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

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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 (https://www.simscale.com/) 🏆🏆🏆 Create a free SimScale account to test the cloud-based simulation platform here: https://www.simscale.com/ With 100,000+ users worldwide, SimScale is a revolutionary cloud-based CAE platform that gives instant access to CFD and FEA simulation technology for quick and easy virtual testing, comparison and optimization of designs in several industries, including HVAC, AEC, and electronics. Discover more than 50 free on-demand webinars on different topics, from ventilation or data center design and wind load analysis to aerospace, F1, and sports aerodynamics here: https://www.simscale.com/webinars-wor... Read more about the benefits of using cloud-based engineering simulation and the SimScale Community here: https://www.simscale.com/product/pricing Find thousands of ready-to-use simulation templates created by SimScale's users which you can copy and modify for your own analysis: https://www.simscale.com/projects/ Book 1: https://amzn.to/2y3e2Lv Book 2: https://amzn.to/2KhTKD2 Book 3: https://amzn.to/2JwcoYo Bilinear interpolation: http://bit.ly/Bilinear-calculator Air properties calculator: http://bit.ly/2tyT8yp 👋 SOCIALISE WITH US 👋 ******************************* 👉FACEBOOK: https://facebook.com/theengineeringmindset/ 👉TWITTER: https://twitter.com/TheEngMindset 👉INSTAGRAM: https://instagram.com/engineeringmindset/ 👉WEBSITE: Http://TheEngineeringMindset.com 🙌 SUPPORT US 🙌 ******************************* 👉Buy Paul a Coffee: https://www.paypal.me/EngMindset 👉Bitcoin: 3Jb56ZZQ6qL7ymKL12VinNZNLCTrj8yHWp 👉Patreon https://www.patreon.com/theengineeringmindset 👉Stickers & Tshirts: https://goo.gl/M1PGrx 👀 Links - MUST WATCH!! 👀 ******************************* ⚡ELECTRICAL ENGINEERING⚡ 👉How electricity works: https://youtu.be/mc979OhitAg 👉Three Phase Electricity: https://youtu.be/4oRT7PoXSS0 👉How Inverters work: https://youtu.be/ln9VZIL8rVs 👉How TRANSFORMER works: https://youtu.be/UchitHGF4n8 👉How 3 Phase electricity works: https://youtu.be/4oRT7PoXSS0 👉How Induction motor works: https://youtu.be/N7TZ4gm3aUg 👉What is a KWH: https://youtu.be/SMPhh8gT_1E 👉How induction motor works: https://youtu.be/N7TZ4gm3aUg ❄️ CHILLER ENGINEERING ❄️ 👉Chiller Efficiency improvements: https://youtu.be/8x3MiO5XjhY 👉Chilled water schematics: https://youtu.be/ak51DHAiuWo 👉Chiller crash course: https://youtu.be/K0xAKzdROEg 👉Chiller types: https://youtu.be/gYcNDT1d30k 👉Chillers/AHU/RTU: https://youtu.be/UmWWZdJR1hQ 👉Water cooled chiller Part1: https://youtu.be/0rzQhSXVq60 👉Water cooled chiller Part2: https://youtu.be/3ZpE3vCjNqM 👉Water cooled chiller advanced: https://youtu.be/QlKSGDgqGF0 👉Air cooled chiller: https://youtu.be/0R84hLprO5s 👉Absorption Chiller : https://youtu.be/Ic5a9E2ykjo 👉Chiller/Cooling tower/AHU: https://youtu.be/1cvFlBLo4u0 👉Chiller flow rate: https://youtu.be/tA1_V6-dThM 👉Chiller fault troubleshooting: https://youtu.be/Zu0LVVNNVSw 👉Chiller COP calculation: https://youtu.be/h5ILlZ8nyHE 👉Chiller cooling capacity calcs: https://youtu.be/BZxXIdxVKeY 👉Chiller compressors: https://youtu.be/7Bah__spkTY 👉Chiller expansion valve: https://youtu.be/dXiV5YzTZQ4 👉Chiller surge: https://youtu.be/DQK_-vxObiw 👉Chiller condenser: https://youtu.be/p5uuPsyqnwU 