How to Size Ventilation Make Up Air: 2 Awesome Free Tools for Design Calculations

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How to Size Ventilation Make Up Air: 2 Awesome Free Tools for Design Calculations

Рет қаралды 8,140

Күн бұрын

Not sure if you need makeup air in a home? Here are 2 quick and easy (and free) tools I use on basically every consulting job I do. Watch how I determine exactly the right solutions for any home, using depressurization analysis and solving with passive and active make up air systems.
Take my Ventilation Training and learn all that I know about this complex topic: buildingperformanceworkshop.c...
Redcalc: www.redcalc.com/red-calc-free/
Broan Make Up Air Specifier: www.broan-nutone.com/en-us/ho...
See a passive make up air system here: • Perfect Ventilation Sy...
See an active make up air system here: • How to Design, Install...
Consult or train with me at: BuildingPerformanceWorkshop.com
Watch the first-ever TV series about the Science of Homes: HomeDiagnosis.tv

Пікірлер: 46

@techfan166 2 жыл бұрын

I'm working on the plans to build my new home and the HVAC is great part of the design. It seems that very few to none HVAC professionals know or even care about this. I asked my guy where i needed to make the opening for my my kitchen make-up air. He said "you should be okay. You dont need one" he knows I'm building a well insulated ICF home in Arizona. I don't want to call him back because he doesn't understand it or care. Great video!!

@HomePerformance 2 жыл бұрын

Thanks Techfan- you sound like you have it under control. It IS hard to be an HVAC equipment service and install technician AND have all this math and science in your pocket too. But they should be trying harder in many cases.

@tommcmillan3143 2 жыл бұрын

Very interesting, I like your strong recommendation regarding a kitchen vent hood exhausting outside. Completely makes sense to me, we do that for everything else, ie, wood stoves, hot water tanks, etc. Somehow the the kitchen range got a pass a couple generations ago...

@HomePerformance 2 жыл бұрын

Exactly right Tom- makes no sense

@Buildingscienceacademy 2 жыл бұрын

Great information! Love the web tools too.

@HomePerformance 2 жыл бұрын

Thanks Brantley

@turboflush 2 жыл бұрын

We run small buisness from a room in the house using a laser cutter. It is forced exhaust outside. House is still leaky enough that it is able to pull from other locations. Looking at installing a hrv to help balance this. Especially once the house is sealed more. 1940's house had some large outside door leaks. Just fixed them. Noticed I have to crack anaposing window to keep exhaust flowing out. I run carbon filters on the hvac.

@HomePerformance 2 жыл бұрын

Be very careful

@erickessler6094 5 ай бұрын

Corbett, This "Ventilation Air Quality issue" is SOO important to us (alergy & lung issues) and the retirement home we're trying to design. We, too, worry about various building materials & health. My QUESTION is about Closed Cell Spray Foam I'd like to use for my conditioned Attic space... and MITIGATION of fibers, fumes, & such for air quality ... Do FIRE COATING PAINTS like "DC315" or "FireFree 88" make things better or worse for air quality? The home will certainly have an ERV & Dehumidifier with MERV 13 filters. Cheers, Eric

@chrisluffy25 2 жыл бұрын

Wow, this is the video im looking for so long! I have a 3m x 9m x 3m space, sandwiched in 3 buildings around, concrete on all sides. Almost airtight, just a 1m x 2m door and 1m x 1m window thats need to be closed most of the times. Haha, what a terrible place. Its so hot right now and difficult to breath. Im just using electric fan for intake near the open window, and exhaust at the other end in the bathroom. Can you help me to plan/build healthy and quality ventilation system for my tiny space here in the Philippines? Thanks a lot.

@jl9678 2 жыл бұрын

Great video.

@HomePerformance 2 жыл бұрын

Thank you buddy

@josephmerritt1411 Жыл бұрын

Good information that I will use in trying to design my new home. Please note that I had difficulty with the Broan Specialty Tool. Using Range Hood Make-Up Air Damper Specifier then selecting "Get Started" produces "HTTP Error 503. The service is unavailable." The web server was unavailable on 1/27 at 1:02PM EST. Hopefully, Broan will get that repaired.

@HomePerformance Жыл бұрын

They have been informed, yes, I use it almost daily!

@Troy-Moses Жыл бұрын

This is exactly what I was looking for! In the example you provided here, I still think passive make-up air is within the threshold of a better tradeoff, and here is why: An 8" dia. duct = ~ 50.3 sq-in, so 5 are = *~251.3 sq-in, which translates to an ~18" dia. hole (or a 16" x 16" square).* The math on the (3) 10" holes is close enough. An 18" motorised damper costs just above $300 on McMaster-Carr; add a grille and a filter box, and you're done. Don't get me wrong, there is a point where forced air is more efficient, but I think that to exchange 800 cfm for the area of a 16" square hole is a pretty good tradeoff -- even on luxury homes.

@HomePerformance Жыл бұрын

Interesting point, Troy

@2ndChanceAtLife 2 жыл бұрын

Still wondering how apartments in AZ pass code with stove exhaust leading to the interior of the living space. Also cheap/slow fans in bathrooms. And no vents in laundry area. I'm in the 4th one in the past 5 years.

