Looking for old duct sealing spray system for renovation job.

[Rhizzlebop]

We are doing a project renovating a school building thats about 80,000 sqft. Tons of 30 yr old ductwork in the building that we want to reuse.

Once Demo took place, the contractors have tried pressure testing all the ductwork and found its leaks BADLY. They are thus far looking at MANY hundred thousands to replace all the ductwork.

I thought surely there would be a product that could seal these ducts from the inside. I was thinking along the lines of some type of hose pulled through with a spray head on the end spraying some kind of product like rhino liner for truck beds. Its thick enough to seal up about 98% of the ductwork and save the incredibly expensive replacement cost.

I've not been able to find anything like this.

Anyone ever heard of a product such as this? Any kind of internal resin sleeve such as they use on old sewer pipes? Anything else?

Thanks

[doubleduece]

How about sealing it externally with duct sealer at all the leaking seams or fittings

[Rhizzlebop]

All of this ductwork is in an existing school, above existing ceilings that were not planned to be all torn out and its all wrapped in insulation and leaks BAD.

They couldn't even get an inch on the pressure test on one section of the building.

To take all the insulation off, seal and rewrap would cost almost the same as just tearing it out and installing new. (Hundreds of thounsands).

This is why we started investigating internal sealing options. We've been surpirsed to have not found anyone using a thick material, using a spray device drug through the duct to coat the insides. I'm picturing something like a Rhinoliner material.

I would suspect a process like that would be pennies on the dollar in cost and make a better system with a slightly higher R value.

[Lash]

AllTo take all the insulation off, seal and rewrap would cost almost the same as just tearing it out and installing new. (Hundreds of thounsands).



Not even close. ;)

The problem with spraying something inside of the duct is that you'll more than likely be doing it blind. You'd have to spray every sqare inch which would use up a ton of material not to mention take up air space inside the duct all while making the existing duct MUCH heavier... not to mention problems with dampers, fire dampers, and sensors and such. I can't see 80,000 sq. ft. being hundreds of thousands of dollars to replace insulation... especially if most of it is above drop in ceiling.
Tearing off the insulation, sealing the duct, and re-insulating I'm betting wouldn't even cost a 1/4 of what an all new duct install would cost.


The only other solution to LIMIT the leaks is to cut access dorrs in the duct and physically crawl through the larger ducts and seal them up. You're sure to have a handfull of safety issues with that process though. Cross your fingers that the hangers hold.

[Dallas Duster]

Have looked into Aeroseal? Or something like that?

[Lash]

Have looked into Aeroseal? Or something like that?

Never heard of it. Look pretty good on their site though.

Bookmarked :cheers:

[zzonko]

We are doing a project renovating a school building thats about 80,000 sqft. Tons of 30 yr old ductwork in the building that we want to reuse.

Once Demo took place, the contractors have tried pressure testing all the ductwork and found its leaks BADLY. They are thus far looking at MANY hundred thousands to replace all the ductwork.

I thought surely there would be a product that could seal these ducts from the inside. I was thinking along the lines of some type of hose pulled through with a spray head on the end spraying some kind of product like rhino liner for truck beds. Its thick enough to seal up about 98% of the ductwork and save the incredibly expensive replacement cost.

I've not been able to find anything like this.

Anyone ever heard of a product such as this? Any kind of internal resin sleeve such as they use on old sewer pipes? Anything else?

Thanks

What does your engineer say? You do have an engineer, right? Just think of the liability in a school. One of the problems with internal aerosol sealant, in an institutional setting is flame spread and smoke development, I would think.

Rehabbing the old duct system would cost a fraction of what new would cost, just as lash stated.

[Rhizzlebop]

The engineer says ....HI!!!

Rhizzlebop= the engineer

[Rhizzlebop]

....and to your point, flame spread is not an issue inside the metal ductwork.
Flame spread applies when you're dealing with other things in a ceiling plenum space.

[zzonko]

....and to your point, flame spread is not an issue inside the metal ductwork.
Flame spread applies when you're dealing with other things in a ceiling plenum space.


WRONG!!

Like I said, hire a licensed expert

[Rhizzlebop]

Like I said, I AM the expert. Jeez, its what we're paid to do every day.

[zzonko]

Like I said, I AM the expert. Jeez, its what we're paid to do every day.

Well if your an expert, then you know that the statement you made in red highlight is wrong. (if you want I will give you a hint on where to find this info: (NF_A, IM_, _MC)

And another note...engineers traditionaly do not fare well here. Something about the difference between those that actually construct this stuff and get it to work, and those that think they can do that.

