topic Re: My sanitary pipes changed to vent in Revit MEP Forum

My sanitary pipes changed to vent

Anonymous — Tue, 01 May 2018 20:23:16 GMT

In a section of the building I'm working in some most of the sanitary piping changed to vent (red=sanitary green=vent) and i do not have the option to change it back to sanitary piping. I presume it has to do with different system classifications, although it was never a problem before. Just about everything you can see in this screenshot was, and was supposed to be, red(sanitary). This happened after I synchronized, I saw it change as the sync finished.

Re: My sanitary pipes changed to vent

RobDraw — Tue, 01 May 2018 20:43:22 GMT

This can happen when connecting vent piping to sanitary. I don't do this kind of piping but the problem is usually a fitting family with improper connector settings.

Re: My sanitary pipes changed to vent

Anonymous — Tue, 01 May 2018 20:47:06 GMT

What would make the connection setting improper? And how would I change it if it is wrong? By the way, I've never had this problem before when connecting vent to sanitary, at least not something to this scale.

Re: My sanitary pipes changed to vent

RobDraw — Tue, 01 May 2018 20:53:42 GMT

@Anonymouswrote:
What would make the connection setting improper? And how would I change it if it is wrong? By the way, I've never had this problem before when connecting vent to sanitary, at least not something to this scale.

I said it was the connector settings and I was referring to the ones found in the fitting families. If not done properly, instead of splitting the systems, it carries one of them through the fitting.

Hopefully, someone more familiar with this will come along and share some more specific details.

Re: My sanitary pipes changed to vent

fabiosato — Thu, 03 May 2018 03:08:54 GMT

Hello,

After you connect vent to sanitary system, if you edit any piping sytem, both will change to same, when I do it, I create the sanitary piping, then the vent piping and connect then from vent to sanitary.

Re: My sanitary pipes changed to vent

debimmanager — Thu, 03 May 2018 12:54:51 GMT

Guru @RobDraw, give a solution and do not confront people who seek help. @fabiosato is right, the best option is to connect the vent to sanitary, and if you sanitary piping change to vent, disconnect a vent segment and try to connect again to sanitary and the sanitary system come back, after that, try with the vent to sanitary.

Re: My sanitary pipes changed to vent

RobDraw — Thu, 03 May 2018 13:01:36 GMT

@debimmanagerwrote:
Guru @RobDraw, give a solution and do not confront people who seek help.

What? Please show me how I confronted the OP. Oh, I'm sorry, you're just bent because I pointed out that you misunderstood that other post. Get over it.

Re: My sanitary pipes changed to vent

debimmanager — Thu, 03 May 2018 13:18:07 GMT

@RobDraw blessings my friend. Forget it.

Re: My sanitary pipes changed to vent

pieterdewaal — Tue, 22 Sep 2020 12:15:32 GMT

This is an old topic, but it wasn't resolved. For future reference to anyone:

Create a pipe coupling family (you can use the standard pipe union family as a basis). Change the one connector's classification sanitary and the other to vent. This allows you to split the system somewhere along the pipe.

Force the length to be around 5-10mm. Now, connect the drainage part to the sanitary connector and the vent to the ventilation side. The system "decoupler" will now be on both systems, but the piping only on the correct system.

SanitaryVent

Re: My sanitary pipes changed to vent

bcpratt70 — Thu, 28 Apr 2022 16:14:15 GMT

Sounds like a good concept and I tried it, but it did not work for me. My piping and systems were already created and I tried adding the described coupling in after the fact. I verified coupling orientation, but the piping seems to be "stuck" to the existing sanitary system and I do not have the option to change system System Type to vent after coupling inserted - the drop down list is populated only with sanitary type systems.

Re: My sanitary pipes changed to vent

RobDraw — Thu, 28 Apr 2022 16:21:00 GMT

Try selecting only the pipes using the drop down just below the type selector.

If that doesn't work, you will have to try removing the pipe from the system making it unassigned and then connect it to the correct system type.

Re: My sanitary pipes changed to vent

bcpratt70 — Thu, 28 Apr 2022 16:50:45 GMT

Thanks for the quick response. To test I did as you suggest, but the coupling does not act as a "disconnect" and the all of the connected pipe changes. No doubt this is because it is still part of the logical system even though it appears to have a coupler. I tried disconnecting pipes by moving them apart, but this doesn't work either. How can I remove pipe from a system?

I initially did as suggested and started with the OOTB connector. Just now I created a family from scratch and it works as described above. Now I just need to figure out how to get my new connector to inherit the size of the pipe I'm inserting it into (not a ton of experience with families and parameters...)

