modeling systems to be demolished

We want to use filters by system to handle as much documentation as possible in our model. We use this to assign supply and return ductwork to different colors and we also use it for duct size tags. This works great for new construction, but I'm running into a problem tying into existing ductwork. Changing a duct in an existing system from demolished phase "none" to "new construction" disconnects it from the system, they are no longer the right color and the tags all turn into "?"

Has anyone else come across this/found a workaround for it? In most cases it's not a big deal because the re-used portions are modeled as part of the new system and the demo'd portions can be overridden in view and tagged with text, but there are other times when it would be nice to keep things connected and organized even though they're being demo'd.

Thanks in advance.

Think "real world". Can you have ductwork connected if it's removed (demo'd)? Revit thinks in real world terms. You could add a parameter and use that as a way of filtering ductwork/fittings/accessories/flex that has been demo'd.

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Originally Posted by mattw

Think "real world". Can you have ductwork connected if it's removed (demo'd)? Revit thinks in real world terms. You could add a parameter and use that as a way of filtering ductwork/fittings/accessories/flex that has been demo'd.

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Yes, in the real world, in the building now, this ductwork is connected into a system. In the future, when the renovations take place, it will be removed. On my existing plans I would like to treat it as if it is connected, as it is in the existing building. However even in an existing view, I cannot seem to figure out a way have Revit treat it as connected, because it is scheduled for demolition in a future phase.

What I have come across myself is that when doing a project with multiple phases and existing ductwork exists in say Phase 2 & 3 but gets demolished in Phase 4, (as far as I know) there is no way to keep the ducts connected to the system during the initial phases until the phase that they are to be demoed.
Can anyone tell me of a way to accomplish this? Thanks in advance for any help offered.

Currently there is no way to have something demolished and still allow it to be connected.

The basic problem is that things like ducts and pipes are only allowed to be connected to one other thing "per connector". If I have a duct that is connected to an elbow the connection between those two are "properties" of those two elements (i.e. the duct knows it is connected to the elbow and the elbow knows it is connected to the duct).

The secondary problem is that the "temporal" concept in Revit (phasing) is primarily a "display only" concept (there are some special cases where other things are done, but primarily it is limited to display). I'm not arguing that adding temporal intelligence to these elements isn't a good thing, as there are a number of other cases that it would solve (i.e. like the ability to move something that exists in "this" phase to a different location in a "future" phase phase), but it isn't there today.

Your best bet in this case will be to filter on some parameter other than system type.

jason