Comments on: The Secret to Moving Air Efficiently through Your Duct System

By: Allison Bailes

Allison Bailes — Fri, 28 Aug 2015 20:10:39 +0000

Thanks, Keith. I amaze myself
Thanks, Keith. I amaze myself, too. In fact, I’m not sure I really do all this. I guess it helps that I outsource all of the research and writing to the Phillipines.

Regarding how down-to-Earth my stuff is, I’m reminded of what Isaac Newton said:

“If I have seen further, it is by standing on the shoulders of giants.”

My version of that would be:

“If I have been more down-to-Earth, it is by being squashed into it by the boots of giants.”

By: Keith Powell

Keith Powell — Fri, 28 Aug 2015 19:51:16 +0000

Allison, you continue to
Allison, you continue to amaze me with your copious blogs and such down to earth informative information. I appreciate your continued support of building science and the HVAC-R industry. Students of the process so often overlook the importance of the building the systems are placed in (load design), much less the "side job" of installing the ductwork. As processes like BIM move into and grow with residential projects we will all benefit. I am still trying to figure out how the architect/designer/builder expects us to move "16" of return air through inadequate space, often at right angles, changes in plain, and spaces not designed to accommodate airflow.

By: Dan Goss

Dan Goss — Thu, 20 Aug 2015 19:50:47 +0000

To get an immediate
To get an immediate comprehension regarding the loss of capacity with oval ducts (including constricting/ ovaling metal & flexible ducts) : take a styrofoam cup and fill it with water to the top. Next, oval the top. It becomes apparent that the cups capacity changes- just like an oval air duct.

By: Dennis Del Toro

Dennis Del Toro — Thu, 20 Aug 2015 17:58:46 +0000

It's interesting to see the
It's interesting to see the results of this experiment. WRIGHTSOFT list the standard round to oval 90 degree boot to have an equivalent length of only 30'. Reading this, that value varies depending on the sizes being used. How can we properly design air system when given different information?

By: Cameron Taylor

Cameron Taylor — Thu, 20 Aug 2015 17:51:03 +0000

Excellent summary of David's
Excellent summary of David's excellent presentation at summer camp. Meeting him was a highlight of my time in Westford this year. I now see clearly why he was wanting to know more about how poor airflow affected the vapor compression refrigeration cycle (hence my sketch of the cycle, the photo of which you tweeted), and while he told me he greatly appreciated my input, the feeling is mutual when I saw his presentation. The study he and his colleagues conducted on pressure drop through duct fittings is eye opening, and will give me good material for when I teach residential duct design this fall semester. Therefore, thank you for continuing to spread the word about why good duct design is so vital to system performance and human comfort, and thanks also to our friend David for sharing his knowledge in this effort.

By: Curt Kinder

Curt Kinder — Thu, 20 Aug 2015 17:50:04 +0000

Nice article.
Nice article. It is a pleasure to be able to access this content outside of the Green Building Advi$or paywall.

By: Ted Kidd

Ted Kidd — Thu, 20 Aug 2015 17:48:08 +0000

Ouch!
Nice work Allison.
Ouch!

Nice work Allison.