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

How to design a duct system. In this video we'll be learning how to size and design a ductwork for efficiency. Includes a full worked example as well as using CFD simulations to optimise the performance and efficiency. FREE SimScale account (www.simscale.com/)
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[@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?

[@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.

[@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 😂

[@mydrouno]

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

[@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.

[@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?

[@mohdadnan1888]

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

[@liangchayking]

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

[@ahmadqadir94]

Thank you, for giving great and more easily understandable video

[@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

[@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

[@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

[@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

[@alexeirussoreo7005]

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

[@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.

[@NaworteySolomon-b8j]

pls can you do the cooling and heating load calculation

[@tnt_castillejos5892]

Thanks for this video

[@PAVANPAVAN-hl8uo]

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

[@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

[@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.

[@Mokarika]

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

[@EngineeringMindset]

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

[@محمدخالد-ب1ذ9غ]

Good work .

[@reliableengineeringsolutio8890]

Very good

[@glasshalfempty1984]

This is insanity...I mean...for large buildings, this is absolutely essential. But for small offices and small homes, surely you can simply this and still get results that are perfectly sufficient? Any negative effects in such a small and simple installation couldn't possibly be that significant with a more simplified method of ductwork design. Unless the design work was 100% guess work, I just can't imagine there isn't a simpler way to do this on the small scale. Example: I have a one story home with a fully submerged basement. One room has a significantly larger load than the rest of the home (TV, computer, UPS, File server, mini fridge, and two people that are in there frequently)...there must be a relatively simple way of figuring out how to move enough of this room's air to the central unit fast enough, in order to remove the heat at a rate greater than that which it is being built up with fewer calculations.

[@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.

[@l.crossjr]

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

[@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 ؟

[@shahzaadsaifi9953]

you put *fitting loss=0.93Pa* in the table for G-J direction by equating: coeff.(0.143Pa) x density x velocity out^2 ÷ 2 but for G-I diection, you just put value of *coeff.(0.36Pa)* into the table. I didn't understand why didn't you applied fitting loss formula for G-I direction?

[@TecraTube]

I don't know a darn thing about HVAC but I do know maths. Towards the end, you discuss losses and using baffles to compensate. I don't see anything about the origination fan, it's CFM, and any filters throughout this system. I would like to build out my own system originating from a window and a plenum box, where a blower is first, then a MERV or HEPA filter, followed with 4 UVC lamps. This system will only supply two rooms with a "junction" or collector as I call it, in-between both rooms (hallway) that is again supplied with a MERV or HEPA filter and UVC lamps out to the second room. Second room is much larger than the first originating room. Two exhausts, one inside origination window above and other through window of second room.

[@kuangalenga154]

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

[@tiagoferreira6713]

Hi, Another great video. Thank you! I have a question. For an equal pressure drop per meter in all of the ducts you used non-commercial sizes like 0.24 m or 0.39 m (at least in Portugal they don't exist). Actually, you will have to use the commercial existing sizes if this would be a real project, right? In that case, it is really possible to maintain an equal pressure drop per meter in all ducts?? Or actually you will never have this in real life, it is just a theoretical method and you just try to find the sizes that allows you to have the most similar pressure drop per meter as possible (per example, between 0.6 to 0.8 Pa/m)? Sorry if it is a stupid question. Thanks in advance. Best regards

[@EngineeringMindset]

Duct can be made to any custom size but it will cost more, to save money and use standard size only then adjustments need to be made to the calculations and reiterate

[@jeffsond]

Thx!! Question, I have a 440 sq ft hunting cabin. I have an electric furnace and a 1.5 ton condenser. Can I use 12”x 8” rectangular ductwork? There is a possibility long time from now the cabin could increase in size to 770 sq ft. This is a 1 level cabin. I’ll be using 1 straight length of ductwork 36’ long. 1- 4’ branch to the restroom.

[@sriharshad6891]

why is a fan selected based on only index run pressure loss , what about all other pressure loss in other branches ? fan need to pump air through the other branches right /? like pressure loss of AB+BC+DE+EF+EH+HL

[@Backbencher_of_RUET]

Fitting loss in G-I direction should not be 0.36. I guess, 0.36 is the Fitting Coefficient. So, the fitting loss in G-I direction should be 2.65. Please correct me if I'm wrong. Thank you.

[@debrajpaul1861]

@EngineeringMindset - Why does the pressure through the dampers installed at the junctions have to have a pressure loss equivalent to the deficit b/w the index path loss and the loss through the branch terminating through a junction? Understand, there will be pressure loss on account of installing the VCDs but why does not exactly need to be the deficit to ensure designed flow through each branch? At the most, if the pressure loss through the damper is not exactly equal to the deficit but a little less than it, the air exiting through the branch connected to the damper will be supplying air at a bit higher than atmosphere. What's wrong in that?Pressure per metre of the duct was assumed as the same for all ducts / branches and not the actual pressure drop occurring along a branch. WIth different flow rates and diameters of the duct sections, this can quite be achieved so why is the need for the rest of the branches requiring to have a total pressure drop as that of the index path loss? Please explain?

