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: 382

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

Videos

  • Add Videos
  • View All

Latest Activity

Jan Green liked Chris Laumer-Giddens's blog post Rock Wool Insulation for Floor of High Performance Tiny House
16 hours ago
Carly Maltais posted a discussion

Comparing the AirCycler g2 and HRV [Infographic]

AirCycler is excited to share that we have recently launched a new version of our…See More
21 hours ago
SolyMoly, Inc posted discussions
22 hours ago
Home Energy Magazine's blog post was featured
yesterday
Brad Cook replied to Jim Tenhundfeld's discussion LED's and motion sensors
"I don't know what it stands for. See RAB.com"
Saturday
Jim Tenhundfeld replied to Jim Tenhundfeld's discussion LED's and motion sensors
"That makes sense since the same thing happened with dimmable CFL's.  I have never heard…"
Saturday
Brad Cook replied to Jim Tenhundfeld's discussion LED's and motion sensors
"My first thought is whether the motion sensor and/or the LED lamp is a cheap one. I had so many…"
Saturday
John Wagner joined allen p tanner's group
Thumbnail

Energy Auditing Equipment for Sale, Trade or to Purchase

Discuss the pros and cons of the equipment you are interested in prior to purchase. Post equipment…See More
Friday

Home Energy Pros

Welcome to Home Energy Pros – the unique digital community by and for those who work in the home energy performance arena.

Home Energy Pros was founded by the developers of Home Energy Saver Pro (supported by the U.S. Department of Energy) and brought to you in partnership with Home Energy magazine.  Home Energy Pros is sponsored by the Better Buildings Residential Network. Please honor our Guidelines

© 2017   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service