Ductwork sizing, calculation and design for efficiency - HVAC Basics + full worked example

[@EngineeringMindset]

⚠️ *Found this video super useful?* Buy Paul a coffee to say thanks: ☕ PayPal: www.paypal.me/TheEngineerinMindset

[@JudgeFredd]

Done ;-)

[@ralphcalamba5367]

comment the photo of the Duct Pressure Loss Chart Please :(

[@hemanta3758]

@@JudgeFredd so 33

[@grantramsay9956]

Could you do one about fabric ductwork?

[@aaronpomeroy2579]

Bro I wish I saw this a few years ago when I started as an hvac engineer. You described something that took me months to get the full picture from the lax training at my company.

[@mfsperring]

So much of this was over my head but I was able to follow the overall concept. Given the fact I’m not even close to being called an engineer, you really lived up to your channel name. Excellent job of explaining complex issues, in an understandable way, without making me feel condescended to, thank you.

[@deetailing]

Yes I suffered many a nose bleed during this video

[@Rannilas]

Just enjoyed your video for the first time today on its 4th anniversary. 690,606 views is a testament to how well delivered the material was in your video. As I find myself less and less confident in contractors of late, it is appreciated that you are providing content to empower viewers with knowledge that might have felt out of reach initially. Thanks again and many well wishes for continued success for you and your channel.

[@Oldthesis]

This was a fantastically simple overview of the engineering process needed to accurately specify a ducting system. Here in the States among contractors, the most common method for duct sizing in residential is the "friction loss per 100 ft." method wherein we calculate the total equivalent length for the longest runs (both supply and return) and size everything based on getting the appropriate amount of air to these runs and balancing the rest with dampers. Really wish there was an instructional video on this process (or even the equal friction method) in Imperial units out in KZbin. Thanks for providing such fantastic resources for the industry.

[@Ryan-dj5ku]

Look up the "ACGIH Industrial Ventilation" manual. You can download the 23rd edition for free on google. It has step by step examples.

[@jakeedgington]

Yeah this is pretty cool. Im a sheet metal apprentice, specializing in ductwork for commercial jobs. Interesting to see how the ductwork I make is designed and such. Great video!

[@koolkidsklub7901]

I’m the same here just helped commission a job and was curious how they came up with air flow rates on the drawing and it’s pretty insane how much goes into it just for us to come along and make they’re job more fun 😂

[@kimjitchu3799]

As an engineer, this has help me a lot. Thank you so much for teaching and making useful video like this. Dont stop!

[@victory6904]

I got my Ac system installation almost a year ago, it smells very bad and when I turn it on it smells like dump wet bathroom. In order to get it to stop smelling I have to get the temperature down to 24, but then it's too cold😢 does anyone know if they have done for me a cowboy job, as I have spent a lot of money

[@combatwa4les253]

​@@victory6904 24 degree fahrenheit? Or Celsius. Either way you could have someone come potentially clean it, install uv lights or some sort of duct cleaning system. It sounds like it might be mildew caused by not properly insulated duct so it could be sweating and building up water that's smells gross. Could be improper drainage. Hard to diagnose something on the Internet just get a professional to look at it

[@jasonanderson7343]

Another good thing to mind when sizing ducts is the aspect ratio. Ashrae allows us to size on 1:4 basis while CIBSE mentions to size at 1:3.

[@MetrologyEngineer]

*ASHRAE

[@shreddedskull666]

As someone who has been doin HVAC design for a while, this is very helpful if you’re trying to understand the theory and calculations for the design. But in the real world, no one is going to build ductwork like yours because everyone is cheap and prefers round taps and tee junctions.

[@taylorpikor-zs3ym]

Are you interested in designing HVAC for a house I’m building? We’re planning on installing so I can’t find anyone who will just design it

[@MariusSoflete]

Mulțumim!

[@EngineeringMindset]

Thank you!

