Elegant HVAC Duct Design: the Rooms are Ducts, Too

Ductwork is more than just supplies and returns- the entire home enclosure is actually part of the ductwork. Here’s a quick demonstration of how to use room arrangements to direct airflow. From Season 2 episode 9 of 'Home Diagnosis' on PBS.

Watch all the episodes for free right now: https://HomeDiagnosis.tv

Become a member and help make this show! https://Patreon.com/HomeDiagnosisTV

Performance Duct Design & Installation: Advanced DIY

In our LONGEST VIDEO YET, get a comprehensive tour of the concepts, design, tools, and install tips that go into building a home's breathing apparatus- the central duct system. Here I get into both the conditioning duct system (heat pump/dehumidifier/filtration loop) and the ERV fresh air ventilation duct system.

Thanks to Neil Comparetto (https://www.facebook.com/comparettocomfortsolutions/) John Semmelhack (http://think-little.com) and Bryan Orr (https://hvacrschool.com) and many other HVAC pro friends for their continual advice and expertise.

I got all my Malco tools used here at: https://TruTechTools.com

Check out my awesome ride, the Aerocreeper: http://aerocreeper.com/

Check out all of Stellar Engraving's duct grilles: https://stellarairdecorativeventcovers.com/

Learn more about the HVAC design process: https://youtu.be/aCIrbSFWD20

Get consulting or training with Corbett: https://BuildingPerformanceWorkshop.com

Newest DET Verifier Certified in Georgia!

Never taught a DET Verifier training for one before- this should be interesting!

In a customized 1-on-1 COVID-adapted class, Corbett Lunsford trained, examined and certified Treondras Manning, HVAC technician and Georgia’s newest certified Duct and Envelope Testing (DET) Verifier. As a DET Verifier, Treondras is certified to perform blower door tests and duct tightness testing on new construction and renovations in the state of Georgia. He is also one of Corbett’s Mastermind students, and is helping homeowners in the Atlanta area tune the air quality, comfort, durability and energy efficiency of their homes with his building science and diagnostics expertise.

DET Verifier Trainees are taught the accepted blower door and duct leakage test protocols from the book ‘Home Performance Diagnostics: the Guide to Advanced Testing’ written by trainer Corbett Lunsford

Treondras Manning, right before he received his well-deserved certification as a Georgia certified DET Verifier

Watch DET Verifier Treondras Manning test Corbett’s heat pump cabinet for duct leakage in the high performance house his family is building.

Testing a Radon Mitigation System

Corbett teams up with Fantech's aerospace engineer and radon system expert Hamid Massali to prove the radon mitigation field works, and find out how much airflow the radon fan will need to exhaust to maintain safe air quality indoors.

More on this PFEDK system at: https://shop.fantech.net/en-US/pfedk--rn--diagnostic--tool--kit/p401891

More on radon's health impacts at: https://www.cancer.gov/about-cancer/causes-prevention/risk/substances/radon/radon-fact-sheet

Corbett and Grace are not joking around- they will diagnose the crap out of the forever home they're building. Here's another example of creative testing that can tell us secrets about predicting and preventing failures in the indoor physics, chemistry, and microbiology of homes. Check out the Cirrus smoke tool, and others demo'd here: https://www.trutechtools.com/Cirrus-CWI200-Wind-Indicator

More on this house and the TV show at: https://HomeDiagnosis.tv/atlanta-homestead

Heroes of HOMEChem: Atila Novoselac, Building Scientist

Meet Dr. Atila Novoselac, the Mechanic of HOMEChem. More at: https://HomeDiagnosis.tv/homechem

6-Week Mastermind Course Q&A

Teaser for Home Diagnosis Season 1 (eps 3-6)

See bits of four episodes from Home Diagnosis Season 1! More at: https://HomeDiagnosis.tv

Review: EasyHood HVAC Diagnostic Tool $400

Corbett likes tools that are sexy and scary at the same time. This flow hood is both. Measure CFM, Drybulb, Wetbulb, Dewpoint, Velocity, and more with this very affordable tool that will help revolutionize the HVAC industry.

Testing Custom HVAC Grilles with a Blower Door

Watch home performance testing guru Corbett Lunsford test the pressure, airflow, and velocity performance of some beautiful custom carved wooden return grilles, using just a blower door kit, a homemade box, and an anemometer. Grilles made by Stellar Engraving by Vencor Inc. (http://vencorinc.com). Test performed out of the back of Corbett's pickup truck in Atlanta GA! Yeehaw!

