Piping transitions between two piping systems

[RonMaurer]

Hi,

I have been been fighting where my pipe transitions from one piping system to another (i.e. a sanitary rise transitioning to a vent or a sanitary pipe transitioning to a below grade system (for line type control) ). Leaving a small gap seems like a pretty feeble solution. I tried to make a transition fitting that had vent on one end and sanitary on the other, but that didn't work, How is everyone else handling this situation?

TIA

[ceyhunyuzuak]

I have no solution for this and I don't believe there is any. but there is a workaround that I have been using for hydronic systems. The main idea is:

-Go into transition family

-unlink connection elements (assuming there is a link)

-most importantly: save it as a "mechanical equipment" with different name

-load it into project and place it manually.

-don't use "Break Into" function

you should play around with the connector elements to see how you should set Flow Configuration,  Flow Direction and System Classification.

if you can upload your .rvt file I believe I can find correct settings (I don't design plumbing, HVACR only) but again, saving it as a mechanical equipment is the main idea.

because that's the only family type (that I could yet discovered) that allows multiple system with even different classification.

[hmunsell · Accepted solution]

give this a try.... 

https://autode.sk/3eAVvJB

In my models I am using mostly Standard, out of the box, Revit families. if you are using Vendor or Supplier provided families, they may have things hard coded into them that would prevent this from functioning. 

[RonMaurer]

The video has very helpful. It was pretty much what I was already doing, but it helped validate that I was approaching the problem the right way.

Thanks

[pieterdewaal]

I use a custom pipe fitting, a modified version of the OOTB union fitting, and edit both sides to be bidirectional flow, calculated.

Then I set the one end for example "Vent" and the other "Sanitary". This allows me to connect the vent piping to the drainage without systems overwriting each other.

Pipes cannot have two different system types applied, so splitting systems via pipe fittings is the way to go.

[iainsavage]

Was this post edited? I seem to recall you were asking how to transfer fixture unit values from the sanitary system to the vent system, or am I hallucinating?

[RonMaurer]

No post was not edited, but I'll have some of what your having! 🙂 I believe that by setting the fitting to bidirectional and calculated suggested by "pieterdewaal" then the FU count should carry over, but I have not tried this yet. I believe I will do as suggested, but I will modify the transition from 2" to 1-1/2" or 4" to 2" instead of the union suggested. 

Thanks all!!

[iainsavage]

Revit won’t natively run calculations on mixed systems so as @ceyhunyuzuak suggested you probably need to fool it by creating two separate systems connected to some piece of equipment which could pass flows from one system to the other using parameters and formulas.

[pieterdewaal]

If you want to transfer the FUs from the drainage system to the vent system, edit the fitting to be Sanitary-side calculation/Vent-side preset. Then create a parameter called FU, set it equal to the units on the sanitary-side connector as this feeds the parameter value. Then apply FU to the vent-side FU. As preset takes parameters, it doesn't overwrite the calculation.

The issue with this is that pipe fittings have issues with calculations such as this. Perhaps change the family category to a pipe accessory, or mechanical equipment as suggested by others here. Test around and see what works.

[iainsavage]

I think the problem that you’ll run into by using a fitting or accessory is that you don’t have a properly connected logical system to allow Revit to work out flow directions and properly calculate additions/subtractions at branches, so the value picked up by your special connector is likely to be wrong. I’ve never tried @ceyhunyuzuak ‘s method but sounds like the only possible way of doing it so that you use a piece of mechanical equipment which can have multiple systems connected and pass values from one to the other.

Getting off topic slightly, do you actually calculate flows in the vents? Normally I would size vents by rule of thumb - BSEN 12056-2 for example just tabulates vent size against stack/drain size, there is no actual calculation for vent sizes (although it does give a calculation method for air flow for air admittance valves).

[pieterdewaal]

If using Geberit piping, there is no real need to calculate branch vent pipe sizing as they require minimum Ø56 which basically covers most branch cases.

The only time I would normally use larger vent piping would be used is for combing stack vents, such as sovent and supertube stacks, especially for high-rise applications where floors step back in floor area and vent piping needs to run in the horizontal (Ø110-Ø160-Ø200 per stack).

[pieterdewaal]

I realised I never answered your question about sizing vent pipes: Certain standards indicate maximum developed length of a pipe based on nominal diameter and fixture units.

An example of this would be SANS 10252-2. A Ø56 vent pipe with up to 48 fixture units can run 51m in length.