[@debrajpaul1861]

I got the answer.🙂

[@Henrrych1999]

Is there any second part? What to account for when moving from the cross sectional area to the final duct size? What about the return vent? HHHEEEELLLPPPP

[@kouroshabady6526]

Do you know any free program to drawing the HVAC system? simple program are also helpful, tanks

[@alialmusallam3957]

as a general rule how many watts are needed per meter squared while doing a fast calculation for cooling load? Thank you

[@moinudheenmuhammed7514]

According to thump rule 1 TR for 100 sqft , and it will change as per the height

[@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?

[@ace8237]

I see the simscale simulation showing positive pressure leaving the fan but I don’t see how it accounts for the negative pressure the fan is creating as well. I’m a real world scenario this would be in an enclosed space and the air would be recycled and conditioned/cleaned. Would the static pressures or velocity shown here change if that was accounted for?

[@decapolis01]

I have never seen this method of calculating duct. It looks like a quick and simple method instead of calculating the Liters per second or CFM.

[@ddeonf8296]

Mantaps Good! Love This channel!

[@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

[@libertus8924]

I have a 420 square foot building with a furnace and a 19"x12" x 4 foot plenum. I bought 16"x8" rectangular ducts that run 24 foot long with six 6" vents. Are the ducts too big? Should I go with a 14"x8" or a 12"x8" duct size? I haven't installed the 16"x8" yet so I could exchange it. Thanks.

[@angelamarodelgado7016]

At point H, direction G-I, the correct value is 2.68, and not 0.36, can you confirm this error?

[@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?

[@barialayaziz9892]

Hello Dear Teacher. The tables that you are using for ducts, pleas write me the name of books. Thank

[@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?

[@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.

[@rohanvairagar6003]

MISTAKE:-in massflow rate formula delta T is in kelvin and you take delta T in degree celcius ..... 1:56

[@EngineeringMindset]

It makes no difference, its just the difference. 10-5=5, 210-205=5

[@Listen2MeMF]

Im still not paying you $100 an hour bro

[@grimlyolformig5859]

No one, who can afford and understands the value of services like this, says bro to punctuate their disparaging comments.

[@Listen2MeMF]

@@grimlyolformig5859 hey! I'm not black

[@pmcnally1989]

​@@grimlyolformig5859 it may be a tongue in cheek comment

[@grimlyolformig5859]

@@pmcnally1989 all tongue no cheek then.

[@cyberdude721]

Ok my question which is better, a furnace register that blows upward or one that blows across the floor as I have noticed blowing across the floor has it problems and furniture can block flow and create cold spots especially in smaller rooms so I guess my question is do I heat from top down if that makes sense(my old house has registers in the wall and blow across the floor)

[@mohammedmusaabansari8649]

How Celcuis converted to Kelvin in this video of temperature difference ?

[@vovalos]

This is fundamentally wrong at about minute 11. You are assuming that the pressure drop though all segments have to be the same? Why? Equal pressure method should have equal pressure to each grille, not equal pressure drop in each segment. As a result at the end all your branches end up having the drastically different pressure drops (from 5 to 12) and you start adding dampers. Why not save materials and put smaller ducts for sections that don't affect your largest pressure drop (C,F,I)? This will increase the pressure in your branches and you may avoid using dampers altogether. You have to be careful not to under size them too much though to keep your max 5m/s flow rate.

[@wongkingshun]

I think it is a torture as i dont understand the video and continue to keep watching becuase of my ocb

[@Listen2MeMF]

Is this real or a parody. Seriously im a diy about to do hvac ib my house😊

[@aaronpomeroy2579]

I’m an HVAC engineer. I WISH I saw this video when I first started. This would have been career changing believe it or not.

[@roxanecantillano5481]

Delta T = 8 degrees celcius but in the computation it become 8 kelvin. how is that happened? please explain it to me

[@davideyres955]

I’m not sure but I world guess that because it’s delta t it’s the difference between one temperature and another. If I remember my schooling Kelvin is the same a centigrade just starts a 0 at absolute zero so and is the same gap between the two different scales just bigger numbers in Kelvin.

[@rohitsuryawanshi8834]

where is the link for duct pressure loss chart?

[@sergio11010]

These videos are obsolete and fantastic explanations for refreshers on these in little things

[@traninhtoan7203]

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

[@ArmanKhan-jq1xk]

thanks for the video , can you share me this ppt ?

[@parthvaria4361]

How to do calculation for return duct??

[@zdan5791]

Do we size the unit by heat load or volume flow rate at main duct "A"? I am running into a situation that unit capacity is sufficient to the heat load, but the calculated volume flow rate at main duct "A" is more than the unit CFM. What do I do in this case?

[@zdan5791]

Also is it reasonable that we have that many tapers in the duct due to the size reduction based on the calculation? Is there some rule of thumb like with certain values we don't have to use tamper?

