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

Hey there guys, Paul here from TheEngineeringMindset.com. In this video, we’re going to

be looking at ductwork systems for mechanical ventilation. We’re going to look at how to design a basic ventilation system

with a full worked example. We’ll also look at how

to calculate the losses through the bends, the tees,

the ducts and the branches, we’ll consider the shapes in the material that the ducts are made from

to improve the efficiency, and then lastly, we’re going

to look at how to improve the efficiency and optimize the design, using a freemium software for fluid flow simulation by SimScale. Methods of ductwork design, there are many different methods used to design ventilation systems, the most common ways

being velocity reduction, equal friction and static regain. We’re going to focus on

the equal friction method in this example, as it’s

the most common method used for commercial HVAC systems, and it’s fairly simple to follow. So we’ll jump straight

into designing a system. We use a small engineering

office as an example and we’ll want to make a

layout drawing for the building which we’ll use for the

design and calculations. This is a really simple building. It has just four offices, a

corridor, and a mechanical room. And the mechanical room is where we’re going to have the fan, the filters, the air

heaters or the air cooler. The first thing we’ll need to

do is calculate the heating and cooling loads for each room. I won’t cover how to

do that in this video, we’ll have to cover that

in a separate tutorial as it’s a separate subject area. Once you have these figures,

just tally them together to find which is the biggest load as we need to size the

system to be able to operate at the peak demand. The cooling load is

usually the highest load as it is in this case. Now we need to convert the cooling loads into volume flow rates, but to do that, we first need to convert

this into mass flow rates, we use the formula M dot

equals Q divided by CP, multiply by delta T, with M

dot meaning the mass flow rate, the Q being the cooling load of the room, CP is the specific heat

capacity of the air and delta T being the

temperature difference between the design air temperature and the design return temperature, just to note that we will use a CP of 1.026 kilojoules per

kilogram per kelvin as standard, and the delta T should be less

than 10, and in this case, we’re going to use eight degrees Celsius. We know all the values for this formula, so we can calculate the mass flow rate, and the mass flow rate is

really just how many kilograms per second of air needs

to enter that room. If we look at the

calculation for room one, we see that it requires

0.26 kilograms per second. So we just repeat that calculation

for the rest of the rooms to find all the mass flow rates. Now we can convert these mass flow rates into volume flow rates. To do that we need the specific volume or density of the air. We’ll specify that the air

needs to be 21 degrees Celsius, and we’ll assume that it’s going to be at atmospheric pressure of 101.325 kPa, we can look up the

specific volume or density from our air properties tables, but I like to just use

an online calculator as it’s much quicker. So we just drop those numbers in and we get the density of

air being 1.2 kilograms per meter cubed. You see that density has the units of kilogram per meter cubed,

but we need specific volume which is meter cube per kilogram. So to convert that we

just take the inverse which means to calculate

the density or 1.2 to the power of minus one, you can just do that in Excel

very quickly to get the answer of 0.83 meters cube per kilogram. Now that we have that we can

calculate the volume flow rate, using the formula V dot

equals M dot multiplied by V, where V dot equals the volume flow rate, M dot equals the mass flow

rate of the individual room and V equals the specific

volume, which we just calculated. So if we drop these

values in for room one, we get the volume flow rate

of 0.2158 meters per second. That is how much air it

needs to enter the room to meet the cooling load. So just repeat that calculation

for all the remaining rooms. Now we’re going to sketch

out our ductwork route onto the floor plan so

we can start to size it. Before we size that we need

to consider some things which will play a big role

in the overall efficiency of the system. The first point we need

to consider is the shape of the ductwork, Ductwork comes in round,

rectangular, and flat oval shape. Round duct is by far the

most energy efficient type and that’s what we’re going to use in our worked example later on. If we compare round

duct to rectangle duct, we see that a round duct

with a cross sectional area of 0.6 meters squared has

a perimeter of 2.75 meters, a rectangular duct with

equal cross sectional area of 0.6 meters squared, has

a perimeter of 3.87 meters. The rectangular duct

therefore requires more metal for its construction. This adds more weight

and cost to the design. A larger perimeter also

means that more air will come into contact with the material

and this adds friction to the system. Friction in a system means

a fan needs to work harder and this results in

higher operating costs. Always use round duct where possible although in many cases the

rectangular duct needs to be used as space is very limited. The second thing to consider

is the material being used for the ducts. The rougher the material, the more the friction it will cause. For example, if we had two

ducts with equal dimensions, volume, flow rate and velocity, the only difference being the material, one is made from standard galvanized steel the other from fiberglass. The pressure drop over a 10-meter distance for this example is around 11 pascals for the galvanized steel and

