How to Design Duct Work for a 3 Ton Air Conditioning system

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  • Опубликовано: 26 сен 2021
  • Ductwork design for a 3 Ton air conditioning unit.
    Have you ever wondered if your ducts are sized right? Follow along to get a crash course in duct design.

Комментарии • 177

  • @teachmeeverything3344
    @teachmeeverything3344  Год назад +23

    Thanks for all the love guys. I'll be straight with you, I uploaded these videos then life got busy and to the backburner it went. I was pleasantly surprised to see so many views and subscribers when I remembered about this channel. I'll put some time in to answer your questions and start making some more videos.

    • @noneofurbus3339
      @noneofurbus3339 10 месяцев назад

      1:10

    • @noneofurbus3339
      @noneofurbus3339 10 месяцев назад

      13:20 13:21

    • @richardlong5482
      @richardlong5482 8 месяцев назад +2

      Dude thanks a million!! I have stressed about this project, never done it before, but you really helped me understand how to build a quality balanced system.....you're a life saver!

    • @pastorlee7908
      @pastorlee7908 8 месяцев назад

      I couldn't agree more! @@richardlong5482

    • @skytiger6671
      @skytiger6671 2 месяца назад

      My 24x48 house using 3 ton, but starting in the middle 28-8 ying out to on each side reducing to 20-8 will this be enough reducing? 3 bed 1 bath large kitchen and LivingR on one end.

  • @ClarkeLSmith
    @ClarkeLSmith 2 года назад +6

    This is an amazing explanation of how to design and HVAC ductwork system and how the reduction of the trunk size allows you to push more air to other rooms farther away from your system. Excellent!!!

  • @amolbhagwat6816
    @amolbhagwat6816 6 месяцев назад

    This video is amazing and is answering lot of my basic questions about duct work planning. 👏👏

  • @joshbibler
    @joshbibler 2 года назад +13

    I just wanted to comment and say thank you for making this video. I've watched dozens of videos the last few days about this subject as I'm redoing some old ductwork in my home and adding a few new ducts as well. The calculations for reducing the trunk to increase pressure was very helpful.

  • @Michael-fp7so
    @Michael-fp7so 10 месяцев назад +1

    This is one of the best explanations on this topic I’ve found!👍 Good shit bro , preciate you!

  • @TheAbdallah89
    @TheAbdallah89 Год назад +1

    excellent job explaining everything in details. I'm a Mechanical engineer by the way and currently doing HVAC Service residential. I really enjoyed the Video. thanks a lot.

  •  2 года назад +2

    Thanks so much. You clarify lots of questions. I will design my 3.5 TON ductworks for an AirBNB place with this helpful info. Thanks again.

    • @robertsmith2956
      @robertsmith2956 Месяц назад

      Don't want working AC, so they will leave.....

  • @kathrynpe1
    @kathrynpe1 6 месяцев назад

    Thank you, thank you, thank you. My all male coworkers are cool and all but only so helpful. This info isn’t a fly by tutorial or something that in passing one can quickly grasp.
    But your video and my duct calculator will definitely be a gem moving ahead.
    God bless you!

  • @WarrenHenry
    @WarrenHenry 10 месяцев назад

    Thank you for posting this. For laypeople like myself this is valuable information

  • @IADHDD
    @IADHDD Год назад +1

    One of the best videos I have watched. Very clear and easy to understand. I really enjoyed your video and I will watch it at least 10 times more lol

    • @trueforum378
      @trueforum378 9 месяцев назад

      Limit of watching it is 5 times per person. Please!

  • @sergioramirez9025
    @sergioramirez9025 3 месяца назад

    Sir this by far is the best video ever explained 👏 thank you so much 🙏

  • @FooDaki
    @FooDaki Год назад +1

    Thank you for the video , excellent explanation

  • @jeffdeluca1153
    @jeffdeluca1153 Год назад +8

    I worked in an HVAC dept years ago doing this stuff. You have done an excellent job of explaining and re-educating me on this topic. Well done!

  • @BandofBrothersSpike
    @BandofBrothersSpike 2 года назад +2

    Keeep the vids coming boss they’re great especially hvac related

    • @teachmeeverything3344
      @teachmeeverything3344  Год назад

      Thank you. I am jumping back into it, life kind of swallowed me up this year.

  • @crackerjack2010
    @crackerjack2010 2 года назад +2

    very good explanation on calculations

  • @hubercats
    @hubercats Год назад

    Excellent video! Thank you.

