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3398 Washington Road
Atlanta, GA 30344
USA

773.398.5288

Advanced residential construction and home improvement consulting and owner's advocacy in Atlanta, using the latest building performance diagnostic and modeling techniques and tools. Airtightness, insulation, HVAC, ventilation, moisture, and air quality and EMF consulting for homeowners and building professionals alike.

Videos/Podcasts/Articles

Home performance articles and stories from the field with internationally respected building forensics guru Corbett Lunsford at the Building Performance Workshop. Hear new episodes of the Building Performance Podcast, see new videos from the Home Performance YouTube channel, and learn all about how diagnostic testing (more than an 'Energy Audit') can make home improvement and new home construction a proven process!

Filtering by Tag: acca

Manual J or Not? How to Tell If Your HVAC Design is Bogus

Corbett Lunsford

If you ask for the HVAC design calculations for your project, you might get handed literally anything from scratches on a napkin to a 50 page jargon-filled binder. Here’s an example of a calculation that might look legit, but is actually very misleading. Learn more about HVAC Design: https://buildingperformanceworkshop.com/training Get 1-on-1 help in consultation with Corbett: https://buildingperformanceworkshop.com/video-consulting

Manual J Default Air Leakage Inputs vs. Blower Door Test ACH50

Corbett Lunsford

I'm pretty sure the awesome folks who created Manual J (like Hank Rutkowski- hear my interview with him here), and the softwares we use to run the calculations (Elite RHVAC, used here, and Wrightsoft) do not have a lot of personal experience with the test dynamics of home enclosures, and may never have actually used a blower door before. Here's a demonstration of why it's so important to respect the blower door if you're doing HVAC design for residential construction or home improvement.

Learn to perform and analyze Blower Door and Duct Tightness Tests in my 1 Day Training at: https://buildingperformanceworkshop.com/det-verifier

There are two blower door brands, both available at: https://www.trutechtools.com/system-blower-doors-and-duct-testers.html

See a tour of a full Manual J report below:

Manual S Deep Dive: Selecting HVAC Equipment Based on Manual J Load Calcs- Part 2 of 2

Corbett Lunsford

Picking up where we left off in Part 1 (https://youtu.be/LEKEMI05dJE), Alex Meaney shows a design where a 3.5 ton, a 4 ton, and a 5 ton air conditioner all match a Manual J load, and explores the fine points of practical applications of the 3 rules of Manual S: 1. Select equipment that can handle 100% of the humidity load (latent heat) at minimum 2. Select equipment that does not exceed cooling load by too much (15% for single stage equip, 20% for 2-stage, 30% for variable capacity) 3. Select equipment that does not exceed total capacity by too much (but this rule must be broken in some cases)

Check out Alex Meaney's trainings: https://MeanHVAC.com

Watch Matt Risinger's video on the Build Show about my Manual J report tour: https://www.youtube.com/watch?v=CL-_VjlYnD0

Manual J Deep Dive (and Selecting HVAC Equipment with Manual S)- Part 1 of 2

Corbett Lunsford

Alex Meaney is my trainer when I level up on HVAC design calculations, and he came to visit us and share some of his expertise. Alex reveals what the J stands for and why you should never round up the tonnage from your Manual J software, and gives two rules for Manual S: 1. Never use AHRI data 2. Meet the latent load while not going too far over the sensible load (more in part 2) Check out Alex Meaney's trainings: https://MeanHVAC.com Watch Matt Risinger's video on the Build Show about my Manual J report tour: https://www.youtube.com/watch?v=CL-_VjlYnD0 Learn more about the Science of Homes: https://BuildingPerformanceWorkshop.com Watch the first-ever TV series about the Science of Homes: https://HomeDiagnosis.tv

Manual J Load Calculations: What, Why, How, When, and Who?

Corbett Lunsford

Now that Corbett has been doing HVAC load calcs for almost a decade, he's ready to make this very long (and also much too short) video tutorial about the what, why, how, when, and who of heat load calcs for sizing your HVAC equipment.

Dear Corbett: Why Don't Homeowners Want It Done Right?

Corbett Lunsford

Dear Homeowners: please read and absorb what the quality contractors come up against with typical clients. This is part of why high quality construction and home improvements are hard to come by...

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Hi Corbett,
Hate to bother you, but you said if I had aquestion to get in touch with you. Sometimes I feel like just throwing my hands up in the air and giving up; why did I read that article about making the heating system airtightback in 1992 when I started my HVAC business? And why six years ago did I bother learning about the whole house approach? There are times I wish I wasn’t disciplined and motivated to do things right.

If a customer just wants a new energy efficient furnace or A/C and is not concerned with all the other issues with the house, should I just give them what they're asking for and take their money? Knowing how easy it would be to do that, I just can’t lower my standards. Even companies that are doing 'whole home performance' now, I’m following behind them fixing some of their mistakes already.

I get people telling me about the problems they are having inside the house. The question I’m always asking the homeowner is, If I see some safety concerns or other issues would you like me to tell you? On a service call, the first thing I have to get right is the problem with the equipment, than I can let them know what I see with the whole house and heating/cooling system generally.

I’m always getting pushback on this: "my heating system is just 7 years old, everything's fine." And here I am, telling them it was not installed correctly, and that we have to start all over again.  Always running into oversized furnaces and air conditioners with undersized ductwork.

Not sure if I’m explaining things correctly to the homeowner as to what I’m trying to accomplish inside the house for them. It always seems to come down to the price. Maybe I have to do a better job in showing value to the customer?

Right now, looking at one job, the call was for high end air purifying filters. The homeowner told me the house is 4000 sq ft but might include the garage and it’s 8 years old. Their 5 year old son has allergy problems, $650.00 utility bill a month, a lot dust in the house. They have 181,000 Btu output for heating and 10 tons of cooling! Told the homeowner the first thing we should do is test the house and HVAC systems first before installing the filters. It apparently costs "too much" to fix the problems. Help?
Thanks,
Sal C.


Hey Sal-
Great question, and I feel your pain!  Sometimes it can seem like our clients actually prefer to hire mediocre contractors to do cheap home improvements that make things steadily worse in the house.  I promise you, though, that it's not true. Yes, I believe it's 100% about education and showing the value, and judiciously using the powerful marketing tools Fear and Sex Appeal to do so.

Keep at it. I'll keep an eye out for your success stories to come. 

Looking Forward, 

Corbett

PODCAST #53 A/C CAN BE SEXY: Kristof Irwin on the Magic of Variable Refrigerant Capacity

Corbett Lunsford

Today we talk with Kristof "Handsome" Irwin, founder of Positive Energy in Austin Texas, about why your air conditioner is probably an idiot (bless its heart) and HVAC heaven that you might not have heard about.

To download this episode or hear more, subscribe in iTunes or visit BuildingPerformancePodcast.com