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: 284

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

Home Energy Pros

Home Energy Pros was founded by the developers of Home Energy Saver Pro (sponsored by the U.S. Department of Energy,) and brought to you in partnership with Home Energy magazine.

Latest Activity

Kim Tanner posted videos
26 minutes ago
Mary Desilva posted a blog post

Energy Saving Home Remedies

The quest for a cleaner earth is not one man’s job. It’s something all of us have to work for. In…See More
2 hours ago
Positive Energy posted videos
3 hours ago
Profile IconErnesto , Positive Energy, Cristy Kraus and 3 more joined Home Energy Pros
4 hours ago
Hal Skinner replied to Hal Skinner's discussion 'YGRENE' super fund for energy upgrade financing
"Thanks Susan.  It is appreciated."
21 hours ago
Adin Maynard commented on Corbett Lunsford's video
Thumbnail

Beyond Blower Doors: Zonal Pressure Testing

"Great video. Your approach of simplifying the reading as X/50 = percent leaking to outside (with…"
22 hours ago
Chris Dorsi posted an event
Thumbnail

2015 Habitat X Summer National Conference at Big Sky Resort

July 21, 2015 to July 23, 2015
The 2015 Habitat X Summer National Conference will take place at Big Sky Resort, just down the road…See More
yesterday
Royce Gleason posted a status
"The passion to learn and gain more advanced energy efficiency techniques, news, videos and much more from home energy pros across the globe."
yesterday

© 2015   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service