Why Mechanical Engineers & Residential Construction Don't Mix Much: Ross Trethewey, TE2 Engineering

Sat down with my buddy, the fantastic engineer and educator Ross Tre-THEW-ey (https://te2engineering.com/meet-the-team/) to make three videos- this being the first. We dive into how commercial mechanical engineers are trained and how they might approach, rightly or wrongly, your upcoming home project-- and how you can tease the right info into their designs.

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Aprilaire Filter Pressure Drop Chart

Here’s the current pressure drop chart for the Aprilaire lineup that I recommend most often. Hope you find it useful.

Sizing Make Up Air Supply Grilles for Low Velocity

In modern air-sealed homes, any big one-way exhaust fans should be at least considered for their potential depressurization of the whole home. In MANY MANY cases, the building code requirement of make up air only for kitchen fans bigger than 400 cfm MAKES NO SENSE and is stupid and dangerous.

If you’re bringing in make up air, you don’t want it shooting through your home at high velocity- in my experience keeping it under 300 feet per minute (3.4 mph) is a good way to slow it down enough. Here’s a simple trick to size your make up air system for a home kitchen exhaust hood:

The toe-kick area under your kitchen cabinet is 4” high. However many 100’s of CFM you’re bringing in, you’ll need the same amount of feet of length for this toe kick grille.

For example:

300 cfm kitchen exhaust, 300 cfm make up air, 3 ft of length (36 in long x 4 in high)

400 cfm kitchen exhaust, 400 cfm make up air, 4 ft of length (48 in long x 4 in high)

500 cfm kitchen exhaust, 500 cfm make up air, 5 ft of length (60 in long x 4 in high)

600 cfm kitchen exhaust, 600 cfm make up air, 6 ft of length (72 in long x 4 in high)

ERV for Bath Exhaust & in Cold Climates: FAIL or WIN from the Ventilation Manufacturers

Hear it from the people who manufacture fresh air systems, not just from me. ERVs are for very airtight homes (under 2ach50) to balance the exhaust air from pollution sources inside. Download our universal ventilation layout concept at: https://buildingperformanceworkshop.com/s/BPW-PerformanceVentilationLayout.pdf

Thanks to:
Nick Agopian, Renewaire (https://Renewaire.com)
Travis Rasch, Broan-Nutone (https://Broan.com)
Bruno Poitras, Fantech (https://Fantech.net)
Ken Nelson, Panasonic (https://Panasonic.com)
Szabi Fekete, Zehnder (https://ZehnderAmerica.com)

1:16 Continuity of Balanced Ventilation
2:23 Sizing Considerations
3:36 International Mechanical Code Minimum for Continuous Ventilation Airflow
5:04 Boost Mode
6:27 ERVs in Cold Climates
10:12 ERV vs. Dehumidifier

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Testing Ventilation in a Hotel Room: Bath Exhaust and Fresh Air via Windows

If you've ever stayed in a hotel, you've probably been victim to some heinous building science mistakes. Here's one I stayed in that was actually amazingly OVERperforming, so we fixed it ;).

Moldy House in a Moldy World (Mycotoxins, Black Mold, Dry Rot, & Inspection)-Ep309 of HOME DIAGNOSIS

Fungi are incredible life forms that we barely understand- neither animal nor plant. Sometimes they want to live and grow alongside us, which can have massive health impacts. Explore the science of mycotoxins, dry rot, 'toxic' black mold, and how to inspect your home and tune your living space to be accepting of molds, but keep them where they belong.