[@عبدالصمدابوشحاته]

Hi At 15:42 you calculated the C0 from the table and interbolation, and you forgot to calculate the P loss in the bend direction using the formula (P=C0*density*velocity^2/2) ,you have put it into the table directly . Plz notice that and if i'm Wrong tell us the Right plz.

[@michaelorlain4262]

Hmmm i notice that when u do consistency of units it come out like Kg/m.s2. idk maybe im wrong?

[@general6530]

ايش الصحيح ؟

[@hassanas15]

Just want to say, this video fixed my exam project for HVAC

[@salmankhanmohmand9174]

what is your project?

[@Flaix90]

In calculating the pressure loss in the Tee Fitting, why do you only apply the dynamic loss formula in the straight direction and not in the bend too? For the bend you've only used the co-efficient of 0.3645 (15:45) and not used this in the dynamic loss equation, like you did after getting the co-efficient of 0.143 in the straight section (14:45).

[@general6530]

was that a mistake ? or its how it done ?

[@bibekdarjee2833]

I noticed that as well. It looks like an honest mistake.

[@kuangalenga154]

You mention about heating and cooling load calculation on 1:15..have you already done the seperate video?

[@mydrouno]

Great video! Very similar to how I learned in Applied Fluid Mechanics class!

[@syedumerahmed9514]

Wow that’s like our HVAC course lectures❤

[@traninhtoan7203]

Great video !Thank you so much , greatting from Việt Nam!

[@daniel1c]

Great video, it's important to also note that's another driving factor for the mass flow rate is the fresh Air supply which is higher than your cooling or heating loads would override your video size

[@Heatherder]

Agreed. This is where hydronics are strong - separating the ventilation needs from the load needs.

[@rmpalaniappan113]

Great video, For the Tee 'H'at 15:45, is it not the bend coeff' 0.3645 taken from table using vel and area ratios, then using formula to find out the pr loss ?, It says straight from table, the coef 0.3645 as pr loss in Pa. Pls clarify. Thanks.

[@mikea7174]

Amazing video, thank you. I noticed in the video (14.39) you are inputting the data into the interpellation website. that you input in Q11 value 0.14. Should it had been 0.15? (LOL) Its just me and no big deal. It kept me on my toes...so very helpful on your part. Love the videos.....THANK YOU

[@EngineeringMindset]

watch How *AIR HANDLING UNITS* work here: kzbin.info/www/bejne/gXTMp2t_drqenpo

[@hwpraneethb]

Great video this, can you also do a video on "calculating the cooling and heating loads using psychrometric charts" for HVAC systems? Really appreciate it if you can

[@beardedpinoy8645]

refer to ashrae brother, so much easy to follow when you have ashre guidelines

[@michaelorlain4262]

So much help in my project rn. Thanks bro.

[@teoscott1]

Error At minute 15:45 - for the H Tee branch G-I only the value of the loss coefficient was tabulated as 0.36 instead it should have been the value obtained when calculating the fitting loss as was done for the straight duct GJ which gave 0.93 Pa. some clarification needed here?

[@angelamarodelgado7016]

At point H, direction G-I, the correct value is 2.68, and not 0.36, so we would have to correct the subsequent calculations.

[@alekul2020]

Just another very good simple method. Thank you

[@mohdadnan1888]

great video man as always and congrats for 100k subs.

[@liangchayking]

great video, how about exhaust ventilation systems which is the opposite?

[@rajkumarnirlesh7496]

Very informative. I want to try doing HVAC at my home by myself. Thanks for the video.

[@connornewman1992]

1:37 both cooling and heating are positive loads? Or cooling load is (+) and heating load is (-)?

[@Heatherder]

You're paying for them either way. Cooling load is usually electricity, but because of the COP of the unit the actual amount of electricity used may be many times less than that calculated load, but you also have to consider the fans and the water used if it uses evaporative cooling or humidifiers. The heat load is usually natural gas here in Burgerland so you might end up using 5% or so more natural gas worth of heat than the load calculated due to the slightly inefficient nature of burning fuel (you can't breath the exhaust so the heat has to be transferred into usable inside air or another working fluid such as water in a hydronics system). Condensing heaters have come a long way at getting us up to 96% or more efficiency. In any case this is usually still cheaper because natural gas is many times cheaper than electricity is on a raw heating value BTU/hr (kWh) basis.