  • @twochickshomestead3439
    @twochickshomestead3439 Год назад

    Best video I have found!

  • @will-smith-nh
    @will-smith-nh Год назад

    Excellent video.
    Thank you.

  • @pastorlee7908
    @pastorlee7908 8 месяцев назад +1

    Very, very informative! I now can feel totally comfortable designing my own. Thanks so MUCH!!!

  • @AngelofOntario
    @AngelofOntario Год назад

    Wow, that was an AWESOME explanation & AWESOME drawings!!! I’ve been wondering how they size ducts as I’ve been thinking about how to change how our 2 bedrooms are heated, to make it more efficient (don’t ask, previous DIY owner). I LOVED THIS video! THANK YOU!!! Your explanations as you go along are very easy to follow & understand, while being thorough! Not everyone has that gift.
    Makes me also better understand how potable water plumbing is sized too. And possibly how to get more velocity at my furthest faucet!
    Do they have the same slide charts for water pipe sizing???
    Also, in residential heating with a natural gas, forced-air furnace, I use grate filters at the points of exit into the rooms to cut down on winter house dust. And I change them monthly. Is that stressing my heating system?

  • @elijahgoodman3140
    @elijahgoodman3140 Год назад +3

    Excellent job filling in the blanks I've had designing a duct system. I've always known about keeping velocity high, but what I didn't know was any velocity under 600 fpm was the point you needed to downsize ductcto keep static up. Thanks alot, truly.

  • @pineychristian
    @pineychristian 2 года назад +30

    Good video.. at least it gives an idea to people to see how much time is needed for people like me and millions of others need to design a duct system or entire HVAC system only to hear complaints about the pricing. There is a lot time need to design and build a material list to properly quote customers. This is the stuff that goes on behind the scenes at night when we don't get to spend time with our loved ones to make money .....

    • @chuckpugsley759
      @chuckpugsley759 Год назад

      Whiney prepper, count your blessings that you have a job.

    • @teachmeeverything3344
      @teachmeeverything3344  Год назад +5

      Truer words have never been spoken. When I owned my company the divorce rate for owners of HVAC companies was about 30% higher than the national average. There is a lot of blood, sweat, tears and mental exhaustion that goes into the trade. I have a deep respect for anyone tackling it and family life simultaneously.

  • @Parabellum-X
    @Parabellum-X Месяц назад

    This is my favorite RUclips video.
    Seriously.
    I've probably watched it about 20 times so far, just trying to get this information embedded into my brain. I've watched COUNTLESS videos here on RUclips about Duct Design, Sizing Ductwork, Calculating CFMs, etc.
    You name it.
    But this video in particular, in regards to the specific information that I am looking for, has been the most informative.
    Hands down.
    (I graduated college 2yrs ago (for HVACR), and, although I have performed a few change-outs and NUMEROUS service calls, I feel like my next step to advancing as an HVAC Technician is to learn how to calculate heat loads and unit sizes, and sizing ductwork.)
    Thank you so much, @teachmeeverything3344, for the time and consideration that you have taken out of your busy schedule to produce such wonderful content.
    And thank you SO MUCH for not playing annoying rap or elevator music throughout the entire video. 😏

  • @will_hunt_music
    @will_hunt_music 7 месяцев назад +1

    Awesome tutorial and great detail! Thanks! Only thing that would have been nice to add is notes on where/how to put the return ducts

  • @oindigenous9990
    @oindigenous9990 2 года назад +1

    Great video, New subscriber!!!

  • @ianwalbert8727
    @ianwalbert8727 2 года назад +1

    great video

  • @maxrovira7315
    @maxrovira7315 Год назад

    Thanks you for your time and for great teaching to be able to carry my out my project

  • @MadMotorDoc
    @MadMotorDoc Год назад

    Duct calculator a must ! Just started doing my homework on this stuff , explained & understood everything but the lenghts of each trunk runs before having to reduce ? 8"x 24" X ?. Im converting an abandoned hydronic on slab to forced air through attic.

  • @trentongibson4417
    @trentongibson4417 Год назад +2

    Would love to see a heat load calculation from scratch or even a mock one . I know people's software that they will use will be different but the process should be very similar thanks

  • @cookingblue22
    @cookingblue22 Год назад +2

    VERY informative and helpful lesson for the DIY person out here. I am curious, however, how the length of each section of duct affects the calcs and performance? Thinking shorter runs the better, but what do I know??? Also would love to see your process for designing the return side as well! TERRIFIC video...thanks so much!!!