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Featured researchers and experts:
James Scott- Mycologist at http://www.sporometrics.com/
Rob Dunn- Indoor Ecology Researcher at https://robdunnlab.com/
Coby Schal- Entomologist at University of North Carolina, Chapel Hill
Birgitte Anderson- Mycologist at University of Copenhagen
Jason Earle- Mold Expert at https://GotMold.com
Karen Dannemiller- Environmental Engineer at Ohio State University

Also featuring lots of footage courtesy of Creative Commons and the US DOD. The appearance of U.S. Department of Defense (DoD) visual information does not imply or constitute DoD endorsement. Dive deeper at: https://HomeDiagnosis.tv/episode-309-mold

PRESSURE-SENSING Make Up Air for Homes? (AND WHY IT'S COMPLICATED)- Airscape MUA System

People have asked many times whether a whole-home make up air system can simply monitor the house pressure, and equalize it automatically when necessary. This would handle depressurization from bath fans, kitchen exhaust hoods, vented dryers, and fireplaces. While there IS a system available that aims to do this (https://airscapefans.com/collections/other-residential-ventilation/products/residential-makeup-air-unit), it cannot completely eliminate the pressure imbalances smaller than 2 Pascals because of the variance in wind (and stack effect). I have personally seen fireplaces backdraft with as little as 2 Pascals of home depressurization.

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Extreme Home Environments: Heat, Ice, Microclimates, & Space Stations- Ep 308 of HOME DIAGNOSIS

What is an extreme environment, and what can survive there? Well, our homes are technically extreme environments for most insects, and within our homes there are myriad extreme micro-environments where really strange microbial life flourishes. Let's look into the science of exteme heat and cold, what it does to our citizens and our societies, and spend some quality time in Hawaii and the vacuum of space.

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Featured researchers and experts:
Ian Robertson- Disaster Resilience Researcher at University of Hawaii
David Sailor- Extreme Heat Researcher at Arizona State University
Sarah Henderson- Indoor Air Researcher at British Columbia Centers for Disease Control
Lori Peek- Social Scientist
Rob Dunn- Indoor Ecology Researcher
Jonathan Eisen- Microbiologist at University of California- Davis
Birgitte Anderson- Mycologist at University of Copenhagen
Karen Dannemiller- Environmental Engineer at Ohio State University

Also featuring lots of footage courtesy of Creative Commons and the US DOD. The appearance of U.S. Department of Defense (DoD) visual information does not imply or constitute DoD endorsement. Dive deeper at: https://HomeDiagnosis.tv/episode-308-volcano-land

2024 AHR Home Ventilation Showdown: New ERV/HRVs, Filter Science, Pretty HVAC Grilles, & Make Up Air

FOR MORE SCIENTIFIC INFO ON THE WORSTS: Beware of Air Purifiers, Miracle Products, & Quick Fixes- Ep 305 of HOME DIAGNOSIS https://youtu.be/lwb8d-h6_a8

Very excited at all the innovations displayed at AHR EXPO 2024 in Chicago. See devices and systems demonstrated here that cover all 5 of the Factors of home ventilation: circulation, capture/filtration, humidity control, dilution air, and pressure relief. Chapter navigation below.

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1:07 UV lights, ionizers, and other home electronic air cleaners are snake oil until proven otherwise
1:19 HEPA filters, electrostatic charge, and different media types- Rensa
3:11 Even office supply manufacturer Fellowes knows air cleaners don't need to be more than a filter
4:05 Beautiful grilles and registers everywhere (here from Effectiv)
4:40 Combo recessed light and HVAC grille- Comfy-Light
5:16 Supply ventilation controls from Panasonic
6:07 Prof. Sean Chang is getting the hospitality industry smarter about IAQ
7:36 Exhaust robot arms- Movex 7:56 Biggest residential ERV available (~400 cfm) from Renewaire
8:54 Flow-limited ERV system from Aldes
11:10 How does a Constant Airflow Regulator work? with Frank from Effectiv
13:15 Corey Mullins, FL HVAC rockstar, on why nobody is dehumidifying in FLORIDA?!?
15:02 You can't dehumidify 600 cfm of makeup air, sorry
15:23 Current sensing switch types from Functional Devices
16:29 Modulating steam humidifier from Carel
17:41 Turkish customizable ERV that kicks ass so hard- BSK
19:32 Molded intake screens from BWC
20:26 Zehnder America's unique ERV flow regulation and exhaust filtration
22:38 Fire-safe stair pressurization system from US Draft Co.
22:35 ASHRAE bookstore is not rich in residential information, but we hope it will be someday

