Author Topic: Aerosol duct sealing?  (Read 735 times)

thenewguy

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Aerosol duct sealing?
« on: April 30, 2019, 10:36:43 AM »
Anyone have any experience with something this? Ballpark cost estimate?

https://www.youtube.com/watch?v=9Q9A8OfxUdk


My house is not particularly dusty, but even after a new HVAC system downstairs, the humidity levels are staying a bit higher than I'd like - which as I understand is indicative of air infiltration/exfiltration. The HVAC installer's suggestion is to just set the thermostat a couple degrees lower so the system will run more and pull more moisture out of the air... which to me seems like a bandaid. I am continually chasing down potential leaks in the attic (would like to try using a thermal camera this summer when the temps are at their hottest), but wondering how significant a factor the ductwork is in all of this.

The claims are that ductwork can leak 20-30% of the conditioned air (not sure if that's typical across all homes, or if more recent construction would be in better shape). By sealing ducts from the inside out, it gets everything - not just the major leaks/joints that are easily accessible. If that 20-30% figure is realistic, it seems like it could be well worth spending up to a couple thousand on something like this.

Mgmny

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Re: Aerosol duct sealing?
« Reply #1 on: April 30, 2019, 11:07:52 AM »
Anyone have any experience with something this? Ballpark cost estimate?

https://www.youtube.com/watch?v=9Q9A8OfxUdk


My house is not particularly dusty, but even after a new HVAC system downstairs, the humidity levels are staying a bit higher than I'd like - which as I understand is indicative of air infiltration/exfiltration. The HVAC installer's suggestion is to just set the thermostat a couple degrees lower so the system will run more and pull more moisture out of the air... which to me seems like a bandaid. I am continually chasing down potential leaks in the attic (would like to try using a thermal camera this summer when the temps are at their hottest), but wondering how significant a factor the ductwork is in all of this.

The claims are that ductwork can leak 20-30% of the conditioned air (not sure if that's typical across all homes, or if more recent construction would be in better shape). By sealing ducts from the inside out, it gets everything - not just the major leaks/joints that are easily accessible. If that 20-30% figure is realistic, it seems like it could be well worth spending up to a couple thousand on something like this.

A couple thousand seems like a crazy high number to fix even a 30% leak, in my opinion. Couple thoughts though: You are in Texas and I'm in Minnesota. My air conditioner only runs heavily in June-Aug (sometimes May-Sept, if i'm being a wussy-pants). Maybe in Texas you run it March - Nov or yearround, no idea.

Second thought: where does this 20% leak TO? If it just leaks out of exposed ductwork near your furnace or in the walls, that's not a big deal in my opinion. Sure it might reduce efficiency a tiny bit, but if you are cooling your whole house, then what's the big deal? You need the interior of your walls to be cooled as well. If your ducts run in your attic outside of the insulation, and that's where the 20% goes, that would be a different story. All of my ductwork runs in 1 plane along the floor/ceiling of our split level. so any leakage would just go into the flooring of our main level or ceiling of our lower level. Who cares? That needs to get cooled as well.

thenewguy

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Re: Aerosol duct sealing?
« Reply #2 on: April 30, 2019, 11:19:47 AM »
(Almost) all of the ductwork is in unconditioned attic space - so any leakage, whether heating or cooling, is pure waste.

Papa bear

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Re: Aerosol duct sealing?
« Reply #3 on: April 30, 2019, 11:38:44 AM »
Attic duct work should be in a conditioned space in the south. If not, it should be sealed and insulated itself.

So, either condition the attic - insulate the rafters and remove the insulation on the ceiling/rafter ties, or do a better job with the ductwork. 

I havenít done the process in the video. Iíve used duct mastic and ul181 metal tape.   If itís all metal duct work, youíll also need to wrap that with some insulation. 


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Papa bear

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Re: Aerosol duct sealing?
« Reply #4 on: April 30, 2019, 11:40:58 AM »
I also agree with the Minnesota poster for northern climates (like where Iím at). I donít care about leaks. Iím heating or cooling a box. And as long as the box takes the heat or cooling and is properly insulated on the outside walls / ceiling, itís not a big efficiency loss. One room or another could have some slight swings, but if you donít adjust your tstat for that, then you have 0 efficiency loss.


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Lulee

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Re: Aerosol duct sealing?
« Reply #5 on: April 30, 2019, 12:20:35 PM »
Saw something this on Ask This Old House and was impressed.  I didn't re-watch the video but as I recall, the homeowner had done a lot of work sealing up and insulating ducts prior to calling for help.

