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HVAC Ducting in Autocad MEP - scheduling , printing , tag


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Hi friends, this is my first post here . I am relatively new to Autocad MEP . I recently got a job as Mechanical Engineer in an HVAC design and installation firm in a junior level, and I need to practice before joining.


I tried learning the software by my own through youtube and several of my doubts have cleared through google. But some things cannot be solved by google search and hence I have arrived here.


I have taken the autocad 2d plan of my own house from my Dad , and started practicing drawing and sizing the ducts .


I have attached the dwg file here :


Final file -



Used for Xref ground floor plan-



Used for Xref first floor plan-




These are my doubts:


1) I wish to know my duct modelling method is correct or not . I roughly estimated the flowrate required for each room , divided it by the number of diffusers that I wish to place , got the flow rate for each diffuser and assigned it to each diffuser after placing them in a room.I followed this step for all rooms . Then I started the duct drawing . I chose 2 line duct method and started from the major trunk , selected all diffusers of the same floor , got total flow rate and and duct size was obtained (medium pressure lane - velocity around 5m/s).


Is this the right method ?


2) I roughly placed the diffusers just to practice drafting. In the professional way, how to place them at particular distance from walls? I know the array function only . May be this question is dump ,but trust me I am new to Autocad thts why.:D


3) I have assigned different layers for each floor , ie blue for ground floor ducts and red for 1st floor ducts. This was done hoping that I can hide them when needed to take print out . Sorry for my stupid idea , plz tell me which is the real method to take prints in 2d for each floor separately .


4) While taking the 2d view after hiding all other floors , some of my ducts and connectors are partially visible . Its like if some portion got erased with an eraser partially. How to fix this ?


5) This one might be the stupidest of all. Does layer color come in printout ? If I choose light green , Its barely visible ? like that? or all comes in black ?


6) In the schedule table , which I plan to create consisting of duct length and duct size , I wish to give them a series-name or tag . And I need these tags to appear in the drawing on each ducts or very near it. I have no idea how to create tags for ducts. I can only see tags for air terminals and some other stuffs. I need tags for all the things in my drawing. My wish is to make the drawing easy to understand. A simple numbering over the ducts or equipment will be enough . I will sort and group them in scheduling table.


7) Some say , autocad 2d is used for hvac drafting in most companies . Why dont they use Autocad MEP ? The standard library of autocad mep doesnt match with SMACNA standards? Or is it the difficulty to create custom equipment in the library ? Or is it the fact that even if we make in 3d , the printout will be always in 2d ? All the features in autocad 2d can be done in 3d anyway right?


8) Is it possible to change the diameter of an air terminal like diffuser in our list of diffusers ? I know they have different diameters or l x b , but I wish to knw the method for modifying it. When I googled , I saw a big tough method to import a library list or something like this and copy the default list etc etc . I just need to create a new diffuser with a custom diameter with the existing design, possible ?


9) Usually , is schedule table printed along with the plan ? or is it just exported to excel and taken print ? Can the method of scheduling used to create bill of materials in excel ? Is this feature available in autocad 2d? This is a great advantage over autocad 2d?


10) The formula used in duct sizer is the same as the one in autocad mep right? duct sizer uses the simple formula - q= vA and darcy weibash equation right? the same with autocad right?


11) After I drafted , I didnt right click on my duct and choose - 'calculate duct sizes'. Since I had already sized the duct accordingly when drafting by the method described in point -1 . In the analysis tab - view by friction option was there. I was curious and tried it . But the all ducts were green in color despite I saw the duct friction loss higher than 0.7pa/m . Green was supposed to be


Out of these questions , I wish to know about the right method to take print (mentioned in doubt 3) for duct plan in each floor separately and doubt 6 is very urgent and consumed my entire day.


Please understand that I have been learning this for a week now by my own and many of my questions might be silly for you. The tutorials available in youtube is very less compared to some other software such as solidworks , catia , ansys or abaqus etc . So , each doubt takes a lot of time searching !! Please help guyz , Ill be really grateful . When I become expert in autocad , i will also be helping the new people , but I should master it first :P:D

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Long post. I'll try to come back to answer all your questions after reviewing your CAD files. Just as an FYI, especially in India and Dubai, many engineers have moved on to Revit MEP instead of AutoCAD MEP. You may want to look into this for yourself. I'd hate for you to invest into a robust software for a long time only to be forced to pick up Revit since this is where the industry is headed anyways.


More info here:




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Thankyou for ur reply. Is revit beneficial for an hvac design engineer ? People will change from hap to revit for design ? why still classic autocad is preferred in hvac? im curius

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Revit is an engineering application. AutoCAD is a drawing application. AutoCAD is the industry standard in "creating drawings" and has been for quite some time. Revit can interface with HAP loads software, and is much more tuned for the engineer. AutoCAD MEP (which is an in-house 3rd party add-on for AutoCAD) has tools for engineering, but Revit has taken the architectural and structural design industries by storm, thus naturally requiring Revit as the platform of choice - even required - for MEP engineers.


AutoCAD MEP didn't even arrive on the scene until a few years after Autodesk bought Revit in the early 2000's. Since you are using AutoCAD MEP for sizing calcs, etc, then I would suggest using Revit instead, however AutoCAD is still very relevant and you should not dismiss it either. Learning both, with a heavier emphasis on Revit, would be very beneficial to you.



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Thankyou brother . As you said , I have got in to Revit 2017 , its quite faster than autocad mep and less buggy. But I am trapped now . Its a silly thing . Ive posted it separately:




Btw, please dont waste time in the above autocad mep thing. Its okay i left it.

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