  • @trueforum378
    @trueforum378 9 месяцев назад +2

    Great video! Question: how do you calculate the. LENGTH OF DUCT? example your 8x28? How far does this rectangular duct go?

  • @yoelocuba5900
    @yoelocuba5900 Год назад +1

    It is a good explanation. How do you size return air duct? Can show me please.

  • @AdamMarsh-vz2iw
    @AdamMarsh-vz2iw 7 месяцев назад

    Great video. Question is if you were to add zoned heating to this or any system would it affect or change this setup. I'm particularly wondering how it would affect a 2 zone system where you had upstairs and downstairs on two different zones? Do you need to change a bunch to account for flow and CFM, or is that why a bypass is added somewhere in the system to allow for limited flows? thanks for any help or explanation on that.

  • @centrumsolutions4744
    @centrumsolutions4744 Год назад

    Thanks for the this video. Are those room CFMs total equivalent length and friction rate? Also, are they based on ASP or?

  • @maxa9246
    @maxa9246 3 месяца назад

    Dude, make the next one the cold air return! :-) Great Video.

  • @ironmike7160
    @ironmike7160 11 месяцев назад

    Yup. Have to transition smaller each section to keep equal amount of velocity of airflow. I worked HVAC for 5 years.

  • @r.t.7925
    @r.t.7925 2 года назад

    Good info .Thanks

  • @michaelmorassi4953
    @michaelmorassi4953 10 месяцев назад

    Nice video. Noticed you used a .08 FR for the main trunk line, but no the branches to the individual rooms.

  • @austindearman2296
    @austindearman2296 2 года назад

    I partially closed my registers in certain rooms to redirect flow to the larger rooms where the air is needed more. Then proceeded to drive screws into the registers so they can't be adjusted when people walk across them or the kids try to mess with them.

    • @Je1gonzalez
      @Je1gonzalez 2 года назад

      You don't have volume dampers on your collars?

  • @rickcantu4501
    @rickcantu4501 Год назад

    Hey brother great video very good explanation , I live in Texas and we usually only use 1 sheet a duct board to make plenum and branch every run with flex. That’s 95% of Texas. Does this also work in that kind of designs?
    I’m a service technician don’t really do duct designing or manual J or D

  • @thedahlins
    @thedahlins 11 месяцев назад +1

    Thank you! Your calm, clear way of describing this is very informative! And along the way, you give us a tutorial in how to use a duct calculator. Much appreciated! If you have time to do another video, would you describe how to determine CFM's for various rooms, optimum register placements and the pros and cons of hard duct vs flex duct. I'm about to do a job for a client where the exterior wall of the living room faces south. The room has a vaulted ceiling, where the ridge beam prevents running ducts above the windows facing south. An option is to place registers high on the north wall in attempt to get air movement up and over to the windows and the south wall. The house is on a slab. Any thoughts would be appreciated! The layout of the room is similar to the 300 cfm room in your drawing, with the ridge beam running the length of the room.

  • @romanh5066
    @romanh5066 Год назад +1

    GREAT VIDEO. QUESTION: IF THE VELOCITY FOR METAL IS AROUND 800-1000, WHAT IS THE RANGE FOR BRANCH FLEX DUCTS?

    • @teachmeeverything3344
      @teachmeeverything3344  Год назад +1

      Typically around 600 FPM anything more will result in whistling and wind noise from the registers.

  • @hvacando5609
    @hvacando5609 2 года назад

    Is there a chart or pdf that shows the El for every single fitting? If so can you please let me know? Also can I find out the El for a specific fitting by calculating myself?

  • @billmiller5075
    @billmiller5075 2 года назад +1

    Good job

  • @jessicawang7095
    @jessicawang7095 Год назад

    Thank you so much ,
    What will be the recommended cold air return size in this design, if you use only one (including length, how far )

    • @teachmeeverything3344
      @teachmeeverything3344  Год назад +4

      I'm working on the return air video now. Keep an eye out for it soon. In the video I am doing both a room return and central return.

  • @juanrafaelsoto9342
    @juanrafaelsoto9342 2 месяца назад

    Excellent thanks

  • @donaldpape1435
    @donaldpape1435 Год назад

    Where are you getting your friction loss calculation from.... Rule of thumb? TEL,ASP,ESP? Plus loss per 100' of duct. I do love that slide rule though.

  • @felixmilburn4594
    @felixmilburn4594 2 года назад +2

    Great video, can you do a video for the return using this project/example as the guide?

