Inside the System

Defining a Type Catalog File

When defining a Type Catalog File (.txt) the first row is formatted to tell Revit the parameter name, the parameter type, and the units... such as:

<paramname>##<paramtype>##<paramunits>

However, it is not always obvious what to use for the type and the units.

Instead of trying to remember where this is documented, you can export the family types, and the file will be created for you:

From within Family Editor, click:  Application Menu > Export > Family Types

The following definition will generate output similar to the following:

,SomeText##OTHER##,SomeTemp##HVAC_TEMPERATURE##FAHRENHEIT,
SomeNum##OTHER##,SomeDensity##HVAC_DENSITY##POUNDS_MASS_PER_CUBIC_FOOT

Using the Spot Elevation Tool to Tag Bottom and Top of Pipe in Revit

You can use the spot elevation tool to tag the Top Of Pipe (TOP) and Bottom Of Pipe (BOP).  With a little configuration of the types, you can annotate the top and bottom of the pipe elevations with an appropriate prefix.

 

Adding Dimensions to Pipes in 3D Views in Revit

You can add dimensions to pipes in 3D views.  By creating reference planes for your pipe annotations and adjusting your workplane, you can place the dimension lines adjacent to the pipes.  By constraining the reference planes to the pipes, you can keep the dimensions aligned with the pipes, even if the pipes move.

  

Routing Conduit up to 6" in AutoCAD MEP

The conduit catalogs in AutoCAD MEP include sizes up to 6" for Aluminum and Galvanized conduit, however, the default part routing preferences only allow routing of sizes up to 4".  This is because the transition fitting in the preference is only avaialble up to 4", and therefore, restricts the available sizes.

If you remove the transition from the preference (or modify the transition to include sizes up to 6") you can then route 6" conduit.  

The embeded video demonstrates how to modify the preference to remove the transition.  Note that it is likely you will need to save/close/reopen the file after modifying the preference.

  

Default Load Values

I was recently asked where the default values for lighting loads and power loads come from.  These default values are found on Spaces when you inspect them using the Heating and Cooling Loads tool, and when you directly inspect the Space in the model. 

The short answer is that they come from the settings in Manage > MEP Settings > Building/Space Type Settings.

By way of an example, if the Space has its Space Type set to <Building>:

The Building Type is Specified in H/C loads dialog (or in Manage > Project Information > Energy Settings)

The Building Type has a set of properties in the Building/Space Type Settings window.

These settings are referenced when you are running a load, or checking things such as the Electrical Loads settings on a Space.

To help visualize, this eye chart may be helpful.

Windows Vista Compatability

Beginning January 1, 2012, Autodesk will have formally ceased support of the Microsoft Windows Vista Operating System for all new (and upgraded versions) of its products and services released in 2012.

Currently shipping versions and previous versions of our software (delivered prior to January 1, 2012) will continue to be supported on this operating system.

Windows XP & 7 are still supported.  See the following link for more 

http://autode.sk/xY3PHO

Constraining a Family to Disallow 'Invalid' Connector Sizes

Recently, I was asked how one might constrain a connector width in an instance parameter to be less than the width of solid it is hosted on.  In the specific case, there are two solids, one representing the main body of the equipment, and the duct 'collar' on which the connector is hosted.  The duct size must match the collar, and the collar must stay smaller than the equipment.

The formula below to control the collar size works just fine... however, when you select the family instance in the project, you can use the blue numerical control to set the connector width to something larger than the geometry... as you can see from the formulae, there is are no constraints on the actual duct connector sizes.

The problem is one of validation, not constraints/dimensions.  As you can see in the revised parameters below, there are a couple of checks to make sure the duct size stays smaller than the section size.  If the duct is modified to be bigger than the body, we force the collar length to 0, which Revit will not allow, and a error to the user will force them to undo the invalid setting.

How would you approach this problem?

BIM Café – Architect Driven Changes

A new 4 part video series has launched introducing the value of BIM for MEP and structural engineers. Watch episode one of four today!  In this episode of “Cafe BIM – Architect Driven Changes” watch what happens when Greg’s hospital project runs into a mechanical design challenge.

 

AU Virtual 2011

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Plan now to attend this worldwide virtual event November 29–30, 2011. More than 150 more classes go live on November 29.

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After the event, AU Virtual classes will continue to be available on the AU website.

AU Virtual Preview Classes Are Available Now

More than 45 previews classes are now available on AU Virtual, including technical and certification preparation classes—especially helpful if you plan to take a free certification exam at AU in Las Vegas.

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What does the 'Use Load Credits' option in Heating / Cooling Loads do?

From the help file, it states:  accounts for heating or cooling “credit” loads that take the form of negative loads. For example, heat that leaves a zone through a partition into another zone can be a negative load/credit.

To exapnd on this, look at a couple of fundamental examples.

In the case of a heating load, it is common to not include internal gains, such as people, power, and lights.  The basic assumption being that these things may not actually be on or in the space to provide the gain. 

However, if you want to consider the internal gains in a heating calculation, the ‘Use Load Credits’ option will do this for you.

For example, looking at a single zone, in the Use Load Credits case, you see the heating load is less due to the credits from the internal gains:

Click to enlarge image.

Taking a look at a cooling load case, in the image below, the two zones have different set points.  Zone 1 is kept cooler; therefore, heat will “flow” from Zone 2 to Zone 1 (indicated by arrow 1).  In other words, there is a load on Zone 2 due to Zone 1.  Conversely, this means there is an internal loss from Zone 2 to Zone 1.  However, if you don’t ‘Use Load Credits’ you don’t see this in your cooling load calculation.  Arrow 2 on the tables below show the partition load, without the credit in Zone 2.  Using load credits allows the reduction of the load in Zone 2, as shown by arrow 3.

Click to enlarge image.