Inside the System

Upgrade Your Project from 2012 and Get Loopy!

Revit 2013 introduces a new Arrow Style for Loops, though it may not be immediately obvious how to use it in an upgraded project.

1. On the Manage tab > Settings panel > Additional Settings > select Arrowheads
2. Select any of the types, and click Duplicate...
3. Name the duplicate Loop, or something suitable, and then click OK twice.
4. Now, select a tag with a leader in a view (such as the Pipe Size Tag).
5. On the Properties Palette, click Edit Type.
6. Click Duplicate...
7. Name the new type 'Pipe Size Tag with Loop', and click OK.
8. Set the Leader Arrowhead to Loop (or whatever you named it in step 3.)
9. Click OK.

Your pipe tag now has a loop leader.

How to Identify Uncircuited Connections

You can quickly find uncircuited elements using System Browser.  Under the Unassigned > Electrical section, you can find connections that are not circuited.

Under the Electrical section, you can find connections that are circuited, but not connected to a panel... these will have the circuit indication of <unnamed>.

Connections that are circuited will show the circuit number.

You can select any connection in System Browser, right click, and select Show to 'zoom' to the associated object in the model.

If you want to visually identify this in the model canvas as you are working more dynamically, you can use View Filters to color these conditions.

On the ribbon View tab, Graphics panel, click Filters.

I've defined three filters for three conditions as shown below.

Uncircuited

Circuited

No Panel

With these filters defined, you can now apply them to a view as shown below.

The resulting view will look something like that shown below.

The System Browser can reliably be used to find uncircuited connections, however, since only the primary electrical connector in the familly is tracked by the Panel / Circuit properties of the instance, the View Filter may not accurately show the circuited color state of all connectors for elements with more than one connector. 

Happy circuiting!

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.

  

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.

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?

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.

ASHRAE Viewer Available in Labs

There is a simple tool available on Labs to help you select duct fitting tables, and to help you 'see' the information the tables are based on.  Download here:  http://labs.autodesk.com/utilities/AshraeViewer/

 

 
 

Documenting Multi-Section Panels

For electrical users, a somewhat common inquiry is how to document multi-section panels.  Please watch the video below for a method that lets you utilize circuit numbers over 42, and clearly document that the panel represents a multi-section installation.

Please provide any comments to let your fellow users know if this method is suitable... and if not, cite any applicable regulatory requirements that make such a method invalid.

Relationship Between System Inspector and System Schedules

Did you know?  The Static Pressure reported in a Duct System Schedule reports the same value that the System Inspector reports as the Static Pressure at the duct section closest to the inlet to that system.  This value is the sum of all the losses along the critical path for that system, including losses in duct segments, fittings, air terminals, and other accessories.

The Pressure Loss value you see in the inspector is the sum of the losses only in that section (which generally includes ducts and fittings of the same flow and size).