David Richardson posted an interesting piece on changing from % based testing based on conditioned floor area versus the duct area

http://ncidavid.blogspot.com/2013/10/should-duct-surface-area-be-us... 

Personally I see quite a few problems with this based on the way things are done now, but I am curious what you all think.

As for some of my concerns - most installers have no clue what the duct area is because we cant even get them to do a Manual J much less a D (sorry I also have no desire to run a tape against them either)

Leaving the air handler out means more sloppy installs of them & manufacturers wouldn't have to concentrate on making them by default tighter

With that he does make some very valid points & I would love to hear your thoughts

Views: 563

Replies to This Discussion

Interesting thought but the issue with that is contractors bumping up manual J's for bigger units - the 99 occupants, leaky house, etc... tricks we have all seen used to get to there favorite 400 or 500 SF per ton. Granted commercial never sees this issue but that is because they require a mechanical engineer in many cases & also have higher loads than residential due to ventilation requirements

I think John has it nailed - 6% total (at final) & 10% for inside conditioned space (especially for "balanced" systems where they have actual returns in each room) with maybe a max based on nominal airflow. Shoot to make it fair for smaller houses  to promote them maybe even go 8% for homes under 1200 SF. As for reporting, I think it should be both the % but also as Ted points out - actual leakage numbers 

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

Tony Rigdon posted a discussion

Placement of 5/8" firewall, over or under foam board insulation?

I'm adding onto my personal residence and since the house is within five feet of the property line,…See More
44 minutes ago
Hal Skinner replied to Hal Skinner's discussion Rooftop A/C units and exposed ductwork in the group The RCC Classroom (Radiant Control Coatings)
"Hi Tom.   As far as media advertising goes for the good RCCs, it really doesnt work well at…"
2 hours ago
Sean Lintow Sr commented on Chris Laumer-Giddens's blog post Mini-Split Heat Pumps are Quirky, Especially their Capacity
"Quick question Chris - the set & forget (for temperature setbacks) is that with any or just…"
4 hours ago
Martin Smith joined Hal Skinner's group
Thumbnail

The RCC Classroom (Radiant Control Coatings)

A group where energy professionals can learn about all the different energy saving aspects of…See More
6 hours ago
Anthony Cox added a discussion to the group Job Board
Thumbnail

PROJECT MANAGER/BUILDING SCIENCE TRAINER Community Housing Partners Christiansburg, VA

We are hiring and below is link to apply for the position we have available at Community Housing…See More
6 hours ago
Anthony Cox joined Diane Chojnowski's group
Thumbnail

Job Board

This group is for posting jobs related to all aspects of the home performance industry including…See More
7 hours ago
Profile IconBrendan Reid, Brian Keech, Bob Reuther and 1 more joined Home Energy Pros
8 hours ago
Hal Skinner added a discussion to the group The RCC Classroom (Radiant Control Coatings)
Thumbnail

Improved acoustics

Some RCCs claim to improve acoustics .  Here are a few examples of ours.…See More
yesterday

© 2014   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service