Dose anyone have experience testing high velocity duct systems?

I've been asked to duct test a Zhender HRV with comfoducts (2" homerun ducts).

I designed & installed a hydronic high velocity system a few years ago. It had 25' of 12" return flex duct, and 15-20' of 6+8" sheet metal ducting, 2 + 2-1/2" branch ducting. I sealed everything with mastic.

I installed the duct tester at the return, and the duct pressure at the nearest supply to the air hander, as I would on a low velocity system. I measured a high duct leakage, I was disappointed. I'm wondering if I should have taken my duct pressure at the supply trunk (6-8") rather than the 2 - 2-1/2" ducts, due to pressure drop.

Any thoughts?

Thanks

 

Views: 410

Reply to This

Replies to This Discussion

This duct system should be tight enough that it should not matter where you test it from.  I recommend you test under negative pressure to ensure you get good seals at the registers.  How high was your reading and what flow range were you on?

When measuring super low flow, do a field check of your duct tester (thank you for not calling it a Blaster) by cutting a 1 inch x 3 inch hole in thick card board and tape it to the flange on your duct tester. This hole should come in at around 16 cfm at 25 Pa with the pressure measured across the cardboard.  If it measures more than that, your duct testing system could be leaking or out of whack some how. 

if the duct leakage is relatively low, 200 cfm or less, the pressure in the duct system will be quite uniform and either location will give consistent results.  If the duct leakage is high, over 500 cfm, we recommend that you do two tests.  One with the probe in the supply register closest to the Duct Blaster setup and one with it in the farthest supply register and average the readings.  

RSS

Latest Activity

Alan Lehman posted a discussion

Zehnder Comfopipe vs. rigid pipe

Hello All,I have installed few Zehnder systems and I am not sure if my rep is giving me the info I…See More
26 minutes ago
Profile IconKatelyn Haas Conrad, Sandra James, arthur wilson and 1 more joined Home Energy Pros Forum
6 hours ago
Diane Chojnowski posted a discussion
8 hours ago
Brett Little's 2 events were featured
11 hours ago
Landon added a discussion to the group Energy Auditing Equipment for Sale, Trade or to Purchase
Thumbnail

BRAND NEW: Fantastic Software for Retrotec

I purchased a new blower door system from retrotec and it came with the fantestic software.…See More
yesterday
CEE posted a blog post
yesterday
CEE's blog post was featured
yesterday
Profile IconAnnette Young, Jordan Bowman, Ruben Martinez and 1 more joined Home Energy Pros Forum
yesterday
Brett Little posted events
Saturday
Ben Thompson replied to Stuart Perkin's discussion TrueFlow in the group Energy Auditing Equipment for Sale, Trade or to Purchase
"Hi Stephen. Do you still have a Trueflow that you would sell? Ben Thompson,…"
Friday
Ben Thompson added a discussion to the group Energy Auditing Equipment for Sale, Trade or to Purchase
Thumbnail

Wanted: TrueFlow plate

Seeking an Energy Conservatory TrueFlow plate (grid) in good condition. Ben Thompson.…See More
Friday
Scott Partlo replied to Jerry Needham's discussion Closed cell on roof deck to prevent mold.
"You say that 2" of closed cell foam is applied OVER the roof deck.  Where exactly was the…"
Friday
ayazfudugo1 replied to Tom Smith's discussion Are Energy Efficient Windows worth the investment?
"For both new and existing homes, Energy efficient windows are an important consideration Heat…"
Friday
Profile IconTodd Williams and Haley Keegan joined Diane Chojnowski's group
Thumbnail

Hall of Shame

In this group, members share an array of images from the field, showing the kinds of issues…See More
Friday
Todd Williams liked Diane Chojnowski's group Hall of Shame
Friday
Home Energy Magazine posted a blog post
Thursday
Leona Zoey posted a blog post

Landlords Are Your Friends

While it may be easy to forget given their apparent position of power over you, landlords usually…See More
Thursday
Ruben Martinez liked Diane Chojnowski's video
Thursday
Haley Keegan joined Building Performance Institute's group
Thumbnail

Building Performance Institute (BPI)

BPI is the nation's premier standards development, quality assurance and credentialing organization…See More
Thursday
Donald Hester replied to Jerry Needham's discussion Closed cell on roof deck to prevent mold.
"For the roof shingle issue that is an unfortunate issue with many home inspectors that have been…"
Thursday

Photos

  • Add Photos
  • View All

© 2018   Created by Home Performance Coalition (HPC)   Powered by

Badges  |  Report an Issue  |  Terms of Service