I fully expect that at some point I'll need to break this page up into multiple pages each of them specific to areas of the application, but while the list is short I'm keeping it on one page.


Q: Does everyone working on a project need to be on the same build of Revit (even across disciplines?)?
A: As usual, it depends. Everyone working on a project should be on the same version of Revit. Additionally it is recommended that everyone working within a single central file be on the same build of Revit (i.e. have the same update releases / hot fixes / etc. installed). If the architect and engineers are simply sharing linked files, then it is not required that they be on the same build (version, yes, as one won't be able to open the others if they are not on the same version). Since a linked Revit model is not opened for write, it is impossible to change the link. If the architects and engineers are working on different builds, and the only sharing that is taking place is via links then it technically doesn't matter. There is, of course, a caveat, in that they may not see the same things if they are working on two different builds, but that's quite possibly the case if they aren't working on the same exact view settings anyway, so isn't as big of an issue :-)
Q: How do I turn off calculations in Revit MEP?
A: You can't. If you could it would help much less than you think. This deserves a larger discussion, but the short answer is simply that you can't turn them off.
Q: How do I "Save as" a Revit project to an older version of Revit?
A: You can't. So far every new version of Revit has been a file format change from the last one, and no version of Revit has provided the ability to save as an older version. Sorry. The same applies to families as well. If you create a family in 2010 you can't "save as" a 2009 family. It is recommended that you maintain separate family libraries if you are using different versions of Revit MEP on different projects.
Q: How do I get Revit to use a different elbow that the one that it is currently using?
A: You have to tell it that you want it to use a different elbow. First make sure that the elbow that you want to use is loaded into the project that you want to use it in. Next click Duct (or Pipe, depending on what your elbow is for), and click Properties. In the properties dialog click Edit / New (upper right portion of the dialog) and then in the Types dialog change the fittings that you are using. This won't update the existing ducts (or pipes), but any new ducts (or pipes) drawn with that type will use these new fittings.

Linked Files

Q: What are the best practices for setting up a new project in Revit MEP?
A: Too much to answer as a "one liner". See this page for a description.
Q: How can I connect to things like lighting fixtures and plumbing fixtures in a linked file?
A: You can't. Currently the only options are for you to 1) Not connect to them, 2) Copy / Paste them from the linked model into your model and manually coordinate them, or 3) Place "dummy" connectors on them and connect to the dummy connectors that represent them.

Sub Disciplines

Q: What does the Sub-Discipline property on a view do?
A: It doesn't do anything but change where the view shows up in the Project Browser. It has no affect on anything that is actually displayed in the view.
Q: How can I add a new Sub-Discipline to the list of Sub-Disciplines in view properties?
A: Open up the view properties of the view that you want to add a new sub-discipline to. Highlight the value that is in the Sub-Discipline feild and type in a new value. That's all you need to do. After you click OK, the new item will show up in the Project Browser (assuming that you are still sorting as it was set up in the default template). The Sub-Discipline value is simply a project parameter implemented in the default Revit MEP templates.


Q: When I try to draw pipe only whole number show up in the size drop list. I've checked mechanical settings and it says that I have a number of non-whole number pipes defined. Why can't I use them?
A: Settings -> Project Units. Change the discipline to Piping. Pick the "Pipe Size" unit. Change the rounding to 'To the nearest 1/8"'.

Rooms / Spaces

Q: I've heard that I can use walls in a linked file as the boundaries for spaces, but I can't get it to work. What did I do wrong?
A: Select the linked file and go to Properties -> Type Properties and turn on the check box for Room Bounding.
Q: How do I get all of my space names to match the room names in the linked file?
A: There is a plug-in on the subscription page for this. The plug-in works for both 2009, and 2010. If you had the plug-in installed for 2009, you will need to re-install it after installing 2010 for it to "know" about your 2010 installation.


Q: Can I add more demand factors to the list. The current list doesn't include everything I want?
A: Currently it is not possible to add to the list of demand factors.
Q: How does Revit MEP Calculate wire length on a circuit?
A: As described on this page
Q: What does the "Circuit Description" setting in Electrical Settings do?
A: Help is wrong. It doesn't do what help says. What it does do is control the formatting of the Circuit Description parameter that is on a wire. This was implemented to solve a very specific user request to be able to tag the # of poles and rating of a breaker on a home run (rather than the circuit numbers).
Q: How can I tag the 2nd connector on a device?
A: Simple answer... You can't right now. There are some hacks like putting in a 2nd device in the same place and drawing a "very short" wire that will work, but there ins't really a way to do this today.
Q: Why aren't "gaps" showing when my wires cross?
A: Could be any number of things... The obvious ones are: What is the view discipline set to? It should be "Electrical". Do you have "thin lines" turned on? If so, turn it off because wire gaps won't work with it on. What is the Model Graphics Style of the view? For gaps to work it has to be Hidden Line. In Electrical Settings -> Wiring there is a setting for Gap of Wire Crossing. What is it set to? It should be set to something between 1/4" and 1/64" if you want to see a wire gap.


Q: How do I create families in Revit MEP?
A: There is a Revit MEP Families guide posted at http://usa.autodesk.com/adsk/servlet/index?id=13092938&siteID=123112&linkID=9243140 that tells you how to create some of the more common revit MEP families like fittings, accessories, equipment and devices. It also covers basics of things like lookuptables. If you haven't read it please give it a try.
Q: How do I know which connector is the primary connector?
A: The concept of primary connectors deserves a bigger discussion, but the primary one is the one drawn with an "X" in the middle.
Q: What do the different Flow Configurations on connectors do?
A: For duct and pipe connectors there are 3 possible "flow configurations" on the connectors (technically there is a 4th one for pipe, but we'll ignore that for now), they are Preset, Calculated, and System. When or why would you use the different ones? Preset would be used when you want to specify the flow value directly on the connector itself (this is normally done by mapping the flow value to one of the family parameters). Whatever you set as the value will be the value and the application won't change it. That one is simple enough. Calculated means that the connector will "inherit" the flow from whatever duct / pipe / fitting you connect this thing to. If the duct you connect it to has a flow of 5000 CFM, then the value on this connector will be 5000 CFM. In this case it doesn't matter what the flow of the "system" is, it simply looks at the connected element and sets its flow to match. Setting the "flow configuration" to System, means that there is another parameter enabled called Flow Factor. The Flow Factor parameter allows the user to specify a percentage of the System flow that will be assigned to this connector. The "example" case for this is two parallel pumps, where each of the pumps carry 50% of the flow of the system. 
Have a question that you would like to see added to the FAQ? Please send an email to RevitMEP@Comcast.net.