    • @Martin-py4kx
      @Martin-py4kx 2 года назад

      I would also love to see this aswell!
      This was a very educational video, and I may look into learning this professionally to expand my skills in the trade

    • @Je1gonzalez
      @Je1gonzalez 2 года назад

      Did he ever make a video for the return?
      I would like to see it

    • @jesse4553
      @jesse4553 Год назад

      Me too!

  • @armintahoori6524
    @armintahoori6524 11 месяцев назад

    Very good 👍

  • @IADHDD
    @IADHDD Год назад

    I do have a question for you, I am installing a Mini-Split Concealed Duct system (1800 BTUs) which if I use the "400 CFM per 1 ton", it will be 720 CFM system. However, the indoor unit has 3 speeds (H/M/L) and the CFMs are 529/450/370 CFM. I am not sure what CFM I should use as a starting point to design the duct? Do I design it for 720 CFM which is the 18K BTU, or should I use the supplied CFM for the indoor unit? Even if I was to use the CFM for the indoor unit, am I supposed to use the H or M or L?

  • @chrisw4562
    @chrisw4562 Год назад +1

    Thank you for the great video. I am wondering, though, does the calculation of the pressure drop not need to take into account the length of the ducts going to each room? The calculator says pressure drop at 100 feet length, but most of the ducts appear to be 15-20 feet long. In my house, the duct length varies from under 10 feet to 40 feet, and the result is artic winds blowing in one room, while the other only gets a light breeze. It seems to be designed wrong and I want to correct that, but wonder how to calculate the proper duct sizing vs. length

  • @RichardT123456789
    @RichardT123456789 2 года назад

    Hello, How would you calculate a mobile home split system with an inside down flow air handler 3 ton . No return . The Mobile home is 16X80 single wide with 8 vents total. The original duct is the rectangular sheet metal, and it is degrading.The mobile home is 1999 model . The local supply shops do not have the sheet metal available & I am considering using Flex duct & I am not sure what size or may I even use flex duct in replacing the sheet metal .
    Thank you

  • @riazmalik2956
    @riazmalik2956 2 года назад +1

    Excellent explanation. How much the ductulator cost. Very handy and quick way

    • @teachmeeverything3344
      @teachmeeverything3344  Год назад +1

      You can get the Super Cool Slide rule from their website or on Amazon. They also have a free app.

  • @HVACKnowItAll
    @HVACKnowItAll 2 года назад +6

    Did you calculate your TEL and ASP to get your
    0.8 fricton rate or are you using a rule of thumb?

    • @edwardjanowiak
      @edwardjanowiak 2 года назад +2

      I’d like to see that part explained also 🤷🏾‍♂️

    • @alexzapata692
      @alexzapata692 2 года назад

      Ditto lol

    • @joshuaseaton4526
      @joshuaseaton4526 2 года назад +1

      He is using rules of thumb with the ductulator. Could be correct, but also could be very wrong.

    • @teachmeeverything3344
      @teachmeeverything3344  Год назад

      @@joshuaseaton4526 True, .08 is pretty typical, but not always exact. This house is also completely fictitious and the air volume requirements are made up.

  • @vqgang3575
    @vqgang3575 11 месяцев назад

    Would it be better to put a 4 ton or 3.5 to reduce the amount of reducing plenums u add ? or would u have to use a 3 ton due to the sq ft of the home ?

  • @isaiahwalker4065
    @isaiahwalker4065 Год назад

    Thank you

  • @helipadny1
    @helipadny1 Год назад

    Probably a stupid question.. My air handler ( 2ton system) will be in the middle of the house. most of the load will be on one half ( 500 cfm's) and the rest for the other half.. Do I size the trunks coming off the plenum (tee) accordingly?? 500 for one side and 300 for the other. or is one a one size trunk ( 800cfm) straight down the middle and just branch off from there?? thx!!!

  • @HobbyOrganist
    @HobbyOrganist Год назад

    My problem is my house never had central heat or A/C and I put a furnace in the basement and did the ducts as best I could with 6" round, but the ceiling is only about 6'4 in the basement and the layout is a cross-T with 2 valleys on the roof, that means the floor joists run one way in one part of the house and 90 degrees the other way in the rest, plus a main support beam that sticks down about 4" where the two joist systems meet. My floors are also porcelain tile and I'm not cutting more holes in the floors!
    Going to the attic is out of the question with ceiling vents- I have R100 insulation up there and the access is a TINY hatch barely big enough for me to squeeze thru and it takes a 10' ladder to reach it.
    I want to put a new furnace and rect ducts in