16 pascals for the fiberglass. The third thing we have to consider is the dynamic losses

caused by the fittings. We want to use the

smoothest fittings possible for energy efficiency. For example, use long radius

bends rather than right angles as the sudden change in direction, wastes a huge amount of energy. We can compare the performance of different ductwork designs

quickly and easily using CFD or computational fluid dynamics. These simulations on screen were produce using a

revolutionary cloud-based CFD and FEA engineering platform by SimScale who have kindly sponsored this video. You can access this software

free of charge using the links in the video description below, and they offer a number of

different account types, depending on your simulation needs. SimScale is not just

limited to ductwork design, it’s also used for data

centers, AEC applications, electronics design, as well as thermal and structural analysis. Just a quick look through their site and you can find thousands

of simulations for everything from buildings, HVAC

systems, heat exchangers, pumps and valves, to

race cars and airplanes, which can all be copied

and used as templates for your own design analysis. They also offer free webinars,

courses and tutorials to help you set up and

run your own simulations. If like me, you have some experience

creating CFD simulations, then you’ll know that

this type of software is usually very expensive, and you would need a

powerful computer to run it. With SimScale however, it can all be done from a web browser, as the

platform is cloud-based, their servers do all the work and we can access and design

simulations from anywhere which makes our lives as

engineers a lot easier. So if you’re an engineer,

a designer, or an architect or just someone interested in trying out simulation technology, then I highly recommend you

check out this software, get your free account

by following the links in the video description below. Now, if we look at the

comparison for the two designs, we have a standard design on the left and a more efficient design on the right which has been optimized using SimScale. Both designs use an air velocity

of five meters per second, the color represents the velocity with blue meaning low

velocity and red representing the higher velocity regions. We can see from the velocity

color scale and the streamlines that in the design on the left, the inlet air directly

strikes the sharp turns that are present in the system, which causes an increase

in the static pressure. The sharp turns cause a large amount of recirculation regions when the duct’s preventing the air from moving smoothly, the T section at the far end

of the main duct causes the air to suddenly divide and change direction, there is a high amount of backflow here which again increases the static pressure and reduces the amount of air delivery. The higher velocity in the

main duct which is caused by the sharp turns and

sudden bends reduces the flow into the three branches on the left. If we now focus on the

optimized design on the right, we see that the fittings used

follow a much smoother profile with no sudden obstructions,

recirculation or backflow, which significantly

improves the air flow rate within the system. At the far end of the main

duct, the air is divided into the two branches through

gentle curved T section. This allows the air to

smoothly change direction and thus there is no sudden

increase in static pressure and the air flow rate to these rooms has dramatically increased. The three branches within the main duct, now receive equal airflow, making a significant

improvement to the design. This is because an

additional branch now feeds the three smaller branches, allowing some of the air

to smoothly break away from the main flow and feed

into these smaller branches. Now that we have decided

to use circular ducts, made from galvanized steel, we

can continue with the design. Label every section of ductwork

and fitting with a letter. Notice we are only designing

a very simple system here so I’ve only included

ducts and basic fittings, I’ve not included things

such as grills, inlets, flexible connections,

fire dampers, et cetera. Now we want to make a table with the rows and columns

labeled as per the example on screen now, each duct and

fitting needs its own row. If the air stream splits

such as with a T section, then we need to include a

line for each direction. So just add in the letters

to separate the rows then declare what type of fittings or ducts that corresponds to. We can start to fill some of the data in. We can first include the volume flow rates for each of the branches. This is easy, it’s just the

volume flow rates for the rooms which the branch serves. You can see on the chart

