Get Your Families Connected with Revit MEP 2010

Shawn C. Zirbes
CAD Technology Center, Integrated Content Solutions

Quite often at Integrated Content Solutions, we see good  looking family content pass through our office.  Some content is well constructed, some is not. One issue we commonly see relates to connectors in Revit MEP.  Most of the time, we observe a simple lack of connectors.  When connectors do exist, we see the following issues:

• Incorrect Connector Direction
• Poorly assigned systems
• Unlinked data

All of these issues cause content to be quite ineffectual in Revit MEP.  This article shows how to create and use connectors properly in Revit MEP projects.

Adding Connectors

While in the Family Editor, use one of the Connector commands from the Create tab.

These commands add explicit connector types to either of the following:

• Faces of solids in the family
• Reference planes

Once added to either a face or reference plane, if the connector is for duct or pipe, then the arrow must point in the direction of the approaching pipe or duct.

All too often, we see the connections pointing into the piece of equipment, away from the incoming duct or pipe.  It would seem that the perception is that the arrow indicates the direction of flow.  As indicated above, it is the direction from which the duct or pipe will approach.

When adding the connectors, it is recommended that faces of solids be used as the connector’s host.  However, sometimes this is not possible, for example, when placing the connector on the face of a nested family. In these circumstances, the connector needs to be hosted to a reference plane, and its position controlled with dimensions. The connector’s directional arrow will always follow the positive side of the reference plane, which is to the left side based on the direction of draw.

For more information about the reference plane +/- sides, see this article by Carl Gibson: http://revittotd.com/08/682.

Linking Connector Properties

Once connectors exist in a family, the connector’s properties should be linked to Family Parameter.  This allows end user access to the connector properties when the family is in use in a Revit MEP project.

Each connector has its own sets of properties, and depending on options selected in the connector, some options may be available for linking, or may be pre-calculated. For detailed explanations of each connector type, refer to the book “Revit 2010 Family Standards and Best Practices” also listed at the end of this article.

In the image below, a pipe connector has been added to a project, and its Flow Configuration has been set to Fixture Units to allow appropriate data input for a sanitary system.

With this configuration, the Fixture Units property should be linked to a parameter relating to sanitary fixture units.  This value can then be edited or verified by the end user of the family while in the project.  The end user does not need to know how to edit family files and how to edit connector properties to validate the connector data.

As you may be able to see, the Radius property has already been linked to a family parameter, which is why it appears deactivated in the above image.  This will allow various sizes to be generated from the same family file using family types.  If the parameter was forced to 4” and not linked to a parameter, then only the 4” version could be used.  A separate family would need to be generated for a 6” radius, and so on. This isn’t very efficient, and doesn’t lend itself to efficient family creation, nor does it lend itself to family reuse.  The same holds true with the other important properties.

For pipe and duct connectors, there is a property called Allow Slope Adjustments.  This allow the pipe to slope up or down, away from the vertical connector.  In this family, if the connector was placed such that pipe would run horizontally away from the family, the Allow Slope Adjustments property may need to be checked.  This property doesn’t necessarily need to be linked to a parameter as it simply indicates if the pipe should slope.  The user doesn’t really care to see if it is set or not.  But it is important that the value be checked if appropriate.

The Connector Description property should be filled out any time there is more than one connector of the same system in a family.  This value is the only way an end user can distinguish between two connectors in the same system type.  Without this value, the user has to play “Guess-Your-Best,” and will usually be quite frustrated when connecting multiple instances of the same family to logical Revit MEP systems.  This is another example of a parameter that does not need to be linked to a family parameter.  Instead, it should be populated with text directly in the Instance Properties dialog of the connector.  Linking this property to a parameter would only add parameters to the family unnecessarily.

Note:  Connector properties that allow parameter linking are indicated by the grey button at the end of the row where they are located.

Using Connectors in Projects

Once families containing connectors are placed in a project, the end users can create logical systems relating to the connectors. Let’s say that the example connector from the previous examples was for a sink.  The Instance Properties dialog indicated a connector System Type of Sanitary, as shown earlier. This would allow the end user to create an association to a Sanitary system within the project.

Including connectors also allows connected pipe to understand its system association, and calculate pipe properties correctly when connected to this family. Flow values, and pipe/duct/wire sizing is made possible only when connectors rich with data are present. Connectors can affect properties as simple as the automatic coloring of pipe or duct when the connector is associated with specific system types.

Conclusions

There are many benefits to including connectors and associated linked parameters in family content.  If the connectors are included, the user can benefit from data-rich building information models.  If the connectors are not correctly included, then the users may still have a piece of pretty content, but no real benefit is gained by leveraging Revit.  They could have used AutoCAD to generate the same “pretty picture.”

More Information

There are a few good resources that can be used to further your proficiency in Revit families.

- Revit 2010 Family Standards and Best Practices

- Autodesk SEEK Model Content Style Guide

- Revit MEP, Architecture, and Structure Help system and tutorials

About the Author

Shawn C. Zirbes works for CAD Technology Center, Inc. (CTC), an Autodesk Premier Solutions Provider, and consults daily at Integrated Content Solutions (ICS), an Autodesk Content Premier Member.  He has over 10 years experience as the Chief Technical Officer at CTC leading Revit implementations and furthering the use of BIM in the Minneapolis, MN area.  Currently working as a primary Revit content creation advisor, Shawn has published a book titled “Revit 2010 Family Standards and Best Practices” and consults with Autodesk SEEK to assist in the definition of Autodesk approved standards.

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