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AutoCAD MEP Comparison: Inserting Fittings

Thursday, June 17th, 2010

Last week, I talked about a difference between Design Master Electrical and Revit MEP. The idea for the article was to demonstrate the difference between the two programs using a specific example. In addition to being asked for comparisons to Revit MEP, we also get asked for comparisons to AutoCAD MEP. This time, we’ll look at a difference between Design Master HVAC and AutoCAD MEP.

The specific example we will examine this time is, “How do you insert an elbow between a 40″ x 20″ duct and a 40″ x 46″ duct?”

Here’s what you need to do in AutoCAD MEP. Note that the transition elbow was not inserted automatically. AutoCAD MEP apparently has multiple types of elbows, including a “rectangular metered transition elbow”, a “reducing elbow”, and whatever elbow fitting was inserted automatically that caused the initial problem. Getting this fitting to draft correctly involves you choosing which fitting to use.

Here’s what you need to do in Design Master HVAC:

  1. Insert the centerline of the 40″ x 20″ duct (use the DM HVAC->Duct Centerlines->Insert Duct command). Set the duct information correctly–shape to rectangular, width to 40″, depth to 20″, airflow type to return.
  2. Insert the centerline of the 40″ x 46″ duct (you will be prompted to insert this duct after the first is inserted). In this specific instance, this duct should be vertical, so press “V” to insert a vertical duct instead of specifying the end point. All of the duct attributes will be copied from the duct you connected this one to.
  3. Query the second duct you inserted (use the DM HVAC->Duct Centerlines->Query Duct command) and set the depth to 46″.
  4. Draw the 2D or 3D representation of the ductwork (use the “DM HVAC->2D Drafting->Draw Double-Line (Wind0w)” or “DM HVAC->Sections and 3D Drafting->Draw 3D Ductwork” commands). A transition elbow will be inserted automatically.

In AutoCAD MEP (and Revit MEP), fittings are handled as items separate from ducts. A reducing elbow is different from a normal elbow. You are required to pay attention to this and make sure you choose the right type of elbow for the specific situation you are in.

In Design Master HVAC, fittings are a side-effect of where you place ducts. If a fitting is needed, it is automatically inserted. If the duct changes shape or size, the appropriate fitting is chosen and inserted automatically, without requiring you to select it. We have one fitting, a square elbow, that works in all instances, rather than the three (or more) that AutoCAD MEP has.

To learn more about Design Master HVAC, contact us for a free demonstration and 30-day trial. Like I said about Revit MEP, the only way to make an educated decision about Design Master HVAC and AutoCAD MEP is to try them both and see which works best for you.