I’ve filled that in now, then we can start to size the main ducts. To do this, make sure you

start with the main duct which is furthest away, then we just add up the volume flow rates for all the branches downstream from this. For the main duct G, we just

sum the branches L and I, for D, that’s just the sum of L, I and F, and for duct A then it’s

the sum of L, I, F and C, so just enter those into the table. Now from the rough drawing, we measure out the lengths

of each of the duct sections and the branches and

enter this into the chart, and now we can begin to calculate

the size of the ductwork. To do that we need a

duct pressure loss chart, you can obtain these from

ductwork manufacturers or from industry bodies

such as CIBSE and ASHRAE. I’ve included links to these guides in the video description

below so do check those out. These charts hold a lot of information, you can use them to find

the pressure drop per meter, the air velocity, the volume flow rate, and also the size of the ductwork. The layout of the chart

does vary a little, depending on the manufacturer,

but in this example, the vertical lines are for

pressure drop per meter of duct, the horizontal lines are

for volume flow rate, the downward diagonal

lines are for velocity, and the upward diagonal

lines are for duct diameter. We start sizing from the first main duct, which in this example is section A. To limit the noise in this section, we’ll specify that you can

only have a maximum velocity of five meters per second. We know that this duct also

requires a volume flow rate of 0.79 meters cubed per second,

so we can use the velocity and volume flow rate to find

the missing data on the chart. We take the chart and scroll

up from the bottom left until we find the volume flow rate of 0.79 meters cubed per second, then we locate where the velocity line is of five meters per second

and we draw a line across until we hit that, then

to find the pressure drop, we draw a vertical line

down from this intersection. In this instance, we see it comes out at 0.65 pascals per meter, so add this figure to our table. As we are using the equal

pressure drop method, we can also use this pressure

drop for all the duct lengths, so fill these in too. Then coming back to the

chart, we scroll up again and align our intersection

with the upward diagonal lines to see that this requires

a duct with a diameter of 0.45 meters, so we add

that to the table also. We know the volume flow

rates and the pressure drop so we can now calculate

the values for section C and then also the remaining ducts. For the remainder of the ducts, we need to use the same method. On the chart we start by drawing a line from 0.65 pascals per meter. We draw this line all the way up. Then we draw another line across from where our required

volume flow rate is, in this case for section C, we require 0.21 cubic meters per second. At this intersection, we draw a line to find the velocity and we

can see that it falls between the lines of three and

four meters per second so we need to estimate the value. In this case it seems to be

around 3.6 meters per second, so we add that to the chart. Then we draw another line

on the other diagonal grid to find our duct diameter, which in this case is around 0.27 meters, and we’ll add that to the table also. So just repeat that last process for all the remaining ducts and branches until the table is complete. Now find the total duct

losses for each of the ducts and branches, it’s very

easy and simple to do, just multiply the duct length

by the pressure drop per meter of 0.65 pascals per meter and do that for all the ducts

and branches on the table. Now we can start on the fittings. The first fitting we’ll look

at is the 90-degree bend between ducts J and L. For this we look up our lost

coefficient from the bend from the manufacturer or

from the industry body. Again link’s in the video

description below for these. In this example, we can see the coefficient

comes out at 0.11. We then need to calculate

the dynamic loss caused by the bend changing

the direction of flow. For that we use the formula

Co multiplied by rho, multiplied by V squared divided by two, where Co is our coefficient,

rho is the density of the air and V is the velocity. We already know these values,

so if we drop these figures in then we get an answer of 0.718 pascals, so just add that to the table. The next fitting will look at is the Tee which connects the main

duct to the branches. We’ll use the example of

the tee with the ID letter H between G and J in the system. Now for this we need to

consider that the air is moving in two directions, straight

through and also turning off into the branch. So we need to perform calculations for both of these directions. If we look at the air traveling

straight through first, we find the velocity ratio first, using the formula velocity

out, divided by velocity in. In this example, the air out

is 3.3 meters per second, and the air in is four meters per second, which gives us answer of 0.83. Then we perform another

calculation to find the area ratio. This uses the formula

diameter out squared, divided diameter in squared. In this example, the

diameter out is 0.24 meters, and the diameter in is 0.33 meters. So if we square them, we would get 0.53. Now we look up the fitting we’re

using from the manufacturer or the industry body, again, link’s in the video

description below for those. In the guides, we find two tables, the one you use depends

on the direction of flow, we’re using the straight

direction, so we’ll okay that one and then we look up each ratio

to find our last coefficient. Here you can see both values we calculated for between values listed in the table, so we need to perform a

