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

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

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:

How NOT to Pick HVAC Registers and Grilles: Aria Vents Test Data Reviewed

One of my HVAC design clients sent me a question about these vent covers he found online, and it cracked open the whole basket of eggs. Here's a brain dump on how to look up the performance data on products like this. Here's a brand of decorative grilles that perform well- I know because I test them: https://stellarairdecorativeventcovers.com/

Learn WAY more about HVAC on our playlist: https://www.youtube.com/playlist?list=PLsc2-5fAgMq5yJOp-kliEoYVML8dS1G2f

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

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

How Many CFM Does My Home Need? Ventilation Advice from HVAC Researcher Jeff Siegel

Spoiler alert: Corbett's wearing a retainer. Yes. You don't have to comment about it. Video forthcoming, as a matter of fact. Jeff Siegel is a superstar of HVAC research, and you can learn more from him in his original interview with me and at his research site. We're in the University of Toronto's rooftop climate chamber, shooting the bull about how many air cleanings per hour (aka air changes per hour, which is confusing to blower door folk) we should aim for in our living spaces. Learn more about specific ventilation strategies at:

https://Broan-Nutone.com

https://AirCycler.com

https://Renewaire.com

https://HVI.org

Bath Fan and Duct Inspection Tips for Restoration After a House Fire

Our friend Shawn had a fire disaster last year, and though it’s a terrible loss he’s helping us and our audience learn from the experience. Here’s a quick preview of what will be coming in Season 3 of Home Diagnosis. Here we point out two things to watch out for- one good, one bad. Easy to inspect a construction site if you know how things are supposed to work! And Shawn’s awesome fitness hammers can be seen at: https://bamfhammer.com/

Mythbusting a Miracle Cooling Machine: Basically a Sped Up Sweat Box- Arctic Air Pure Chill Review

This 'Arctic Air' Pure Chill machine is trying to sell itself as an air conditioner, but it's actually a cleverly disguised evaporative humidifier, like you'd use in an old house in wintertime. Ridiculous. Here's a bit of testing and science fundamentals to help you avoid re-branding and other marketing tricks in your home. For the testing, I used the temperature/humidity datalogger HOBO MX1101.

How to Test HVAC Room Pressurization (Zonal Pressure Testing for HVAC Commissioning)

Using a TEC DG-8 manometer and a Testo 400 hot wire anemometer, Corbett evaluates the HVAC balancing in the home his family built in Atlanta. Keep your room pressures below 3 Pascals if you can, 5 Pascals will start to give you problems- rooms don't receive enough conditioned air, and/or whistling or doors closing from 'ghosts'.

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How Air Pressure Can Screw Up Your Home: the House of Pressure

Take a tour of the dynamics of home pressure with Jake Nuckolls at the Building Performance Center in Bellingham, WA. This training tool has made the invisible visible for thousands of home performance professionals, and we thought everybody else should get to see it in action too!

Thanks to Jake and the BPC- check them out at: https://buildingperformancecenter.org/

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Watch the first ever TV series about the science of homes: https://HomeDiagnosis.tv

Static Pressure Testing for Home HVAC: What, Why, and How in 2 Minutes

If the ductwork of an HVAC system is not designed, installed, and maintained properly, your home may start to have problems in comfort, humidity control, dust, noise, and equipment failure. Here's the basics you should understand before asking your HVAC installer or service tech to run static pressure testing. From 'Home Diagnosis' episode 209- watch the whole episode: https://homediagnosis.tv/episode-209-opening-the-ice-box-cooling-and-drying

Join our Patreon membership and get behind the scenes with us making the next season of the show! https://Patreon.com/HomeDiagnosisTV

Tools used are Retrotec DM-32 gauge and Minneapolis 300 blower door, available at: https://TruTechTools.com

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

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How the Best HVAC Equipment Gets Made: Fast Tour of Mitsubishi Cooling & Heating Headquarters

I've always wanted to go, and am finally learning some new tips and tricks that Mitsubishi puts into their high performance equipment to be a little more ballsy than other manufacturers. See a slice of the innovations in ducted heat pumps, ductless minisplits, testing at extreme environmental conditions, an 11-acre warehouse, a tech support division staffed by HVAC contractors with working demo units and controls, and more. Thanks also to Ryan Burrell who led the technical discussion (and who helped me select the exact Mitsubishi heat pumps that went into our new home).

Thanks to Matt Hoots (https://youtube.com/c/SawhorseDesignBuild) for putting together this trip to Mitsubishi's HQ in Atlanta GA.

Learn more about any of this stuff at: https://www.mitsubishicomfort.com/