[@keyurshah5030]

Unit (Air Handling Unit) size… Fan shall be sized to deliver Dehumidified CFM (one get from heat load calculations) at resistance (expected pressure drop calculated from duct layout). Usually because of added safety factors and other reasons system-resistance is lower than the calculated system-resistance. For fixed speed fan motor AHU, one need to have/introduced opposed blade damper at AHU outlet to artificially increase system-resistance which in turn will reduce airflow. For Fan with VFD, one can opt to run it on lower frequency to reduce airflow to the design airflow. Hope your coil is designed to meet sensible and latent load as per heat load calculations. Hope I understood your question correctly and answer is aligned to be of some help.

[@rolandovillamiro1105]

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

[@patrickmartin9530]

calculation used for temperature change is 8 degrees then in the actual computation you used 8 kelvin?

[@EngineeringMindset]

Yeah so it's just the difference between the two temps, wouldn't matter if it was kelvin - kelvin or C - C it's still a difference of 8

[@almasum5939]

Nice video

[@almasum5939]

hello?

[@LeavenTaiwan]

VERY GOOD

[@hvacguy11]

To bad this was metric and I had no idea what was going on because of that lol

[@waheedbashirkhokharkhokhar4485]

very nice sir, HVAC&R ENGINEER from pakistan

[@EngineeringMindset]

Glad you enjoyed it

[@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.

[@igor.castro]

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

[@classified0178]

could you link me to the guide where to decide the air velocity?

[@deekshithns8491]

Sir, I have one query, When designing the HVAC supply duct system, After calculation of ASP from the manufacturer blower data (ESP- Device pressure losses). That ASP will become the pressure drop budget for the duct system. Now if we are designing the duct system with equal friction method based on FR calculated...and carrying out CFD analysis of designed duct, the solver fetches static pressure and total pressure data w.r.t our design. Now w.r.t previously calculated ASP which is our pressure drop budget, say some 0.4 inches of water gauge. Now inorder to check whether duct design is within the limits as per ASP in CFD analysis tools. which pressure drop should I need to consider ( it's a total pressure in the volume of air or it's difference in Total pressure at inlet to outlets, or it's a max static pressure developed in the air volume inside duct) kindly clarify

[@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?

[@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

[@GMartinez777]

How do you get the values for cooling and heating loads?

[@Kitt_lau]

Hi, how to calculate the heating load and cooling load? 🙏🏻

[@tebogoclayton6231]

can anyone send me the static pressure chart? great video.

[@yasuhiroy6585]

HI, I am a beginner, ducting for 2 story with basement in South Philadelphia , the land / house space is Wide 16 ' x Long 40 ' (feets) , what is the ducting dimension / size for main duct , [ 8"x16 ] or [ 8"x24" ] or..... is better ? because I do not know how to calculate it . thank you

[@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

[@civildk9077]

Question: Why are two story homes, fitted with 2 units, but not ducted to accommodate 'convection'? Heat going up, cold falling. Returns are on the same floors as ducts for each unit. WHY?

[@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

[@edunewton1386]

Hi, Please how we calculate the dynamic loss for damper, for example motorised damper as a fitting? Thanks

[@jeffshore682]

Any chance of doing a video with the antiquated English measurements that we use in the U.S.?

[@zoranpopovic4254]

nice video but its confusing because all air flow on the vents that i can buy are in m3/h (your is m3/s)

[@EngineeringMindset]

You can just convert them

[@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.

[@pattenbarham2878]

Can you do a video on the Velocity Reduction Method?

[@grootgrootings6781]

Hi sir, how about designing a multiple floor duct system (with 2nd floor and 3rd floor house). Is the main duct from the upper ground or lower ground?

[@shreddedskull666]

Depends on where your feeding it from, if you’ve got an RTU then it all comes down from above and is distributed through the building either directly or through VAV boxes, if you choose to have individual AHUs all throughout the building then they orginate from each floor the air handler is on, but then you’d also need to worry about condensing units and possibly chillers to aquire and it may not become a feasible option if you’re low on budget.

[@taylorpikor-zs3ym]

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

[@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

[@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?

[@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...)

[@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.

[@hindricksaironariola7056]

Good day Sir. May I asked what maybe the factors I should consider in computing cooling load by if I am going to use manual calculation? My problem is that when using danfoss coolerselector2 (software) I am getting a different values which has a very big discrepancy.

[@IceyJunior]

Hi Paul or any other engineer in M&E building engineering line, I have a question to ask you all about changing of duct size. Say a 500 (w) x 400 (h) mm duct, and I wanna change the height of 400 mm to 250 mm. I used the hydraulic diameter equation to calculate for the new width. However, when I compare the answer to the "duct calculator". It doesn't match with my calculation. My calculation shows a new width of 2000 mm whereas the "duct calculator" shows 850 mm. What assumption/mistake or anything other related things did I not take into considerations?

[@EngineeringMindset]

Probably the velocity, temperature or density. Use a sizer by an industry body or one approved by them

[@AKK105]

How do you determine the height and width of the duct?

[@etfc944]

Great video this can you make video on DX UNIT

[@Henrrych1999]

A dozen of universities and online schools emptying pockets for teaching this topics don't like your video.

[@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.

[@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?

[@abhishekpatra4723]

the intro music is irritating, change it. PLEASE.

[@EngineeringMindset]

There's no intro on new videos. We can't change old videos, KZbin doesn't allow it.