Comments on: A Sign of a Good Duct Installer

By: Colin

Colin — Tue, 10 May 2016 02:52:34 +0000

In reply to David Eakin. AeroSeal does require air
AeroSeal does require air flow to move the goo to the hole so when flows drop in tight ducts the Airsealing stops also. I would like to know from AeroSeal what the flow limit it but suspect it might not work for getting flows much below 12 CFM / 100 sq ft which is still a pretty leaky duct. Can it get much below 12? Duct sealers can get them below 0.5 CFM per 100 sq ft and we can to encourage this performance since it's the cheapest way to gain performance at almost zero cost. Testing just to pass code means it is still bad; just not atrocious. For 2000 sq ft house, code at 12 cfm/ 100 sq ft is still 240 CFM which is over have a Ton of energy lost to say nothing of pressure imbalances and the iaq and safety problems that causes.

By: Chris Dorsi

Chris Dorsi — Tue, 10 May 2016 02:06:51 +0000

Thanks Alison for showing
Thanks Alison for showing this example of best practices for duct installation and testing. Both consumers and industry would benefit from widespread implementation of this type of workmanship.

Colin Genge referred to the DOE Energy Code Field Study — which showed that the Texas ducts tested are all over the map in terms of tightness, suggesting that there is little testing or enforcement. Learn more about that study here:

https://www.energycodes.gov/compliance/residential-energy-code-field-study

Or check out the summarized graphs from the study on page 7 of this slide deck from the Compliance Project:

http://habitatx.com/wp-content/uploads/2015/12/Compliance-Project-slide-deck.pdf

By: David Butler

David Butler — Tue, 10 May 2016 01:17:10 +0000

In reply to Jeff Franklin. There's no way Aeroseal can
There's no way Aeroseal can compete with conventional air sealing techniques in new construction. In retrofit, sometimes it's the only option, although you gotta at least ask the question whether there's enough savings to be had to justify the considerable cost. The best solution for new construction is to keep those mechanicals inside the thermal boundary, in which case Aeroseal is clearly overkill.

By: Colin

Colin — Mon, 09 May 2016 21:56:47 +0000

I am sure Austin differs from
I am sure Austin differs from the rest of Texas where we see the lowest compliance rates in the country. Our guess is less than 10% of ducts are tested in Texas overall because it appears that most Code Officials don't bother with ensuring testing takes place. The DOE study showed an even distribution of duct leakage rates from about 8 to 20 CFM per 100 square feet of floor area indicating the ducts were assembled in a reasonable fashion but not tested which would have caused a clumping of results at the 12 CFM mark. I am interested to know if anyone has similar or different experiences in Texas.

By: Colin

Colin — Mon, 09 May 2016 21:52:11 +0000

AeroSeal may be the only way
AeroSeal may be the only way to seal ducts where there is no access in existing houses such as joist cavities for example unless you demolish the ceiling. Not applicable in new houses because a license fee is charged per job, set up time is high and mechanicals such as blowers must be sealed off and it only works when there is leakage flow to move the goo to the hole. Ducts can be sealed much tighter in new houses with mastic and cheaper.

By: Allison Bailes

Allison Bailes — Mon, 09 May 2016 20:53:29 +0000

In reply to J Wright. Not a stupid question at all,
Not a stupid question at all, J. I'm not an HVAC contractor, but my guess is that PVC isn't used for ducts because of cost and availability. The latter is because it's not so easy to find 12" or larger PVC.

By: Allison Bailes

Allison Bailes — Mon, 09 May 2016 20:47:35 +0000

In reply to Jeff Franklin. Yes, Aeroseal is a big time
Yes, Aeroseal is a big time saver. It's been around for a while and is a great product. It's not cheap, but I've heard of some HVAC companies that install all their ducts in new construction and then have Aeroseal come in to seal them. They make more money by moving on to the next job than by hanging around to seal the ducts. Of course, you've got to be making enough on each job to pay for it, but I guess they are.

By: Jeremy

Jeremy — Mon, 09 May 2016 20:45:17 +0000

In reply to David Eakin. This Old House had a segment
This Old House had a segment on Aeroseal a few years back as well. With a price tag of a few thousand $ there's certainly a diminishing return. Personally, I did all our basement ducts with mastic for $45. Will do the vents in the wall if/when walls are opened for other reasons.

By: John Proctor

John Proctor — Mon, 09 May 2016 20:38:10 +0000

Jeff and J. The system works
Jeff and J. The system works — been around since the 90’s. It was invented by Mark Modera, then of LBNL.
Two reports on it:
http://www.proctoreng.com/dnld/NationalEnergySavingsPotentialfromAddressingResidentialHVACInstallationProblems.pdf

http://www.proctoreng.com/dnld/Comprehensive_Diagnostic_and_Improvement_Tools.pdf

By: Richard

Richard — Mon, 09 May 2016 20:31:04 +0000

In reply to J Wright. Aeroseal has been around for
Aeroseal has been around for years down south. It may be the only way to seal small leaks when you are faced with inaccessible ductwork. It is very expensive to the point where you could start over or hand seal, properly hang, ensure no large holes that aeroseal won't fill (over 5/8") and then better insulate the house with the money left over.