👉Chiller evaporator: https://youtu.be/W3w7FpX9j9k 👉Chiller compressor centrifugal: https://youtu.be/PT0UIqAGacg 👉Chiller cooling capacity: https://youtu.be/f-N4isgQRGQ 🌡️ HVAC ENGINEERING 🌡️ 👉HVAC Basics: https://youtu.be/klggop60vlM 👉Boilers/AHU/FCU: https://youtu.be/lDeuIQ4VeWk 👉How Heat Pump works: https://youtu.be/G53tTKoakcY 👉Heat pumps advanced: https://youtu.be/G53tTKoakcY 👉Fan Coil Units: https://youtu.be/MqM-U8bftCI 👉VAV Systems: https://youtu.be/HBmOyeWtpHg 👉CAV Systems: https://youtu.be/XgQ3v6lvoZQ 👉VRF Units: https://youtu.be/hzFOCuAho_4 👉Cooling load calculations: https://youtu.be/0gv2tJf7nwo 👉Pulley belt calculations: https://youtu.be/yxCBhD9nguw 👉Pump calculations: https://youtu.be/99vikjRrlgo 👉Fan and motor calculations: https://youtu.be/rl-HQRzL-kg 👉HVAC Cooling coils: https://youtu.be/oSs-4Ptcfhk 👉Cooling towers: https://youtu.be/UzHJWNL2OtM ⚗️ REFRIGERATION SYSTEMS 🌡️ 👉How refrigerants work: https://youtu.be/lMqoKLli0Y4 👉Thermal expansion valves: https://youtu.be/oSLOHCOw3yg 👉Refrigeration design software: https://youtu.be/QqP5aY6liAg 👉Design refrigeration system: https://youtu.be/TPabv9iDENc 👉Reversing valve: https://youtu.be/r8n1_6qmsKQ 👉How A/C units work: https://youtu.be/Uv3GfEQhtPE 🌊 HYDRONICS 🌊 👉Primary & Secondary system: https://youtu.be/KU_AypZ-BnU 👉Pumps: https://youtu.be/TxqPAPg4nb4 👉Pump calculations: https://youtu.be/99vikjRrlgo 💻 DATA CENTERS 💻 👉Data Center cooling: https://youtu.be/xBxyhxmhigc 🎬 DOCUMENTARY 🎬 👉WW2 Bunker HVAC engineering: https://youtu.be/xEzz-JkPeLQ
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Text Comments (70)
The Engineering Mindset (3 months ago)
*Found this super helpful?* buy Paul a coffee to say thanks: PayPal: https://www.paypal.me/EngMindset These videos take a long time to make. Help support us through Patreon with just *$2* https://www.patreon.com/theengineeringmindset
Rolando Villamiro (8 days ago)
thank you for this video!!! it's very helpful!
Icey Junior (9 days ago)
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?
Probably the velocity, temperature or density. Use a sizer by an industry body or one approved by them
HVAC Azerbaijan (17 days ago)
Could you please clarify that : how to calculate armaflex air duct insulation thickness.
teoscott1 (27 days ago)
Awesome explanation. Really useful!! Do you have more videos on ventilation duck sizing as mentioned in this videos?
Yes have a look at out channel https://www.youtube.com/channel/UCk0fGHsCEzGig-rSzkfCjMw/videos
Byron JONES (28 days ago)
Amazing videos seriously.
riegi nelmida (1 month ago)
Thank You
kamlesh tiwari (1 month ago)
dear sir can u clear one thing when u were calculating for bend and other dynamic loss which is actually loss due to momentum change or velocity pressure loss means minor loss can u clear weather this is the only loss bend will generate or do we have to calculate friction loss in bend length separately which is considerd as major loss
ryan rance (1 month ago)
great video..really helpful.thanks engineeringmindset.
moumesh roy (1 month ago)
How do I determine how much to charge customer per BTU unit measured through BTU meter?
moumesh roy (24 days ago)
+The Engineering Mindset If we work out this way then every building might have different cost. Is there an industry standard? How to understand from customer standpoint if he is not being taken for a ride with the costs?