Before spending ANY money to do the work, can you get someone to do an energy audit and see how much your duct work is ACTUALLY leaking and what other type of work around the house might be of benefit you as much or more than sealing the ducts this way?  The tester, of course, would preferably be from someone not trying to sell you something.  Then you can work your way through the various recommendations until you've got the house the best it can be short of ripping things out to the studs.

thenewguy

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Re: Aerosol duct sealing?
« Reply #6 on: April 30, 2019, 12:33:29 PM »
Attic duct work should be in a conditioned space in the south. If not, it should be sealed and insulated itself.

So, either condition the attic - insulate the rafters and remove the insulation on the ceiling/rafter ties, or do a better job with the ductwork. 

I havenít done the process in the video. Iíve used duct mastic and ul181 metal tape.   If itís all metal duct work, youíll also need to wrap that with some insulation. 


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It is mostly metal ductwork, and all already wrapped with insulation. Truthfully, I don't know that I've even got significant duct leakage now or if I'm just falling for marketing hype. I guess that's what I'm hoping to get cleared up.

If there is significant leakage and I were to DIY it - I think that would entail cutting off the existing insulation wrap, sealing as best I could with mastic/foil tape, and then attempting to re-wrap everything. There are some large sections that are entirely inaccessible without cutting into sheetrock, which makes the aerosol approach more appealing.

I've considered making the attic part of the conditioned space, but I think that would be a bigger job than I'm ready to tackle.

Jon Bon

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Re: Aerosol duct sealing?
« Reply #7 on: April 30, 2019, 03:52:57 PM »
I mean if you are determined to grab the fruit off the very top of the tree and requires a really expensive cherry picker to get the highest fruit possible.......

I love this old house, but they love to find new and fancy (read expensive) ways to do things that might not even had needed done.

lthenderson

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Re: Aerosol duct sealing?
« Reply #8 on: May 01, 2019, 07:36:15 AM »
You've got two problems. Humidity and unsealed ducts in unconditioned spaces. For the latter, you certainly can seal the ducts from the interior using the method you linked to but I'm guessing the payback period will be a long time unless they were horribly installed. Like others said, this is not low hanging fruit. The low hanging fruit is to improve insulation and seal up the exterior house to prevent unconditioned air from leaking in and conditioned air from getting out.

Your other problem is humidity which really had nothing to do with your other problem. If your air conditioner isn't removing enough water to be comfortable in the house, your two options are to set the temperature lower as suggested or to get a dehumidifier. Make sure your exhaust ventilation systems work well above the kitchen stove and in bathrooms so you aren't introducing more moisture inside your house.

zolotiyeruki

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Re: Aerosol duct sealing?
« Reply #9 on: May 01, 2019, 10:58:45 AM »
I'm actually near the end of my own HVAC-leak-chasing escapade.  The original builder of our home had an HVAC installer who was either rushed, lazy, incompetent, cheap, or apathetic, because the duct sealing is haphazard at best.  I've been gradually relocating and resealing lots of our ducts, and there are some massive, gaping holes in a lot of the joints.  The issue isn't so much heat loss/gain; rather, it's the fact that some rooms don't get nearly enough air, at least partially because of the shoddy sealing of our ducts.  So our master bedroom feels great, but the other three bedrooms are hot in the summer and cold in the winter. 

A bucket of mastic goes a long way, and it's actually kind of fun to apply.  It's like thick, goopy paint, and you don't need to be particularly careful with it.
 Another benefit of the process has been that I've found blockages and damaged/collapsed ducts that I've been able to fix as well.

FreedomSeeker

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Re: Aerosol duct sealing?
« Reply #10 on: May 19, 2019, 03:18:00 PM »
I know this is an older thread. I actually had the aero seal done on my home.

A little background:

We have a capecod built in 1927. As some point a forced air system was retrofit onto the house. We have central air and heat.

At the same time as the aero seal we got our attic and second floor dense pack insulated and had all the cracks sealed.

Prior to all the sealing and insulation the upstairs was always much hotter in the summer and colder in the winter. We needed a supplemental space heater in the winter and a window ac unit in the summer to make it tolerable. The downstairs was always perfect.

The aero seal absolutely sealed the ducts. I used a wind speed device I ordered on amazon to measure before and after. The air definitely was stronger after the sealing. However, our duct work was so poorly designed that it didnít alleviate the need for supplemental cooling in the summer on the hottest days. The winter is so warm upstairs that we can turn the furnace during the night but I suspect it was the insulation that does the most good.

In the end I wouldnít have gotten the aero seal knowing what I know now and just got the insulation. Not very expensive and huge impact.


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