Groups instead of Custom Families
This spot is going to be geared towards Plumbing BIM. I hope it applies to other disciplines, but that is a determination you will have to make.
A few months ago I sat through a webinar about how to use Revit/BIM in plumbing design and engineering. I consider myself an advanced, not quite expert, user of Revit so I am always looking for other learning opportunities. Anyways, the webinar did not go well. The presenter showed us a custom sink family he created with the P-trap, sewer line to wall, vent connection and hot and cold water connections. He then placed his family in the project, clicked on his vent connection and tried to connect it to the vent main in the ceiling… it didn’t connect and the presenter then spent the last 45 minutes of the one hour webinar trying to get the family connected to the Vent main. The problem was not the presenter or his process, the issue was strictly with his custom family, it wasn’t reading the pipe types correctly and therefore could not automatically place the required fittings. It is my contention, and the reason for this blog spot that custom families are not necessary; Revit provides everything to hook up the fixtures and plumbing equipment correctly, to speed up the process and gain consistency and ease of use I recommend creating groups. Don’t get me wrong in some instances custom families are necessary and needed, but there is no need to reinvent the wheel so to speak.
I do not know the official Autodesk definition of groups but my definition is; it’s a bunch of related and connected families selected to use as a single family while retaining the attributes of the individual families. That’s right, I said it. Hopefully after going through the step by step you will read that definition again and say, “Oh, now I see what he means.” If not, I will try to change my definition. Okay, let’s get started.
I am going to use a lavatory for my example because it has four systems (cold water, hot water, sanitary sewer and sanitary vent). This should give a good idea on how to create a group. Also before I get started there will be some items mentioned in here that will be discussed in more detail in near future blogs… mainly systems, how to use systems to your advantage, and shared parameters, how to get the information from the model to your schedules, calcs, QTO, etc.
First load your family into the project (You can just open the family, I just prefer to do everything within a project… no reason just a personal preference). The select the family and click “Edit Family” in the ribbon or via Right click.
This is a good example because I do have to customize things a bit. You can see in this shot, the sink shows the drain connection on the wall rather than on the sink. For me, this is not the level of detail I show. I do section views and isometrics and I show how it is connected from the sink to the wall. So we have to move the sewer connection.
So I click on “Pipe Connector”, select my plane (typically selecting “face” will do well). I select where I want to place the pipe connector.
Now we have to set the parameters of the connector. This is what it looks like now.
Then you have to do this in order.
- Change the System Type from Hydronic Supply to Sanitary (or whatever system you are creating)
- Change the Flow Configuration to “Fixture Units”.
- Now the “Fixture Units” row is editable and should have 0.00000 for the value.
- Click on the little box on the far right side.
- That will open the “Associate Family Parameter” window
- Select the parameter to associate that value, in this case “WFU”
- Set the flow direction.
- The flow direction is very important. As you connect fixtures to the pipes, Revit will automatically calculate the fixture units, flow, etc. The flow direction basically tells Revit the order in which to add the items.
- Loss method (I usually leave this as Not Defined but that is only because I don’t use that feature in my designs)
- Change the radius.
- Again you can either open the “Associate Family Parameter” window and associate it with a parameter or enter your own value.
- On a lavatory, I enter my own value because we always spec a minimum 2” sanitary sewer pipe
Then repeat those steps for the cold water and hot water. If required for your level of detail. We typically do not show the domestic water from the wall to the sink. We figure when completed delete the old connections. Now it should look like this.
Add and modify the parameters to the family based on your company’s standards and policies (in about two weeks I will post some ideas and procedures I use for parameters)
Load the family into your project, select “Overwrite the existing version and its parameter values”
Okay now we are done with the prep work, we can begin creating our group. I show everything to the wall. For example, for the domestic water I draw a pipe to the center of a standard 6” wall and then an elbow going up. For the sewer I show a combination Wye with 8th bend, flow direction down for the sewer and the up is for the vent. (This is part one of the definition: it’s a bunch of related and connected families)
- A word of warning about the Vent and Sewer connection. Once you connect the vent to the combination wye it all becomes one system, either the vent system or the sanitary system and the automatic fixture unit calculations are messed up
- You could create a custom fitting and mess with the flow direction etc. But again, why reinvent the wheel?
- What I do is connect a short pipe to the top of the fitting and then add an endcap, and then I mirror the endcap and place the 2nd one on top the first.
- What this does is tells the sanitary system there is nothing further downstream so figure the calculations from this point. It also provides a POC for the vent system.
Here is the finished product
Once you have all the pipes connected as you want and have verified the connections
Go to either a top down view or section view and select everything you just connected, Go to Annotate in the ribbon, then Detail Group, then Create Group
Give it a name that makes sense and is within your company’s standards then select “OK”.
Now a box will form around everything. You also need to go to the bottom of your Project Browser to the Groups section.
- Right Click on the group you just created
- Go down to “Save Group”
- Save the group in the folder designated. I created a “Plumbing Groups” folder and then sub folders based on fixture type.
- The default settings are good for the save
- Click “Save”
You now have a group that can be used in future projects. To load into other projects just:
- Click “Insert” on the ribbon
- Click “Load as Group”
- Navigate to your group folder
- Select the item and click “Open”
- It is now loaded into the Groups section of your project browser and can be dragged and dropped into the project.
You can move, copy, mirror, rotate, etc the group and it will behave as a single family. (This is part two of my definition: selected to use as a single family).
At this point the fixture will show up in your schedules, if you automatically calculate fixture units, they will be added into the calculations, but you cannot do anything with it. You cannot connect it to the pipe mains.
All you have to do is select the group and then click the “Ungroup” button in the ribbon.
Now each part of the group becomes an individual item again. (The last part of the definition: while retaining the attributes of the individual families). Now you can click on the Cold water elbow, select the “Connect Into” button on the ribbon, select the cold water main and viola your lav is connected to the CW system, the fixture units are automatically calculated, if you set up your systems and filters correctly the pipe color and linetype will all show up correctly, your schedules are automatically filled in and you are ready to move to the next system.
In summary, my philosophy is, if it doesn’t have to be custom ordered then a custom family is not necessary. A company could easily spend too much time and way too much money creating custom families, when 90% of the time it’s not necessary. For a few reasons: one, very few projects are at the level of detail where a family has to look exactly like the real family; two, for the time being we are still in a 2D world, meaning we create these great models and then turn in printed 2D construction drawings; three, chances are the manufacturer is busy creating their own families as I am writing this. In our company, at the start of a project an employee spent over 40 hours creating some air handlers, before the 60% submittal we got a DVD from the manufacturer with all their equipment in the .rfa format. There is a time and place for custom families, but that has to be based on the family, the project and the project goals. Thank you for reading and I hope you found the information useful. Any comments or questions you can send me a message through Club Revit or my LinkedIn page (Ted Sabinas).