Work out costs to operate, maintain, replace, profit
Icey Junior (1 month ago)
Hi Paul, the duct loss graphs you showed is it plotted from the pressure loss equation for fully developed flows (also called the Darcy-Weisbach equation)? Also, in this case gravitational effects are not affect the air in the duct as the duct is horizontal. What if some part of the duct is vertical? If so will this change the way of calculation as shown in this video? Also, when using this equal friction method, are you assuming that the pressure loss per meter length is constant? Also, will you be showing the other 2 method as mentioned in the early part of the video?
Icey Junior (9 days ago)
+The Engineering Mindset I dunno about others, but I certainly do.
Hello I'm actually not sure as the charts are from manufacturers and industry bodies, you would need to check with them. These are standard design guides for horizontal, vertical needs more calcs. I might cover the others it depends how well this video does and of there's a lot of interest.
Ttrucker (1 month ago)
Hopefully Sims 4 Nerds Expansion Pack comes out soon so build mode requires realistically engineering electrical, water, ducts and gas if you choose gas appliances in homes you build so these videos would be useful! Seriously I actually want that because it would make time spent watching this actually useful and in Rollercoaster Tycoon I hate killing guests. My fun in that game comes from engineering safe and exciting rides with maximum through put and large profit for at least a decade. That is why I always use block brakes on my rollercoasters becasue it is more realistic as real coasters have similar safety systems and it is harder to keep the trains from delaying each other. It is possible to space trains out far enough with block brakes so they only stop in the station. I also wish this channel would show rollercoaster engineering at least with track rides in OpenRCT2. I might actually be helped by that because only recently I got into the OpenRCT2 and improved on my ride designing in cost, space, safety, keeping excitement up while keeping intensity down so I might still learn better ways of ride design from this channel.
Jesus Carl Sancheja (1 month ago)
how did you able to give the velocity ?
Jesus Carl Sancheja (1 month ago)
did you assume the 5 meters per seconds velocity?
It was explained in the video, don't skip. If you know the volume flow rate and the cross sectional area, then you can find the velocity
Rodger Salem (2 months ago)
im new to the design field .. shouldn't 8 C = 281 K ??? why did you take it in the equation with the value of 8 K ??
Rodger Salem (2 months ago)
okay .. thank you .. i got what you mean .. great video .. now im searching among your collection about the cooling and heating loads calculations.
The Engineering Mindset (2 months ago)
ok, its temperature difference. so it doesn't matter if you use C or K there is still a difference of 8 between the hot temperature and cold temperature. arbitrary example: 9*c - 1*c = DeltaT of 8c. and equally 282K - 274K = 8K Its just the temperature difference you want to design to, regardless of the temperature you'll use
Rodger Salem (2 months ago)
at the min.2.08 you mentioned the delta T should be less than 10 C and you took it 8 C then at 2.18 in the equation you used it for 8 K
The Engineering Mindset (2 months ago)
Can you include the time stamp where this occurs
James Runyon (2 months ago)
a bit dry for me as i only engineer my house for fun. (computer guy by trade) im sure if i wanted to do all of the calculations, it would be super accurate and helpful. your target audience might be the super dry and calculatey, so that might be just fine. ill watch a few more.
HVAC Guy (3 months ago)
This is why i cant do ductwork lol
Off course we enjoy it . Sure it helps us . Thank you, genius .
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
Keith Hogan (4 months ago)
Great video.
Khaleej Kha (4 months ago)
Thanks
Jason Anderson (4 months ago)
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.
YASIN ARAFATH (4 months ago)
Intro sounds chiller 😍
hvac officail (4 months ago)
great video man as always and congrats for 100k subs.
Tiago Ferreira (4 months ago)
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
The Engineering Mindset (3 months ago)
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
Alexander (4 months ago)
Thank you so much for this helpful video. Can we request a video explaining what pressure drops in ducts and pipe systems mean? I tried searching these online and in textbooks but couldn't understand it. Hopefully, with your teaching ability I may be able to understand the subject. Please reconsider.