    • @teachmeeverything3344
      @teachmeeverything3344  Год назад

      The ceiling height in the basement can be hard to work with. Sometimes you have to decide one or the other (correct and adequate duct sizing or headroom). As I see it you have a couple of options. A ductless system without duct would be at the top choice, this eliminates the need for vents when you use the highwall units (or other non-ducted options) second would be a short depth duct either custom made or custom ordered, probably 6". Sometimes you have to get creative with the runs to make them work, and it can more often than not be a huge pain.
      Concerning the floors you can use wall packs, going up through the bottom plate on the wall and putting the supply air vent on the wall above your baseboard. Feel free to drop me an email if you have more questions.

  • @darkflux
    @darkflux 11 месяцев назад

    this was very edicational!
    the only thing i didn't understand was, on each of your trunk runs, how do you know how long to make each section of trunk? for instance, your initial trunk size was 8 x 28, but how did you know how many feet long to make it before dropping down to 8 x 20? i'm sure there is a logic there, i just missed it.

  • @MJubeily
    @MJubeily Год назад

    The duct that is drawn is the 8'' or (28'',20''.. etc) ?

  • @danmazzeo7662
    @danmazzeo7662 2 года назад +1

    Any reason why you didn't show return duct work? do you have another video on the return?
    Thanks
    Dan

    • @teachmeeverything3344
      @teachmeeverything3344  Год назад +3

      I had planned on doing one for the return air yet somehow this channel slipped through the cracks, I will work on finsihing it up since there seems to be some interest. Thanks for watching!

  • @elro2590
    @elro2590 19 дней назад

    Is it acceptable for the last branch duct to have a slightly higher velocity than the one before it? Wouldn't this cause backflow?

  • @hubercats
    @hubercats Год назад

    I’m curious as to how this design process changes if one is trying to design a two floor duct system, under the assumption that the two floors are connected (in the sense that air can flow freely between the two floors via a staircase, for example).

  • @adleysworld7227
    @adleysworld7227 Год назад

    Sorry for all the comments. The reason I asked is I jus had a unit installed in my attic, They T'd off the supply trunk and ran the Trunk perpendicular to my long side of my ranch style house int he middle. They ran long flex lines to all of the supply lines. Each trunk left and right is about 8 feet long with one said having 6 take offs and the other with 4. This is a 2.5 ton AC

  • @jamescusack2136
    @jamescusack2136 3 месяца назад

    Is friction loss the same as static pressure? My air handler has a “rated static pressure of .50inwg” and a “mad static pressure of 1.00inwg. How do the two correlate?

  • @elijahgoodman3140
    @elijahgoodman3140 Год назад

    One question though, will you have a issue moving air out of the furnace into that elbow? In commercial we used turning vanes, what say you?

    • @teachmeeverything3344
      @teachmeeverything3344  Год назад

      Turning vanes are always suggested, this video is more about duct sizing than assembly practices.

  • @idanny76
    @idanny76 2 года назад

    I have high static pressure on a new 3.5 ton heat pump. I know for sure the flex duct is the issue. I have two 12" coming out of the supply in opposite directions. I know I need an 18" for a 3.5 ton heat pump. I did a diagram layout of the duct in the attic. What would happen if I just replace the two 12" to 18"?
    Ignoring the downstairs, because everything is between the walls. The problem was even worse with an undersized return. The original and only return was a 24x18. The total static pressure on the unit was .9 W.C. I was able to drop the TESP to .66 by making the return 30x24. Since there is so much static pressure and the unit TESP is a .2 and I need an 18" for a 3.5 ton for 1400 CFM. How big does the supply plenum should be and what shape? Should the supply plenum split to 3 18" going out to each of the 3 distribution boxes? Do the other three distribution boxes also need to be larger?
    Looking at the triangle shaped supply plenum I have very little room up for a rectangle plenum. I think a 3 feet ductboard supply plenum should work. There is a foot from the Air handler to the ceiling and I think 2 feet from the attic floor to the roof. Now I am looking at two types of designs. Design #1 keeps the 18" ducts straight by having a single 18" coming out of the supply and then a distribution box splitting it to three 18". The sides would be coming out straight to the to side boxes and one going to the third box with a slight curve. Design #2 splits to three right at the supply plenum and goes to each box individually, but all three will have a slight curve. I will not be using any metal plenums..... it will be all flex duct and ductboard boxes, because of budget. I am not trying to make a perfect system, but trying to remove the restriction from the 12" undersized ducts installed and replacing the flex duct that was patched with mastic with new ones.
    Another question about the installation..... I have the flex duct running up and strapped to the roof for support. Since the supply plenum is low to the floor due to the roof..... Can the flex duct be run on the attic floor? Can you tell me which layout makes more sense and less restrictive? Thank you.
    Layouts:
    Current
    i.ibb.co/Ld9kmPM/Flex-Duct-Layout-and-Size.jpg
    Option #1
    i.ibb.co/GHyS00g/2022-07-05-0002.jpg
    Option #2
    i.ibb.co/PNN8mSB/2022-07-05-0001.jpg
    Air Handler Specs
    ibb.co/17VvF4B
    Video of attic
    ruclips.net/video/iInIN89q8GU/видео.html

