Air duct sealing??? Worth the $$$

[mgatepi]

Checking in with the brain trust here!
Recently got a quote for duct cleaning and the salesman suggested that we have our ducts sealed. They use an aerosol product and pressurize the ducts to apply.

Anyone ever do this? Does it help with efficiency or comfort? Worth the cash??

[LWJ]

I believe #1 is air gap sealing - getting your home airtight. Air duct sealing IF you have ductwork under the home or in the attic that is not insulated is supposed to be a good thing. I hear abou slapping a mastic on from outside the ductwork. Blowing something in? That might restrict your flow. Check with an ACCA member in your neighborhood. Those are the folks who have training and know this stuff. I am on a local BOD of ACCA.

Larry

[masraum]

I thought the sealing that you're talking about (after a cleaning) was normally marketed at sealing any dust/grime that didn't get cleaned off of the inside of the ducts to the ducts not for sealing the ducts so they don't leak. In that case, I'm doubtful that there's any usefulness.

[mgatepi]

This process is being marketed as a sealer to stop the ducts from leaking and also for the cold air return from pulling in dust and odors. The claim is 20 to 30% of your conditioned air is lost due to small holes.

What is the ACCA?

Thanks!!

[bivenator]

I worked in the air duct cleaning industry for a few months. My integrity prevented my from continuing. I do not believe the cleaning is effective. I don't have any firsthand knowledge of the sealing process but found the cleaning to be a wasted effort. YMMV

[gshase]

My house was built in 1954 and I have inspected my ducts with a white glove test and I only got a light smear or nothing at all. If your ducts are leaking 20-30 % sealing them with a film of spray coating will have little of no effect. 30% is a massive leak and that issue can not be fixed with taking the ducts apart and resealing and applying a mastic over-coating.

[RF5BPilot]

I think blanket statements about 20-30% loss are misleading. No question that your system could be checked and insulated in unheated areas of the house. But if they start with exaggerated claims, I don't think that bodes well.

Note that it's a reasonable volume, but relatively low pressure system. A few small holes probably won't make a noticeable difference if the ducts are clean.

Me thinks the dangers exist more on paper or in extreme cases than in typical settings. That's similar to the blanket claims of getting 20-30hp from a cold air intake. (Taking a rare instance and claiming it to be the norm.)

That said, if you have an older home and they can demonstrate that you really do have an issue with leaks....then it might be worth considering (along with just replacing the ducts). Their sealer probably wouldn't hurt anything, but it's more like wearing a Bandaid in case you get cut someday.

[mgatepi]

My house is a 2 story 100 y/o farm house.....I have no idea when the ducts were installed and they are buried inside walls and floors......I cant help but think I have major loss from decades old ducts.
Thanks for comments, I am on the fence with this.....

[mgatepi]

Interesting video......

Air Duct Sealing - Ask This Old House - Duct Sealing Services Dayton, Ohio - YouTube

[island911]

Originally Posted by mgatepi

........I cant help but think I have major loss from decades old ducts.
.....

That's what they want you to think.

See Biv's post. (among others)

Ducts - you are not going to have major loss problems from decades old ducts that will be solved by a guy selling clean and seal.

[island911]

Originally Posted by mgatepi

Interesting video......

Air Duct Sealing - Ask This Old House - Duct Sealing Services Dayton, Ohio - YouTube

Worst Ask This Old House I've ever seen. -FWIW

I mean, for example, they actually imagined that the return ducts might suck dust up from the basement (and that would be a problem ) Pay no attention to the fact that the return air inlet is on the main FLOOR - and a hardwood floor at that. Instead, they have the owner imagine a situation where magical evil basement dust is pulled up to the ceiling and pulled into the duct (GASP! this must be fixed!)

[javadog]

Measuring air loss isn't something you see in the typical residential or commercial project but it's something I do all th etime in certain more-specialized types of facilities. Even small openings can create a pretty sizeable loss, if you have enough of them, so don't dismiss it. It's a lot harder than you think to build a really tight room, or duct.

To answer the initial question, it would depend on the type of duct work that is installed. Some types leak more then others. You'd have to inspect them, then measure the losses, before making a decision. You'd also be wise to test the integrity of the whole house. Considering the climate, the efficiency of the installed heating and cooling system, etc. all plays a part in whether it's economical to seal the ducts, or if something else would give a better bang for the buck.

The technology is out there, if you want to use it.

JR

[island911]

The technology is out there, if you want to use it.

Exactly. If you want to see where the heat is going get a thermal imagining camera .

If you want a better system you need to know what is wrong (or right) with what you have.
Imagining problems is designed to take your money and leave believing that the problem is fixed.


If you have a duct seam that split open that aerosol sealer will not help.

If you have poorly designed ducts, that aerosol sealer will not help.

But you can image how it might help.

[VincentVega]

I did this a few winters ago. I bought a cheap smoke pen, turned the fan on and started tracing. Mastic and tape, then insulation where the ducts werent. Worst part of the job was crawling around in the attic and crawlspace and that wasnt horrible.

[crustychief]

I recently re did the ducts in my house. there were gaps on some branches that never had duct tape on them and the span of the gaps were two or more inches. Now my registers have an audible tell when the fan is on.

[GWN7]

This video says mastic seal is the best. I asked a tin basher (he installs ducts). He said mastic is old school. He uses the tape. Just make sure the outside is clean before putting it on.

Duct Seal Tips From TXU Energy & Energy Star | Duct Mastic & Foil Tape - YouTube

[john70t]

Originally Posted by island911

If you want to see where the heat is going get a thermal imagining camera .

Or get a $30 infrared thermometer from harbor freight.
Or better yet, spend $1-200 on an energy audit(blower door to check leaking aka air exchange + thermal camera)

There are all kinds of spray foams, some DIY:
-Open cell (flammable and needs fire coating)
-Spraycrete brand(no experience but looked promising)
-Slow-Rise for sealed walls (drill a series of small holes and inject)

Ducts sometimes have adjustable stop flaps in the basement which can be tuned for the most-used spaces, but if they are under sized for the run to a specific space no amount of sealing will change a bad design.

I'm kind of under the impression that a little interior leaking is not necessarily a bad thing.
If it warms the inside of walls and floors, much like radiant heat, it cuts down the hot-cold cycling of the furnace which only heats the air.
The cycling is where the bills and wear pile up, I've been told.

Cleaning ducts should be done once a decade IMO.
Last year I got an old-house rental done, and one of them was completely clogged with a mouse nest.
I had it redone again this year.
I also used traps/steel wool/foam/vent covers to keep the critters out.
Spent 4 hours shop vacuuming every inch of the basement.

[john70t]

Originally Posted by crustychief

I recently re did the ducts in my house. there were gaps on some branches that never had duct tape on them...

I use the aluminum metal tape.
Duct tape is for holding bumpers on.

[ltusler]

And the aluminum tape is for holding your stick on wheel weights on your race wheels.

[Cajundaddy]

Tight ducting is always a good thing but it's a pretty simple process and a big profit center for certain "home improvement" firms. If they will do the job for a few hundred bucks it might be worth it. If they hammer you hard-sell about the health hazards, black mold, allergies and then quote $3k to fix you up with their proprietary system, tell em to shove off.