[@mattllamas571]

Very informatory. I liked this a lot.

[@hridaymaheshwari4209]

Helped me in my project. Great work!!

[@zemhrethagos2575]

THANK YOU AND KEEP THE GOOD WORK.

[@moviesadda9521]

Sohrab: Ques 4:- Coefficient of pressure values of fittings like Reducer=0.25 Elbow=0.27 It will varies or fixed according to CFM Ques 1:- During calculating static pressure only critical path will be taken or not ? Ques 3:- In formula (F×L)/100 F= friction factor or friction head loss Ques 2:- we will calculate all the VCD OR only critical path?

[@user-tr9to2bh6x]

Thank you for good detail’s of informations going keeping

[@ddeonf8296]

Mantaps Good! Love This channel!

[@l.crossjr]

Any plans of making a tutorial on how to read complex ductwork drawings?

[@engineeringmaniac9696]

Excellent One. Thank you for your effort.

[@soksan8770]

Wonder how can we find velocity of air in duct to use for finding diameter of duct in chart ?

[@tuxling3678]

duct supplier has this table.

[@asadahmadkhan1054]

Love from India ❤

[@pepecebolla69]

That was great, thank you!

[@gagekirkwood4224]

Great video, I just have one question. When determining the mass flow rate, in the image it says to use delta T in terms of Kelvin but I believe you used your 8 degrees Celsius to get the mass flow rate for each room? Should we convert that into Kelvin?

[@ahmadqadir94]

Thank you, for giving great and more easily understandable video

[@tanmaysharma5461]

Helpful and to the point explanation , thumbs up!

[@danielofoegbu5532]

0:47 1:15 1:46 2:55 6:13 8:52 9:55 10:30 12:44 12:55 13:32 14:17 15:06 15:55 16:43

[@robferdinand3158]

New subscriber here, great video

[@ben3mar]

Nice and clear video, well done. Do you have any videos on how to calculate proper condenser and evaporater size/capacity in relation to compressor size/capacity on custom AC units ? If not please consider making one. Thanks

[@pattenbarham2878]

Can you do a video on the Velocity Reduction Method?

[@rolandovillamiro1105]

thank you for this video!!! it's very helpful!

[@waheedbashirkhokharkhokhar4485]

very nice sir, HVAC&R ENGINEER from pakistan

[@EngineeringMindset]

Glad you enjoyed it

[@psmeyanburabighchapter3889]

great video..really helpful.thanks engineeringmindset.

[@badrybebo]

Can you please upload full hvac system

[@niceguy4801]

Thankyou so much for this sir

[@mechanicalengineer453]

@ 2:14 delta_T = 8 [Centigrade] but formula calls for [Kelvins], Is there a mistake in the Calculations ? delta_T should be 8+273.15 Kelvins not 8 Kelvins. Thanks

[@peterselie1779]

Delta_T should be 8. It a temperature *difference* between supply and return temps. Let say the supply temperature is 17 C and the return is 25 C. That's 290 K and 298 K respectively. Difference still is 8.

[@tonymarsh9282]

Hi Paul. What a brilliant video thank you very much!!! Can you put a link to the Duct Pressure Loss Chart you used please?

[@EngineeringMindset]

Link is in description, it's for the cibse book. I don't have the copyright for the chart so I can't share the chart unfortunately.

[@igor.castro]

Great video!! Thanks for sharing!! One question: What about split systems? How can I size the ductwork? is it necessary?

[@YasinYTK07]

Intro sounds chiller 😍

[@zakaryakabbara1160]

Thanks for the video, very helpful! I have a question, while calculating the pressure drop in tees (14:45) the pressure loss formula was used with the outlet velocity. However, in ASHRAE fundamentals book 2001, they state that for junctions, the pressure drop is referenced to the dynamic pressure drop for the common section (i.e., main section upstream). Therefore, for junctions, as far as I understand, the inlet velocity has to be used to calculate the pressure drop from the junction either the branched part or the straight part.. could you please enlighten me on this?

