Plenum Issues - Fixing Badly Installed, Leaky Ductwork In An Attic

Came across your video today. As a semi-retired HVAC specialist with 20+ years of experience, you are correct in the fact that this is what you typically see for an A/C install... Usually, a result of the cheapest bidder gets the job, ESPECIALLY in new construction... As I see it, those pressure boxes KILL air flow!! They build too much static pressure, and when you are talking HVAC, it's ALL about airflow, airflow, airflow... Another major issue with this is the quality of the installation. The flex duct is great; however, it MUST be sized & installed properly. All the ductwork should be sized according to ACCA Manual D, and all ductwork must be pulled tight and strapped every 24". You want nice big curves, no hard kinks, and ABSOLUTELY NO pressure boxes...

Frustrating for we home owners who do not and should not be expected to know the industry specs and procedures for a HVAC system or any other functions in our home to include electrical, plumbing or even an auto mechanic as another example. Since innovations like the internet and YouTube we do have some way to vet contractor's work, but its a daunting task and I'm never sure I've covered at least the basics. Point being, I really shouldn't have to. It's sad the industry standard by "professionals" is to make as many short cuts as possible putting more money in the contractor's pocket to include the fact so many people are just lazy. It should be shameful, but it isn't. Sad testimony of the level of work ethic in this country. I don't mind paying for a professional, but we should have some confidence we'll get what we pay for.

The funny thing is that this type of installation is common in very expensive homes.

No comment on the duct at the top/back turning a sharp 150 degrees and squashed up against the roof? I think you said that was the supply to the box!

So I can tell that the interior of one of my boxes is wet on it's top panel. There's some sort of electrical control box mounted to the top of it. The electrical box says "XCI ZONING POCJ" on it, and has a wire running into a wall. I believe it's the control running downstairs to the downstairs thermostat. I think the installation of this electrical box through the fiberglass box, ruined all of it's insulating properties leading to moisture collecting in the top panel at the intrusion point of this electrical box. Well anyways the box is probably 4' L, 2'h, 2'deep the the entire top corner near this mounting is FREEZING cold and pooling water on top of the box. Everything seems soaked on the inside, which is why its freezing cold through the mastic. How best should I fix this? Obviously replacing the entire box is an option, but I really don't know how comfortable I am about doing that, and I assume any quote from HVAC companies is going to be way out of my budget. My idea was to create a but of a "chimney" of cardboard around the electrical box to keep it safe, and then using closed cell spray foam all around that cold section of the box. Would adding this layer of insulation be an effective solution? My hypothesis being that this will keep the dew point inside the box from collecting more water, and it will simply dry itself over time. I even contemplated running the heat and house fan through it afterwards to push the humidity out of the ductwork and into the home, where I can collect and dispose of it via opening the windows (50% humidity outside) and running dehumidifiers. My hope is that solution will A) insulate the box from the outside so that new water stops soaking the inside of the box, (B) removes the existing water from the inside of the box.

What about the kinked flex on the top connection?

Wait, so they just taped the insulation surrounding the duct, but not the actual metal duct joints? I heard you can use tape instead of mastic to seal the ductwork.

When I see systems like this is makes me sad, people have lost their pride and what it means to install good work. Cheap, fast and lazy are the new words for most companies. Sadly the days of old school installers are over, now its all about cheap.

You should've gutted it down to the ceiling line and ran new metal trunk line instead of adding mastic on a ductboard system.

Should the old adhesive/glue be removed as best as possible before adding new adhesive/glue?

When are we going to stop putting HVAC in the attic? They are losing the efficiency if they furnace and a/c.

What is the cure time

Are we listening to you or the piano playing in the background?

Nice work sir I for like to join you for the work am a Nigeria I have experience sir

I would have torn all that out and re ran everything with the proper sizes, using Y branches, instead of tying to repair that restrictive distribution box.

That’s one hell of a hack installation. Where’s the metal supply trunk? What a joke. And this guy is worried about the duct seal. He did the same thing. All they did was add the duct seal around the flex collars that were tapped into that mixing box. Tear that sloppy mess out of there and give the home owners a solid install. Probably charged them a pretty penny to correct the problem..wink wink.

Improvement?? Get a trunkline and get rid of flex, that would be Improvement

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That dust is from that nasty attic space.

I cant believe people think those distribution boxes are correct. You see this in Florida all the time.i would not be worried about the seal i would rip all that crap out and run a metal trunk, flex should ony be run 5 to 7 feet not the whole duck system. The truth is all that duck is wrong if you think its ok then you failed sealed or not sealed.