2024 AHR HVAC Show: Testing, Mini-Splits, and Why Manual J is Pissing Me Off

OK, running thru line alert- it's been demonstrated to me that we're calculating way too much heating needed for certain homes, and I'm digging into that. There's a lot more going on at this year's AHR Expo though- from new mini-split designs that actually filter and won't need as much maintenance, to geothermal system diagnostics, to the tiniest heat pump I've ever seen.

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0:12 Ceiling fan shoutout
0:18 New test instruments from TPI and Kanomax
3:49 Brent Ridley wins bet on electric backup heat being dumb
5:01 AI-enabled zone damper system 75F 7:30 DC powered 1/10 ton mini-split heat pump, Masterflux by Tecumseh
8:46 Bill Spohn agrees electric backup heat is silly even in Pennsylvania
9:35 New mini-split design with MERV 14 filters and less mold potential, Sharp Electronics
11:28 Heat pump water heaters still don't know how much cooling they make
11:58 Kevin Demaster on Mitsubishi outperforming Manual J (WTF) and geothermal
14:19 Geothermal heat pumps and web-based diagnostics at WaterFurnace
16:11 Duct board PSA 16:45 Custom printed flex ducts, Prihoda North America
17:02 Automated drain pan disinfection solution, iFlo
19:44 TrueLoads new HVAC design software, and John Whitehead is a hoot
22:15 Alex Meaney, MeanHVAC, on why Manual J might be bending the math on heat load calcs

Massive Mistakes in Make Up Air for Homes

After having several clients and colleagues majorly underestimate the amount of dampered make up ducts needed to relieve the suction pressure of kitchen fans on an airtight home, I decided we need to talk about this again. Here's the ins and outs of Broan's Make Up Air Damper Calculator (at https://www.broan-nutone.com/en-us/home/specifier-tools), and how weird it turns out if you use SIMPLIFIED inputs instead of DETAILED inputs.

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Science of Sick Building Syndrome & Environmental Sensitivity- Ep 307 of HOME DIAGNOSIS TV Series

Whether it's named MCS, CIRS, MCAS, etc, the phenomenon of people becoming over-sensitized to their environment is a very real and very painful thing. Let's dig into the science we know for sure- and the cleaning, maintenance, and material selections that can help unaffected families stay that way.

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Featured researchers and experts:
Charles Weschler- Atmospheric Chemist at Rutgers University
Anil & Nilima Mittal- Moldy Home Survivors
Jeffrey Siegel- Indoor Air Quality Researcher at University of Toronto
John Downey- Exec. Dir. of Cleaning Industry Research Institute (CIRI)
Chris Wilson- Dallas Homeowner Doing Renovations
Miriam Diamond- Environmental Chemist at University of Toronto
James Scott- Mycologist at University of Toronto and http://www.sporometrics.com/
Corinne Segura- Healthy Materials Specifier at https://www.mychemicalfreehouse.net/
Atila Novoselac- Building Scientist at University of Texas at Austin
Andrew Whelton- Water Safety Researcher at Purdue University
Jason Earle- Mold Expert at https://GotMold.com
Karen Dannemiller- Environmental Engineer at Ohio State University
Marc Webb- Environmental Chemist at University of North Carolina
Barb Turpin- Environmental Chemist at University of North Carolina

Also featuring chemistry visualizations by Kamil Czapiga (https://Cosmodernism.com) and lots of footage courtesy of Creative Commons and the US DOD. The appearance of U.S. Department of Defense (DoD) visual information does not imply or constitute DoD endorsement.

Dive deeper at: https://HomeDiagnosis.tv/episode-307-whats-that-smell