[@kimjitchu3799]

what's the answer to this question?

[@moviesjean23]

i actually use simscale what a peace of software

[@ceo-hry02]

Thanks for the video. Which software is best for industrial ventilation duct designing ? Most of the ducting part is round.

[@boedillard8807]

Loved the video - can you make one with Imperial measurements for your slower US brethren? :) You can say - oh just use feet vs... However if the video was done all the way through with measurements we'd likely use, it would be easier to follow.

[@potentialhvac6074]

Nice video! Grill style and size also effect static pressure but that's probably part of a different video

[@chang1006]

Can anyone explain why the Bend Loss Coefficient is used directly as the Dynamic Pressure Loss (15:40) rather than doing the Equation again as shown in 14:53 ?

[@NaworteySolomon-b8j]

pls can you do the cooling and heating load calculation

[@shahramrad994]

Hi, nice video. please note that there is a little mistake in calculation. 1.026 * 8 = 8.208 kj/kg but it is calculated 8.028 kj/kg.

[@teoscott1]

Awesome explanation. Really useful!! Do you have more videos on ventilation duck sizing as mentioned in this videos?

[@EngineeringMindset]

Yes have a look at out channel kzbin.info/door/k0fGHsCEzGig-rSzkfCjMwvideos

[@tnt_castillejos5892]

Thanks for this video

[@lucasserra7654]

Was the cooling load provided in the beginning of the video considered sensible load? Because "m=Q*cp*dt" refers Q to sensible load

[@dpajc056]

@Mech Tuber not that great, you'll be able to have a decent life but nothing great. considering the effort you put into your studies, money spent, and the hours you'll be working, I'd say drop out and do something like medicine if you won't faint at sight of blood, or be a dentist/eye doctor. Much more lucrative.

[@byronjones3579]

Amazing videos seriously.

[@alexeirussoreo7005]

Thank you so much for making this video. Very helpful.

[@jungapo2]

can you also do a comparison of using one centralized hvac system versus mini-split units for the same size of a house having four bedroom and two floors. tks.

[@IceyJunior]

Can you do another difficult example with grille/coil etc.?

[@keithhogan5770]

Great video.

[@etfc944]

Great video this can you make video on DX UNIT

[@brianpimental2948]

Do you do system designs for residential

[@kwongchoming4977]

great video which helps me a lot.

[@0mfgitzramzi]

You’re amazing fam.

[@jakovbilic4556]

Really good

[@md.arrahmandip7638]

Hello there, can you kindly make the simulation process video and upload?

[@jorgebeatorodriguez223]

Great video!!!

[@Mokarika]

how did you get velocity 5 m/s on the duct A, you didnt show it in the video, can somebody please axplaine?

[@krantikumar7929]

Can you plz make a video of flat oval or elliptical duct sizing ,it is helpful for us

[@abdelkaderahmed496]

Hey bro, got any idea of how to find the area of rectangular one?

[@todaslasweasposibles]

god damn i love your content, thanks a lot

[@saddamjaber4551]

I have two comments : First: pressure loss for Tee G-I (bend) is less than G-J (straight) How ? Second: we need link for the duct pressure loss chart thank you so much Great video about Duct Design

[@wemusthavechannelstocommen619]

Out of curiosity, do you only need to bring fresh, conditioned air into the rooms? Is it not necessary to also suck out the stale air using a separate duct system?

[@ralphemerson4533]

This is a great educational video, but I have been doing HVAC design for commercial building for few years and usually you just use 0.1 in wc (water column) of static loss to size supply air ducts. For return air ducts, it’s 0.08 in wc. If you do all this detailed analysis, you will never be able to complete large projects on time or schedule and your firm will loose clients.

[@VivekananthKesavan]

I have a question. While you design hvac systems for your clients how much of the hand calculations do you have to do. or do you just work with the revit software?.