The Engineering Mindset (3 months ago)
Your put work into a pump or fan so that it can create pressure. This pressure is the driving force for the fluid (water or air etc) the pressure always tries to reduce, when there is a an opportunity for pressure to escape to a lower pressure such as through an opening or grille, then the fluid will flow to this. As it flows it hits obstructions and experiences resistance. This wastes the energy and will reduce the pressure as its converted to kinetic energy.
lucas serra (4 months ago)
Was the cooling load provided in the beginning of the video considered sensible load? Because "m=Q*cp*dt" refers Q to sensible load
Mohammed Agader (4 months ago)
Is delta T is in Kelvin or Centigrade?
The Engineering Mindset (4 months ago)
Makes no difference when its delta T. Arbitrary example 18*c - 10*c = DT of 8*c the equivalent in kelvin (just add 273.15) so 291.15K - 283.15 = DT of 8K
Juancho Pland (4 months ago)
I love it, thanks!!
Yosef Bisk (4 months ago)
Awesome sauce!
Manolis Theofilos (4 months ago)
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.
Postwarmage28 (9 days ago)
Manolis Theofilos well part of that is having sales people who can actually sell the work properly . Other part is not every customer will pay the money for things to be done properly. I am not doing anything without getting paid . So I have rough estimates of what my ducting systems should cost based on system size . If a customer chooses me then I’ll go back and do my room by room calculations but I won’t blow my full load unless I’m getting the job it’s plain and simple . You get what you pay for . I deal with/over come this objection regularly with no issue
We usually have a contract drawn up before we begin work. Either fee or hourly based.
Mushroom Castle (1 month ago)
Manolis Theofilos I do the calculations after I get a deposit.
James Runyon (2 months ago)
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.
Manolis Theofilos (4 months ago)
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.
Trisha Hilton (4 months ago)
American here.....metric was a little hard to follow....but otherwise a great video :)
Ttrucker (1 month ago)
Just modernise then.
The Engineering Mindset (4 months ago)
Hmmmm nice idea, I'll keep it in mind for next time
Trisha Hilton (4 months ago)
The Engineering Mindset awesome thank you!! Just contemplating, maybe you could show the conversion on the screen but not necessarily say it? I REALLY enjoy your videos, they help out so much!! Keep em coming!!
The Engineering Mindset (4 months ago)
I try as much as possible to include both units but this video just went on for too long so unfortunately had to trim it back and default to metric. The method is the same for both, just the units are different.
very nice sir, HVAC&R ENGINEER from pakistan
The Engineering Mindset (4 months ago)
Glad you enjoyed it
Arif Mohamed (4 months ago)
Great video..... Thank you so much
jorge beato rodriguez (4 months ago)
Great video!!!
tehsimo (4 months ago)
air is 1.2kg per metre cubed???
The Engineering Mindset (4 months ago)
Sounds surprising but there's a lot of water in air which gives it mass. The density changes with temperature and pressure.
Arth Patel (4 months ago)
That is the density of air. 1 metre cube volume of air will weigh about 1.2 kg at 21 degrees and atmospheric pressure. :)
Bernhard Jordan (4 months ago)
16:58 -> why a damper? couldn't be calculated a thinner section duct with the same effect and less material used ?
Ian Powell (4 months ago)
Dampers are far superior and offer long-term system control/adjustment.
Manolis Theofilos (4 months ago)
Bernhard Jordan Yes you can but circular duct comes in standard diameters and it is usually stock item. If you want an odd size you will have to pay extra and deal with the lead times. With rectangular duct you can make any size you want to achieve the same pressure drop. However, you might have to reduce your duct size a lot and then the velocity becomes too big, hence noise in the system. Dampers provide much more control when you are commissioning the sytem.
John Miranda (4 months ago)
Great video. Just one question is there a standard basis for the maximum 5m/s velocity that you chose?
Manolis Theofilos (4 months ago)
Depends on the application (restaurant, office, hospital etc) if it is a main run or a branch etc. As a rule of thumb, dont go over 9m/s as you will get excessive losses due to friction and noise. You will need to refer to the relevant industry body for guidelines.
The Engineering Mindset (4 months ago)
Industry bodies ASHREA and CIBSE make recommendations in their guides for velocity to limit noise. Check the book links in the video description
No Never (4 months ago)
ay lmao

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