bilinear interpolation. To save time, we’ll just use an online

calculator to find that, links to the site are in

the video description below. So we fill out our values and

we find the answer of 0.143. Now we calculate the dynamic

loss for the straight path with a tee using the formula

Co, multiplied by rho, multiplied by V squared divided by two. If we drop our values in, we

get the answer of 0.934 pascals so add that to the table. Then we can calculate the

dynamic loss for the air which turns into the bend. For this we use the

same formulas as before, velocity out, divided by velocity in, to find our velocity ratio. We take our values from our table and use 3.5 meters per second, divided by four meters

per second to get 0.875, for the velocity ratio,

then we find the area ratio, using the formula diameter out squared, divided by diameter in squared, and we use 0.26 meters squared, divided by 0.33 meters squared to get 0.62 for the area ratio, then we use the bend

table for the T section. Again, it’s between the

values listed in the table, so we have to find the numbers

using bilinear interpolation. We drop the values in to get

the answer of 0.3645 pascals, so just add that to the table too. Now repeat that calculation

for the other tees and fittings until the table is complete. Next, we need to find the index run. which is the run with the

largest pressure drop. It’s usually the longest run,

but it could also be the run with the most fittings. We find it easily by adding

up all the pressure losses from start to the exit of each branch. For example, to get from A

to C, we lose 5.04 pascals, for A to F, we lose 8.8 pascals, for A to I we lose 10.56 pascals, and for A to L we lose 12.5 pascal. Therefore the fan we use,

must overcome the run with the highest loss that

being A to L with 12.5 pascals, this being the index run. To balance the system,

we need to add dampers to each of the branches to

ensure equal pressure drop through all to achieve the

design flow rates to each room. We can calculate how much pressure drop each damper needs to provide

simply by subtracting the loss of the run from the index run. A to C is 5.04 pascals, which means that branch

C would need a damper, providing 7.46 pascals. A to F is 8.8 pascals which means that branch F would require a damper providing 3.7 pascals, and A to I is 10.56 pascals,

meaning that duct I, would require a damper

providing 1.94 pascals and that is our ductwork system. We’ll do another video

covering additional ways to improve efficiency in ductwork systems, but unfortunately we’ve run

out of time in this video. Okay guys, that’s it for this video. Thank you very much for watching. I hope you’ve enjoyed this

and it has helped you. If so, please don’t forget

to like, subscribe and share and also check out SimScale software. You can follow us on

Facebook, Twitter, Instagram, Google Plus, as well as our website, TheEngineeringMindset.com. Once again, thanks for watching.

Great video….. Thank you so much

very nice sir, HVAC&R ENGINEER from pakistan

American here…..metric was a little hard to follow….but otherwise a great video 🙂

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.

I love it, thanks!!

Is delta T is in Kelvin or Centigrade?

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

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

great video man as always

and congrats for 100k subs.

Intro sounds chiller 😍

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.

Thanks

Great video.

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

Off course we enjoy it .

Sure it helps us .

Thank you, genius .

This is why i cant do ductwork lol

⚠️

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

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.

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 ??

how did you able to give the velocity ?

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?

How do I determine how much to charge customer per BTU unit measured through BTU meter?

great video..really helpful.thanks engineeringmindset.

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

Thank You

Amazing videos seriously.

Awesome explanation. Really useful!!

Do you have more videos on ventilation duck sizing as mentioned in this videos?

Could you please clarify that : how to calculate armaflex air duct insulation thickness.

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?

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

thank so much for video,its very helpful, de argentina muchas gracias

great video which helps me a lot.

Very helpful

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

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.

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.

Hi in this video u mentioned about another video of how to calculate heating and cooling load. Is there a link? thnks

I am an mechanical engineering student and is interested in HVAC designing jobs like this can i know what will be the salary like for a designer ??

Is that a good decision

dude, that's very helpful .. thank you so much 🙂 !

how to find the duct pressure loss chart

It's super easy to design stuff!

You just take the signs off of it!

😀

Got it,use circular ducts instead of square ones.

I'm confused because you calculated by room load rather than the system chosen. I don't think they make 7.9K BTU air conditioning systems so why would you use those loads to design a duct system that has to be interfaced with a nominally sized system? Like 12K BTU or 18K?

For my house project, I've done a room-by-room load calculation (totals 9.5K) and I tried to follow along here for duct sizing, but I'm scratching my head because I don't see how this is going to work when I have to choose a 12K BTU system for the duct work to actually handle. Seems like I'm designing duct work for a 9.5K BTU system when I'm really going to have to put in a 12K system. Am I missing something obvious?