[ispip]

Rhizzlebop, what kind of duct work is it? spiral, snap-lock, ductmate, fiber duct? cause this will make a differance. Spraying some sort of material inside like said above is a tricky thing (AND YES THAT STUFF WILL HAVE TO BE PLENIUM RATED, you are in the airstream). I really think sealling all the duct work from the outsides with mastic or peal and seal tape is the way to go, mostly because it sounds like you may have some broken connections that need to be found and repaired. Also most duct sections are 5 foot long for snap lock and longer for spiral so they would not have to tear all the insulation off.

Good luck

[Lash]

....and to your point, flame spread is not an issue inside the metal ductwork.
Flame spread applies when you're dealing with other things in a ceiling plenum space.

Well technically it would be an issue, but thats a whole discussion in itself. Either way, the stuff is going to need to be UL listed (181 I assume) and have an approved NFPA rating (90A, 90B, and possibly 255 & 259) because flame spread inside of duct would be an issue. This is why only certain types of materials are approved for internal duct lining.



NFPA 90A-2002
2.3.3 Supplementary Materials for Air Distribution Systems.
“2.3.3.1. Pipe insulation and coverings, duct coverings, duct linings, vapor retarder facings, adhesives, fasteners, tapes, and supplementary materials added to air ducts, plenums, panels, and duct silencers used in duct systems shall have, in the form in which they are used, a maximum flame spread index of 25 without evidence of continued progressive combustion and a maximum smoke developed index of 50
NFPA 90A-2002
2.3.10.2.1 Ceiling Cavity Plenum
2.3.10.2.1.6. Materials exposed to the airflow shall be noncombustible or limited combustible and have a maximum smoke developed index of 50

[ispip]

ahhh the National Fire Protection Association... what do they know... haha

[Rhizzlebop]

I stand corrected about the flame spread and such. I wasn't thinking right yesterday. I've gotta look into this Aeroseal product. Hopefully they are meeting these requirements.

After the posted below reminded me of that product I remembered seeing it displayed at the Carrier plant once a while back but had totally forgotten about it.

[zzonko]

http://www.aeroseal.com/commercial_duct_sealing.html

"The sealant is UL-listed for smoke generation and flame spread"


I would still get a number on duct rehab (better option) as opposed to Aeroseal. Just old school that way.

[Rhizzlebop]

Zonko, the contractor has said that his price to remove duct insulation, seal all ductwork, and reinsulate the ductwork would be basically the same price as to remove all the ductwork and install new sealed ductwork and wrap with insulation.

We are now getting some pricing on the Aeroseal system for this building.

[zzonko]

That rehab and replacement costs the same does not make sense Riz. In 1992, a major manmade flood hit the Chicago loop. It flooded every basement and sublevel. We went into the city block sized Marshall Field building, and rehabbed 3 basement sublevels of ductwork for about 40% of what it would have cost to start over. I remember that number as it was shared with us. We cut access doors into the duct, removed all the soggy insulation and carp, sanitized the duct, sealed according to pressure class and wrapped with insulation. I am just guessing here, but that duct rehab job was probably one for the record books, due to the sheer size of the project and the time frame we completed it in.

[Lash]

Zonko, the contractor has said that his price to remove duct insulation, seal all ductwork, and reinsulate the ductwork would be basically the same price as to remove all the ductwork and install new sealed ductwork and wrap with insulation.

We are now getting some pricing on the Aeroseal system for this building.

Have you gotten bids from other contractors? I think this contractor is trying to give somebody a screwin'.

[Rhizzlebop]

Guys, this is a several million dollar project thats already breen bid and is under construction. You can't change contractors at this point because of this duct issue.
Literally, part of the roof is off, the interior is gutted and equipment is in the yard.
They've asked for his changorder price to replace ductwork and it was a lot. We are investigating the price for this aeroseal.

[Lash]

Ahhh... contractors got ya by the balls....lol. I love it when that happens! :D

Let us know if you decide to go with the aeroseal. I'm interested to see how it turns out. Hopefully it wont turn out to be a waste of time and $.

[Rhizzlebop]

Well, yes and no. Hes prob gonna get a good price, but were not just gonna accept a ridiculous number either. We can negotiate.

[bouncer]

www.thermacote.com

[doubleduece]

So, this job is site unseen to all of use here, what size is the duct work in question? Why cant you cut access doors in the duct every "X" foot to fix it from the inside?

Whatever media you use will have to have enough backbone to fill gaps and not pool, when tring to fill gaps.


And another note...engineers traditionaly do not fare well here. Something about the difference between those that actually construct this stuff and get it to work, and those that think they can do that.
AMEN


And the reason is comments like this.



Like I said, I AM the expert. Jeez, its what we're paid to do every day.

[tedkidd]

So, what ever happened with this school?