Hello, Everyone,
Today I will show you how to draw Round Radius Elbows In Ducts, using LISP.
Download the required Lisp from here then add it to Autocad Lisps and run the Lisp by typing "ee" in the command bar then do as shown below:
1-After running the lisp it will ask you to:
-pick the outer side of the main duct.
-pick the inner side of the main duct.
-pick the inner side of the branch duct.
-pick the outer side of the branch duct.
2-Pick lines as shown in screenshot below:
3-After choosing lines as described above the lisp will draw the elbow for you!
For more illustrations see the video below:
Download the Lisp from here
Note: you can use this lisp to draw other duct fittings like duct tee, duct branch with 45°take-off and duct branches with two elbows in the same direction for more details see the below link
-To download more Lisps for HVAC Design drawings go to:
-If you get any error when extracting the compressed file download the latest winrar Version
Great tutorial—using AutoLISP to automate elbow creation really simplifies what can otherwise be a repetitive drafting task. The step-by-step selection of duct boundaries is especially helpful for accuracy. It also highlights how proper elbow geometry supports smoother airflow and reduced losses in real systems. Integrating such precision becomes even more relevant when evaluating system efficiency alongside solutions like Kinghome Heat Pump in modern HVAC design.
ReplyDeleteInsightful article! It clearly explains how to properly draw elbows in HVAC ducts, which is crucial for airflow efficiency and system performance. I recently had services from Islandaire HVAC, and this post highlighted the technical details that really matter when installing or inspecting ductwork. It’s a useful guide for anyone in the field.
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