Comments on: Another Duct System No-No: The Unsupported Butt Joint

By: Steve Byers

Steve Byers — Fri, 10 Jun 2011 21:47:06 +0000

I appreciate that EV is
I appreciate that EV is talking about butt joints instead of twittering pictures of other bits like some Congressmen...

By: David Butler

David Butler — Mon, 06 Jun 2011 23:55:50 +0000

Ferd, you might want to ask
Ferd, you might want to ask Pulte to see results of the duct leakage test. You can contact me off-list if you’d like help interpreting the results.

Energy Star does not (currently) require air balancing, and I’m not aware of any production builder who has this done. It’s a big issue, because even conscientious builders like Pulte have no idea if the system is delivering correct amount of air to each room.

You can pay a third-party verifier to test the air balance against the room-by-room load calculation (presumably Pulte can provide this report). I’m sure Pulte would be very interested in the results,especially if you’re paying!

The National Comfort Institute is a good source for locating an air balance technician. Just make sure s/he is certified for air balancing.

http://www.certaincomfort.org

By: Allison Bailes

Allison Bailes — Mon, 06 Jun 2011 23:49:59 +0000

Ferd: Is
Ferd: Is the home you're considering an ENERGY STAR qualified home? I know Pulte does a lot of ENERGY STAR, but I don't know if all of them are.

If so, it's been through a third party verification process by a certified home energy rater who did an inspection of the house before the drywall went in and another when the house was finished. The inspections included looking at the ductwork for problems and testing it for leakage. There's no guarantee that the rater used on the house you're looking at caught everything, but an ENERGY STAR home should have fewer problems than one that hasn't had any third party inspections and testing done.

If the home you're considering was part of a sampling process for ENERGY STAR verification, it may or may not have been inspected or tested. It would be part of a batch of up to 7 homes, one of which gets rated.

If the house hasn't been tested, you could always hire someone to come in and test the duct system(s) for leakage and measure the airflow and static pressure.

By: Ferd

Ferd — Mon, 06 Jun 2011 22:42:11 +0000

We are considering a Pulte
We are considering a Pulte built home in Arizonia and were wondering how it woud be p0ssible to have duct systems varified after tings are closed up Pulte talks highly of quality control

By: Allison Bailes

Allison Bailes — Sat, 04 Jun 2011 02:07:32 +0000

Ed: I'm
Ed: I'm always open to increasing awareness of the EV blog and bringing in new audiences. But we're not gonna promise complete satisfaction if a search on 'squeezing butts' is what brought them here.

Christopher: I've read that zip ties also don't do so well in hot attics.

David: Yeah the friction losses would be way too high, but who measures airflow anyway? It's not just really long runs that get butt joints, though. It seems that installers do this also when they're trying to use up the pieces they have left (or whatever's nearby).

If they got paid by percentage of design airflow that gets delivered, I think that would be great. If they did it by the total cfm's, there'd still be the built-in bias toward oversizing.

By: David Butler

David Butler — Fri, 03 Jun 2011 21:30:00 +0000

Although there's no hard-and
Although there's no hard-and-fast rule, I would be suspicious of any flex run that's long enough to require a joint. Unless the flex is completely stretched out tight, and supported without any sags, friction losses for 40' or 50' of flex will go through the roof.

Wonder what would happen if builders decided to pay mechanical subs according to delivered airflow, based on third-party design and verification?

By: Ed Voytovich

Ed Voytovich — Fri, 03 Jun 2011 14:41:47 +0000

Allison . . . you might want
Allison . . . you might want to rethink your nomenclature in this article before the notion that raters go around squeezing "unsupported butt joints" turns into the top hit on FailBlog.org.

Unless your wording is a clever strategy to get as many hits as a Swedish housekeeper in a French hotel.