    • @YoBitchChose
      @YoBitchChose Год назад

      I only read the first paragraph but 12" round flex is ALOT of SUPPLY to one grille, 18" would be ridiculous, unless you're talking about your return size?

    • @caden01691
      @caden01691 Год назад +3

      People spend a lot of hard years learning trades, nobody is going to come along and borderline design your system for free on RUclips and You clearly don't know enough to do this on your own. Call a local HVAC contractor like everyone else.

    • @teachmeeverything3344
      @teachmeeverything3344  Год назад

      @@caden01691 I 100% agree, especially being a former contractor.

  • @michaeldean8409
    @michaeldean8409 Год назад

    there are many different ( Air Duct Calculator's ) TRANE,LIMA, when you line the air volume numbers up the sizes of ducts are different WHICH ONES CORRECT

  • @kmrwoodworks
    @kmrwoodworks 2 года назад +1

    How did you perform the load calculation for this example?

    • @ktmkilljoy
      @ktmkilljoy 2 года назад

      by multiplying the standard of 400 cfm by the tonnage of the unit, then dividing that by the square footage of each room. this example shown would look like this 3 ton x 400=1200, assuming this is a 1500 square foot house 1200 cfm / 1500 is .8 then take .8 and divide by the room square footage to give you your individual room values.

  • @vqgang3575
    @vqgang3575 5 месяцев назад

    can u show a video explaining how that plenum would be set up in a attic

  • @michaelfisher7835
    @michaelfisher7835 2 года назад +4

    Why did you put the furnace, where the air has to make a turn, before the long straight main run? Wouldnt it have been better to have a straight shot without the turn?

    • @Ifeguy
      @Ifeguy 2 года назад

      Of course it would, but in real life you don't always have the option of placing the equipment in the most ideal location. Presumably you couldn't control that

    • @michaelfisher7835
      @michaelfisher7835 2 года назад

      @@Ifeguy Understood. However, if the architect did his job, he would design the home so as to make sure the HVAC was in the best area to be the most efficient. Been there, done that.

    • @Je1gonzalez
      @Je1gonzalez 2 года назад

      @@Ifeguy
      If is in the attic or basement he should have enough room, specifically if he has room to run all that duct

    • @teachmeeverything3344
      @teachmeeverything3344  Год назад +2

      Over the years I have had to put units in some terrible locations, they never leave the HVAC enough room and the designer usually draws a 3' square closet to do our work in. With that said this is a fictional home and layout, I use it for an exercise in the classes I teach. We draw the equipment in various locations.

  • @deathrowak6702
    @deathrowak6702 2 года назад

    If you have that same 3 ton system on a house 2500sq ft house with 21 heats would you match the main duct sizing to the air handler or size the duct up to 2100cfm

    • @goldenretriever6261
      @goldenretriever6261 2 года назад

      What do you mean by "21 heats"?

    • @tonyedwards9972
      @tonyedwards9972 2 года назад

      2500 Sq ft house would need a bigger unit

    • @seeqr9
      @seeqr9 2 года назад +1

      @@tonyedwards9972 almost need a second unit at that point

    • @Je1gonzalez
      @Je1gonzalez 2 года назад

      You'll need a 4 and half or 5 ton unit or two units to match the sizes of the house... (Period)

    • @teachmeeverything3344
      @teachmeeverything3344  Год назад

      A 3 ton would probably be a little light depending on what region you lived in. In Minnesota it would probably be fine. One thing about refrigeration is that it is very picky about the airflow it has. If you want it to work like it is intended it needs 350-400 CFM per ton. So a 3 ton unit would run 1050-1200 CFM. Anything more or less than that will cause the refrigeration cycle to operate incorrectly.