DEAR CORBETT: HVAC Equipment Airflow Frustration

Dear Corbett,

I was going thru the videos in the training portal. Overall, I like your videos. However, every now and then, a portion of one leaves me less than satisfied with the answer. Usually, my disatisfaction is because you are rushing through and just skimming the details and explainations. I realize that your trying to limit the video's length and accept it.

However, I found one video that had something that you brought up, but didn't explain that frustrated me enough to write. The video is in the training portal, 'Mastermind Series Jan 2015' at 30:01 minutes in. Your talking about system airflows and you bring up NCI. You go to say how they add up supply airflows, return airflows, and compare it to what the airflow should be to get leakage. You say that that is wrong but don't explain. You finish by saying that system airflow needs to be measured at the blower. 

So, the question I have is: Are you objecting to comparing either the supply or return airflows to what the system airflow SHOULD be (i.e. not measured) or something else?

Would you agree with the following? 
(Equipment airflow) - (sum of supply register airflow) = (supply side leakage)
(Equipment airflow) - (sum of return register airflow) = (return side leakage)

Equipment airflow to be measured at or near the blower by one of the several methods. I am calling it equipment airflow and not system airflow just to be clear that it is what the fan actually produces.

Finally, are you doing full manual J's or just block load calculations to get ballpark numbers?

Thanks,
TJ

-_-_-

Dear TJ-

Great question, and I'm happy to clarify what I meant! Thanks for letting me know when my broad strokes don't actually answer your question and leave you frustrated- I always want to give a full picture of what home performance testing actually means.

My issue with measuring the supply airflows and return airflows, and inferring duct leakage from that is:

1. How do you know what airflow the equipment is producing unless you measure the actual airflow at the equipment? You can use a calculation like 400cfm x tons of A/C, but what if it's heating season, 20 degrees outside, and the NEST thermostat won't let you disable the compressor's service disconnect and still run the air handler? Also, what if the installer targeted 350cfm per ton, or 450cfm?
2. Even if you measure the equipment airflow, you won't be measuring the equipment cabinet air leakage, which is almost always there. In fact, the IECC duct leakage test assumes that 25% of all the duct leakage will be in the cabinet in new construction.
3. The only way to measure duct leakage is to perform a duct tightness test, or for a quicker and more localized look, perform a pressure pan test during blower door testing.
4. Measuring airflow is notoriously difficult. What tool and technique are we using? Pitot tube has high user error, passive flow hood (balometer) is not accurate for residential grilles and low flows, and anemometers need to be corrected for net free area of the grilles. Lots to scratch your head about, and it turns out the best way to measure airflow in the 21st century is still a plastic garbage bag.

To answer your final question, if all you need is a ballpark number, a block load is fine, but I always do a full room-by-room load calculation if I'm being paid to do an actual Manual J.

Hope that helps, and keep the questions coming!
Looking Forward,
Corbett

'Home Diagnosis' Finally Puts Home Performance Testing on Mainstream TV

Grace and I have been trying to make a TV show about home performance testing for years- we've tried three times so far!  This is how it works traditionally:

1. You get a network executive to want to see you as a couple onscreen because they think you're quirky or weird or otherwise compelling in a I-can't-look-away kind of way
2. You work with a production company and pay out of your own pocket to shoot a 'sizzle reel' that shows off the personality of the hosts
3. You remind yourself and everyone else that your show is about SCIENCE, not about relationship drama and being quirky or weird
4. They remind you that no one cares about the topic in reality TV
5. You feel frustrated and you throw the whole idea in the garbage because you don't want to play their stupid game

So we've decided to make the show ourselves, without asking anyone's permission. We find that works best for us- whether self-publishing a book (Home Performance Diagnostics) or making a feature film (The Other One), it always seems to work perfectly when we don't have someone breathing down our neck to conform to 'the way things get done around here normally.' Here's the show that will actually make it onto mainstream television: HOME DIAGNOSIS.

In 2014, we pushed hard for a show called PRESCRIPTION HOME PERFORMANCE to get made, but it went exactly nowhere. We went to the national RealScreen Summit, a non-fiction television programming conference (yeah, I know!), met with all kinds of networks to pitch the idea, and finally had Science Channel interested until they finally said, "wait, we don't want to compete with HGTV." And that was that. But you can still see what the show was like here:

And way back in 2009, we worked with our friends and client Sandy Gordon to make OUR GREEN COMPANY, which resulted in all of us being told by the Discovery Green channel that 'green' was a fad. Look at these kids- so young, so fresh, and maybe clueless!

Stay tuned for developments on HOME DIAGNOSIS- at the very least, it'll show on PBS just like This Old House does, and at most, it'll be running 24 hours a day on every channel there is.  Probably it'll be somewhere in between!

If you'd like to participate in the making of this show, please reach out to us about it!