[@h8ryj]

Fantastic and excellently explained. Does anybody know of any online calculation software or any programme that can help with sizing ducted airconditioning units and FCU's with the correct size ductwork?

[@hersonherrera5218]

Thanks! You are awesome. 👍

[@josyptr5341]

The Engineering Mindset :- I have have not under stand Fitting example H : Outlet direction 2-Bend (Time 15:10 - 15:48). Calculated Velocity ratio and Area ratio, then based on that get coefficient 0.364 from bend table. My question is why don't we applied that coefficient value in pressure loss equation {pressure loss=coefficient x density x velocity Sq. / 2}. instead of that directly mention that vale 0.364 as fitting loss in Direction G-I. Anyone please help

[@calvinwijaya2553]

Great video this

[@kaybees7484]

This is so freakin helpful

[@TheMlkhk]

Hi, Amazing video, really has helped me complete an assignment that I had no information on how to complete. However I'm still going to fail because you didn't calculate grilles. Also you stated that you would include the fitting tables you used in the video in the description, but it's not there and I have spend the last two hours looking for a god for saken fitting tables to no avail.

[@EngineeringMindset]

😕? I left 3 links for the exact books you need with all the information in, in the video description. You're welcome.

[@TheMlkhk]

@@EngineeringMindset Aha! I see, in that case, thank you. Your videos are just so well put together and beautifully explained, you honestly really helped me out. Thank you for replying.

[@rohitsuryawanshi8834]

where is the link for duct pressure loss chart?

[@nealrosales430]

Do you have a video that when you have a rectangular ducting instead of round ducting? Amazing video btw. thanks!

[@arifmohamed8610]

Great video..... Thank you so much

[@leonciogarcia9989]

Air volume in HVAC is by sensible heat, without sensible heat. Duct is only GI gage 22 from sizing.

[@Johnetillo]

I love it, thanks!!

[@krantikumar7929]

Plz make a video of external static pressure calculation explain in detail (straight, elbow, offset,shoe or collar piece ,round to Square or rectangular duct ,all type of fittings like VCD ,FFD ,MVCD,MFD etc...)

[@syedsheheryarumer5186]

Great video. Really well explained!

[@TheManolis1984]

You do all this, provide your quotation and you are too expensive. Then a cowboy contractor comes in (who calls himself an engineer), oversizes the ducts, undersizes the fan, uses wrong grade filters and charges far less. Then you are asked to go and see why the system does not perform, you make a list and the customer prefers not to do anything after all when they see the bill. At the end we are out of pocket for the time spent sizing a proper system, twice, and we end up not getting the job. At the end of the financial year we struggle to pay our subscription to the Engineering Council.

[@EngineeringMindset]

So offer them a different business model. Give them a simple 1 page of what seems wrong and if they want the full answer then they need to pay for a review and offer to deduct this from the final quote if they choose to use you. Estimate the financial and energy savings from the improvement as well as how it will improve their work/living conditions.

[@TheManolis1984]

The Engineering Mindset You said the magic word, energy saving. I had customers prefering to go with normal AC motor fans because they were cheaper to buy than EC motor fans that would pay for themselves in a couple of years and start providing true money saving. Anyway, it is a big discussion this one. Great video by the way, as always.

[@hassenfepher]

this business model idea is what we do in the cloud computing world. an architect gives them a basic idea of the price, and work required based on a basic conversation with them, tehn an engineer gives them the actual plan, and hours breakdown, based on a deep dive discovery. a lot of times, we are on or under cost, but that comes with experience. you have to do the calculations to 'pay your dues' as it were until you reach architect level, where you can spitball an estimate, and be pretty close.

[@mushroomcastle5184]

Manolis Theofilos I do the calculations after I get a deposit.

[@Phil198431]

We usually have a contract drawn up before we begin work. Either fee or hourly based.

[@bluemoublue4166]

Hi help please In case we have an hrv or an erv the duct of return air coming out from wc where shall we connect it? Would we mix it with fresh air?