  • @happyj313
    @happyj313 Год назад

    What was the square footage of the house of this design

  • @frankgall6
    @frankgall6 2 года назад

    What was the blower door number?

  • @retsbew8954
    @retsbew8954 Год назад +1

    You should follow “Manual D” and fill out your friction rate loss sheet, so you can determine what friction rate to use. Otherwise, it’s just a guess. Maybe you did that, but didn’t show that part?

  • @number1pappy
    @number1pappy Год назад

    Maybe I missed it, but what is the square footage of this house?

  • @judahexodus7958
    @judahexodus7958 Год назад

    Great video but I would’ve love to see the sq-ft of the room on there.

  • @syedsaadali2945
    @syedsaadali2945 Год назад

    What's about the return air?

  • @SolarDrew
    @SolarDrew Год назад +2

    How do you know how many CFMs are needed per room? You said you'd need to know BTUs per room first, then how many CFM per BTU?

    • @teachmeeverything3344
      @teachmeeverything3344  Год назад

      The CFMs for each room are determined by the heat gain and loss for that room. This is figured up using a load calculation tool that examines things like building materials and environmental conditions to determine the heat load for the home.

  • @centrumsolutions4744
    @centrumsolutions4744 Год назад +1

    For every 300-4000 CFM drop the main duct need to be reduced.

  • @darwincabrera7668
    @darwincabrera7668 Год назад

    How did you find your cfm per room

  • @adleysworld7227
    @adleysworld7227 Год назад

    Just so I better understand. Basically the first section of trunk 1200cfm at 940 FPM could support about 12 7" Takes offs? At what point do you say it's time to reduce is it after a ton of air has been removed from the trunk? Why not run that trunk 24 feet and be done with it. Is it you just loose velocity?

  • @FoXHounDXD
    @FoXHounDXD Год назад +2

    Friction rate is not static pressure..... and you do not assign it based on duct type. You calculate it based on the total equivalent length of duct and available static pressure. Screwing this up, makes your "design" nothing but guess work.

  • @pineychristian
    @pineychristian 2 года назад +2

    Hopefully you use hard pipe duct off your branches than used flex for the last 10ft to 5ft. Flex duct was never designed to be used for the branch runs as a total run duct. It was designed for acoustics purposes to quiet down the air flow but , we see it all the time now. So people tend to think it is a normal thing ....

    • @philllsxga.7737
      @philllsxga.7737 2 года назад +1

      Correct.
      You should use as little flex as possible. But it's everywhere and we'll over 10 feet..

    • @LC-jy8mj
      @LC-jy8mj 2 года назад +3

      SMACNA ( sheet metal air conditioning contractors national association) recommends no more then 8 feet of flexible duct.

    • @pineychristian
      @pineychristian 2 года назад +2

      @@LC-jy8mj very good point. People really don't have a clue. Flex was invented in 1970 by a man in NJ it was really designed for acoustic purposes , not for ease of installation.

    • @teachmeeverything3344
      @teachmeeverything3344  Год назад +1

      I typically kept it to 10' in residential, and less than 5' in commercial. It does do a decent job quieting down ductwork as well as making some of the connection points easier. With that said just because something wasn't originally intended to be used for a purpose does not make it unacceptable for that purpose. You can adequately size flex duct runs with this in mind, even more so with the wide use of ECM motors these days.

    • @pineychristian
      @pineychristian Год назад

      @@teachmeeverything3344 you really can't "use flex more so with ECM motors these days". I've been in the hvac field for over 15 years now and seen many ecm motors fail prematurely because of being installed with too much flex duct on a system cause of the increased static pressures. Older ecm motors would " hunt " trying to find the speed they needed to operate meaning speeding up & down . Now they just fail. If you have constant torque ECM motors they will most definitely fail early on a system with too much flex duct. Flex duct flows less by design than hard pipe duct system. 6" flex duct and 6" hard pipe do not flow equally per 100ft . This is why they make Flex duct calculators now.

  • @maxrovira7315
    @maxrovira7315 Год назад

    Can you design a 2 ton system, 4 ton system, and 5 ton system please

  • @annettelopez6028
    @annettelopez6028 2 года назад

    How do you determine when to reduce the main duct size?

    • @Yiffboy
      @Yiffboy 2 года назад

      The ductulator will tell you, after you enter the ammount of CFM you need and also when you reduce,t his way you know if you go smaller on your run( more than likely and 99%?) from what i've learned.