Great video this can you make video on DX UNIT

Is there a video on vav boxes? I need to know if the vav boxes also have a little coil that can add or remove heat, in addition to merely constricting or expanding airflow

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 YouTube.

Thanks for providing such fantastic resources for the industry.

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).

Great video. Really well explained!

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

choosing between rectangular and round shape is also driven by the cost of the duct isn’t it? using round shape may give you lower friction but cost you more in terms of the overall weight and space of the ventwork

thank you for the video…But how to find initial velocity i.e 5 meter per sec ? What are the recommended values?

Thanks! You are awesome. 👍

Why does V and M need a dot over them?

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

You’re amazing fam.

watch How

AIR HANDLING UNITSwork here: https://youtu.be/KCiv8IAUkh8How to do calculation for return duct??

how to get the velocity for A 5m/s?

Helpful and to the point explanation , thumbs up!

whats the link to the fitting tables?

Anyone know how to calculate minor loss for grille? What's the k value of grille?

Do you do system designs for residential

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

Hey Paul,

I am confused about the ESP and couldn't find anybody to explain to me the following 2 questions, I hope you can clarify them for me:

1- why would the static pressure drop when encountering resistance such as filters or coils when at the same time the dynamic pressure decreases (because the velocity of air is decreasing)? I thought that when SP decrease, the DP should increase.

2- why might a concealed FCU break down if installed without ducts?

thanks in advance and I hope you see my comment ^_^.

excellent video,,,

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 ?

Hi Engineering Mindset,

Your videos are so great, it help a lot for my work i would like to suggest if u can do a video on sizing a chiller for building.

THANK YOU

i love this video, thanks

Hi @theengineeringmindset

From where i can download the duct pressure loss chart ? and tee and fittings chart ? can you help ? i couldnt find it in your description below.

Hi,

i want to know what is method for doing duct sizing for square duct and rectangular duct ? can we use this method for rectangular duct ? and if we use then how should we consider duct height ?

Hi,

i want to know what is method for doing duct sizing for square duct and rectangular duct ? can we use this method for rectangular duct ? and if we use then how should we consider duct height ?

Hi,

i want to know what is method for doing duct sizing for square duct and rectangular duct ? can we use this method for rectangular duct ? and if we use then how should we consider duct height ?

great job

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.

but this is only for sensible load……

the total load should be the difference between enthalpies

Sir pls tell what is meant by heating load and cooling load??

amazing..

hI MAY I KNOW WHAT IS THE LINK FOR YOUR DUCT PRESSURE LOSS CHART?

U so much good and talent never giveup go ahead 😍😍🤗🤗 but this video so much fast …

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?

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

Damn we went from cave homes to surgical rooms. I didnt know we where so sensitive.

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.

Duct Pressure Loss Chart Please 🙁

I wish to translate this video on arabic language and the tables small

Every "air properties table" that I have and have searched up has given MUCH different values for the Cp of air. At about 70 degrees F, they all list values very close to cp = 1.005. You on the other hand, listed 1.026, which all my tables list that value when the air temperature is around 440 F… Is this an error? Did you forget a "0" before the "2"?

i actually use simscale what a peace of software

Love your videos but need U.S measurements

Hi,

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

Thanks

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.

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

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?

New subscriber here, great video

Thank you, for giving great and more easily understandable video

Good work .

I found your video to be very informative but It would be helpful (almost necessary) if you provided a link to the pressure drop chart. Its not easy to find the chart (so far its been impossible for me) with the units your using. I followed your calculations for my entire house as I am renovating and need to update my duct work, but now im stuck because the chart you reference is nowhere to be found, not even in the video description as you state in the video. it seems that the vast majority of charts available don't use the metric system but instead use imperial with the units: W.G./100ft, cfm, ft/min, Inch. and the ones that are in metric don't use Pa/m but instead use (mm H2O/M). I guess I could download one of those charts and just convert the Pressure drop from mm h2O/M to Pa/M, but it would be cool if I didn't need to.

Do you have a video that when you have a rectangular ducting instead of round ducting?

Amazing video btw. thanks!

Hello sir,

If I was to purchase a/c unit with more seer rating do I need to increase the duct size?

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