@HomePerformance 2 жыл бұрын

Yes, code does not aim for healthy, or anything to do with any invisible dynamics as far as I know- sorry to hear!

@lkbasgiohbasg 9 ай бұрын

Do you have suggestions for how to approach finding someone who can do the math and design a balanced system? Is that all pretty much in the wheelhouse of a good HVAC technician? Should I try to do the math and as much research as I can to be able to evaluate whether someone seems to know what they're doing? Your videos are a great resource, thanks

@HomePerformance 9 ай бұрын

Not in the wheelhouse of most HVAC techs, no. Yes, you should learn as much as you can, since no one will care as much as you do. And I’m happy to help you if you need somebody. BuildingPerformanceWorkshop.com

@timdestasiohvac Жыл бұрын

Corbett, could I use the RedCalc tool for depressurization in reverse to determine how much OA I need to bring into a building with a specific CFM50 leakage to achieve a target POSITIVE pressure of around 2 Pa?

@HomePerformance Жыл бұрын

Yes, same physics Tim!

@timdestasiohvac 2 жыл бұрын

I was about to message you and ask what you use for energy audits and you read my mind

@HomePerformance 2 жыл бұрын

This is a tiny piece, Tim- I also use APT Reports, REM/Design, Fluke SmartView, and Elitesoft

@garyd5298 8 ай бұрын

When calculating the SQ footage on a 1 story home do you also add in the finished basement Sq ft ?

@HomePerformance 8 ай бұрын

Yes sir

@ynotn0w 2 жыл бұрын

I believe you said that turning on the exhaust fan would turn on the makeup air fan. Would it not be better to install a static air pressure gauge to continuously monitor for depressurization and turn on the makeup air fan when needed? That would work when anything in the house causes depressurization e.g. another exhaust fan, clothes dryer, etc.

@HomePerformance 2 жыл бұрын

There is no widely available micromanometer gauge that can do this, unless you know something I don’t. Turns out it’s more challenging to manufacture than it sounds.

@purpleblueunicorn Жыл бұрын

Great idea! Could use a product like this one (aabsmart SPM-100 Dual Port Manometer) for relative pressure, one side outside the home and one in. Would need to feature request them to have a continuous usage mode with API access. I use Airthings devices to monitor CO2 and boost my EVR when levels are high, could definitely do the same for relative pressure.

@HomePerformance Жыл бұрын

Sorry, but that AAB gauge is not sensitive enough, it measures in IWC.

@purpleblueunicorn Жыл бұрын

@@HomePerformance It's accurate to 0.004 inWC (1 PA) and has pascal units. I've used a cheap digital 50$ manometer to do measurements and it's as accurate as my Dwyer 0.5 in water. I think it would definitely work in this scenario, although not as good and precise as the one you have. Might also need periodic recalibration. www.itm.com/pdfs/cache/www.itm.com/spm-100/datasheet/spm-100-datasheet.pdf

@HomePerformance Жыл бұрын

Nice

@josea8015 2 жыл бұрын

Question, using the same comparison you used with ERVs and your buddy with the 10 kids regarding humidity in the home… how big of a deal is this really if you only run the fan maybe 30-60 min a day? Guess it depends on how negative your house gets? I’m about to undergo a major reno in northern NJ and will be installing an ERV but it won’t supply 400 CFM to the kitchen. It’s sized for 4 ppl so low 100’s. Maybe I’ll just open a window on my first fl when we cook :-)

@HomePerformance 2 жыл бұрын

ERVs are never the solution to make up air. And yes, ‘it depends’ is the right answer, which is why calcs are so important for planning. You can certainly just open a window all the way, but it’s not filtered, heated, or premixed, and your home will almost certainly not be pressure balanced- if that’s cool, go for it.

@CH-pp5py 6 ай бұрын

Which video of yours has the details on sizing active make up air?

@HomePerformance 6 ай бұрын

It’s actually simple, Fantech makes a 750 cfm unit or a 1200 cfm unit. Take your pick.

@daviddimovski9595 Жыл бұрын

My take away from this is that if I would like to avoid the suggested 9 holes from the calculator I can introduce a fane to bring in the amount of air required. eg extracted air moves at 3200m³/h through a 250mm/10in hole I would then need to have the same type of fan pulling air in (through a filter) and through the same sized hole to balance it?

@HomePerformance Жыл бұрын

Yes

@daviddimovski9595 Жыл бұрын

@@HomePerformance I am going to speak with my vent guy and see if I can come up with a cost effective solution. It is a shame Australia is sooooo far behind with all this stuff as it makes systems like this quite challenging to design and impliment. I am relly trying to avoid a resurculating system..

@HomePerformance Жыл бұрын

PS you should run your own calculation at the sites I use, every home is different.

@pjb8493 Жыл бұрын

What is the reason the duct size maxes out at 10 inch? Wouldn't it be better and easier to use a single, larger duct, like 16 inch, instead of a bunch of smaller 8 or 10 inch holes?

@HomePerformance Жыл бұрын

Because Broan only makes as big as 10. Feel free to upsize from another brand.