    • @edwardjanowiak
      @edwardjanowiak 2 года назад +3

      Your supposed to reduce when your velocity drops by half, that is the guidance of ACCA Manual D

    • @pineychristian
      @pineychristian 2 года назад +1

      ☝ this is the correct answer .. I know a lot of people use the old rule of thumb of half your branches off the main but , that's not the right way either

    • @teachmeeverything3344
      @teachmeeverything3344  Год назад

      Once the velocity dips down to around 500-600 FPM in the main branch I size the duct work down. This is done to bring that velocity back up. Without the velocity (speed of the air) you wont ever deliver the conditioned air where it belongs.

  • @andyreyes6464
    @andyreyes6464 10 месяцев назад

    how do you find the length of every supply duck and plenum

    • @kathrynpe1
      @kathrynpe1 6 месяцев назад +1

      It’s in the video. You can get a calculator from your local supply store. Depending on cfm and velocity he explains it pretty accurately though if you watched it. Just trying to help

  • @MrAbYounes
    @MrAbYounes Год назад

    what about return?

  • @mikeerin5031
    @mikeerin5031 2 года назад +1

    So many of these videos are done with ducts coming through the floor. That’s not typical of homes in my part of the US.

    • @teachmeeverything3344
      @teachmeeverything3344  Год назад

      The only real difference would be the location of the ceiling registers. Typically they would be located closer to the center of the room, but still more toward the outer edges. The same types of reductions would apply with duct board or Sheetmetal. If you are using a flexible duct system it would be significantly different.

  • @adleysworld7227
    @adleysworld7227 Год назад +1

    At what point do you know you need to step down. It is every 4 takes offs? Why not run the 8x28 the entire length then? Is it you just lose velocity ?

    • @Anthony-rp3qh
      @Anthony-rp3qh Год назад

      When you dump cfm at a take off, you downsize to keep fpm and static pressure correct…basic manual D

  • @giuseppepandolfo4815
    @giuseppepandolfo4815 Год назад

    How many square feet is this house?

  • @weld3z
    @weld3z 4 месяца назад

    In my country we use 3 ton in one room

  • @JB-yq9bn
    @JB-yq9bn Год назад

    Low velocity is only an issue if you don't insulate the duck work.

  • @thomasromero8149
    @thomasromero8149 Год назад

    why .08 instead of .05 or .10? thanks.

    • @teachmeeverything3344
      @teachmeeverything3344  Год назад +1

      It's a rule of thumb that we use when we do not know the Total Equivalent Length or Available Static Pressure.

  • @danpmatz
    @danpmatz 2 месяца назад

    That a 2 ton system 28x8 is huge..
    Your unit is only going to be 14 or 17.5
    Also you should always start at the end and work your self back to the unit.
    This duct is tooo big you will have very poor air flow. Also if you dont put a Radius, fitting, at that first elbow.You are going to have significant pressure loss resulting in more lack of air flow.

  • @austinfoster6718
    @austinfoster6718 Год назад

    I don’t understand how you assumed how long you could make your duct work, I get sizing down but could I run a closed line 2000 feet without sizing down lol

  • @Seedavis397
    @Seedavis397 Год назад

    I love cold air blowing on me when I’m dropping a bomb your wrong

  • @garylarson1279
    @garylarson1279 Год назад +29

    I have a masters in HVAC technical education and this method does not reflect proper duct sizing according to Manuel D. However, if you’re going to use this method, you need to put balancing dampers on every run or you’re going to have improper air flow. Sorry but don’t believe everything you see on RUclips.

    • @user-kc3qf9sj2x
      @user-kc3qf9sj2x Год назад +9

      Yeah but if he calculated the Total effective length first it would be too confusing. Why worry about fittings and pressure loss when we can just set the slide somewhere between .08 and .1.

    • @CrazyPeiceOfPie
      @CrazyPeiceOfPie Год назад +4

      You spelled "Manuel" like the name.

    • @baron1c
      @baron1c 11 месяцев назад +6

      He had balancing dampers……..

    • @rottenheavenly6245
      @rottenheavenly6245 10 месяцев назад +21

      Starting with i have a masters in HVAC is basically saying i have totally no practical experience but I’m so smart and know better than everyone else.

    • @christophercurcio4535
      @christophercurcio4535 9 месяцев назад

      Could you possibly do a duct calculation for my house .

  • @mikeerin5031
    @mikeerin5031 2 года назад

    Pretty sure 850 CFM minus 250 CFM is 600 CFM and not 550 CFM….

  • @bhaskardas4516
    @bhaskardas4516 2 года назад

    A Better Powerful Voice is desired