Re: My sanitary pipes changed to vent

iainsavage — Fri, 29 Apr 2022 06:51:41 GMT

In theory, you should be able to have different systems connected together as long as there is a fitting (standard ootb fitting between them) but there is a method which has to be used which is that you do not try to draw a vent pipe into or away from a sanitary pipe using auto connect to create the branch.

You have to create the branch on the sanitary pipe first and then draw the vent pipe from space going toward the branch, not from the fitting connector outwards.

Pulling pipes apart by a distance will usually allow you to change their system type to anything. If you only pull them slightly apart they sometimes remain connected and you can then only select systems of the same classification.

If you need to remove the system altogether, pull the pipes apart, tab-select until the system (not components) is highlighted (usually 4 tabs) then on the ribbon use the divide system tool. It will say that it is going to divide the system into two networks, do that.
Then for the part of the system that you want to alter classification tab-select again to select the system (not the components) and delete the system. Then draw a vent pipe connecting into that system and the whole system should become vent. Delete the temporary pipe that you created to reset the system classification.

Then, if you still want your vent pipes to be connected to the sanitary system, pull the pipe end into the already existing branch on the sanitary system.

Re: My sanitary pipes changed to vent

iainsavage — Fri, 29 Apr 2022 06:55:18 GMT

That was the theory. In practice, as others have reported, it often goes awry when the model is synced.

I’ve had similar problems with domestic hot water returns branched into the domestic hot water flow and now I generally leave the two systems disconnected from one another rather than risking having to spend hours trying to find the one connection which has created the problem.

Re: My sanitary pipes changed to vent

bcpratt70 — Mon, 02 May 2022 11:52:42 GMT

Thanks for the responses on how to work-around this issue. I didn't read the suggestion about dividing systems until after I did something different. I'll keep that in mind because it sounds a little less of a pain than what I wound up doing: disconnecting what I want to be vent, cutting that to a blank model, changing it to vent and then copy/pasting it back to the original model.

Re: My sanitary pipes changed to vent

tyronethompson — Mon, 02 May 2022 15:30:16 GMT

I've found this to be the quickest way to find the "break" in the system. It's easier to find the element that's allowing the cross-over if you can see the networks by system, it's normally one of the DWV fittings in my experience. Hopefully, it divides into 2-3 systems and not 15 🙂

Re: My sanitary pipes changed to vent

HVAC-Novice — Tue, 27 May 2025 16:24:05 GMT

I know, old thread. I just stumbled across this. I found making the "transition" to be "cap" works better.

I found the following workflow helpful:

extend vertical sanitary to the pint I want to transition
cap it with regular cap
swap out the cap for this "cap" fitting.
draw the vent pipe from the fitting (it often will be sanitary at first and can't be changed to vent yet)
disconnect that vent pipe (currently still classified as sanitary)
change classification to vent (this is why we disconnect first)
reconnect to the coupling

When the attached family is "transition", step 7 causes the transition to disappear and the entire pipe becomes vent (even below my planned transition point)

for some reason the fitting doesn't use the color of vent or sanitary.

I have the feeling, Revit is a bit tricky here and inconsistent. I recommend to play around a bit and put a tag that shows FU on the pipe to ensure FU calculation still works.

Re: My sanitary pipes changed to vent

iainsavage — Tue, 27 May 2025 16:53:07 GMT

"for some reason the fitting doesn't use the colour of vent or sanitary"

If you're using system graphic overrides rather than filters and the fitting is associated to both systems it will revert to the default colour in Object Styles.

The other possibility is that if you are using a nested components in the family they don't adopt the system settings at all and you have to use view filters to apply colour etc.

Re: My sanitary pipes changed to vent

HVAC-Novice — Tue, 27 May 2025 18:49:11 GMT

That was just what I noticed. I'm fine with that fitting looking different.

But I just noticed what I said above doesn't work. it works initially and the sanitary pipe shows the fixture units. but ones I connect it to other pipes with Wye/Tee, the FU calculation fails. Either my system then shows 0 FU, or just the ones that don't come from branches that have that fitting for the vent. I couldn't really resolve it and for now i just cap the sanitary pipe with a regular cap and put a fake vent pipe in the same location so it just "looks like it is connected"

So yes, this is even more tricky since it can work partially and you may not notice if you just miss that one or two FU.

Re: My sanitary pipes changed to vent

iainsavage — Wed, 28 May 2025 18:43:00 GMT

I didn't read all of the history in this thread but I'm sure there's another similar post where the solution was to make the coupling Mechanical Equipment or Plumbing Equipment containing the two different System connectors and passing values between them using parameters and a formula.

I don't know though if that actually works.