topic Re: Pipe flow calculation by creating shared/Project parameters in roof drain in Revit MEP Forum

Pipe flow calculation by creating shared/Project parameters in roof drain

Dipendra_yadav — Fri, 03 Sep 2021 23:12:16 GMT

I have modified the roof drain family and assign the area and rainfall to calculation flow(GPM) . The family works fine but when I connect the pipe to the family the flow is not reflected on pipe. Please refer the attached file.

Thank you,

Re: Pipe flow calculation by creating shared/Project parameters in roof drain

iainsavage — Sat, 04 Sep 2021 09:25:24 GMT

It would be best to upload your family for testing.

The pipe connector should be set to Preset, Out and Sanitary.

Its flow value should then be associated to your flow parameter.

Your pipe system in the project would also be Sanitary classification for roof drainage.

Re: Pipe flow calculation by creating shared/Project parameters in roof drain

Dipendra_yadav — Tue, 07 Sep 2021 17:52:15 GMT

Hi, Thanks for you time. I am trying to assign parameter and use hydronic return piping to calculate flow, the flow shows in the roof drain but not in the connected pipe. I have attached the project file and family file. Please refer the video ( 6:20-9:21) This is what I am trying. Thank you.

https://www.autodesk.com/autodesk-university/class/Automating-Plumbing-Design-Revit-2016#video

Re: Pipe flow calculation by creating shared/Project parameters in roof drain

iainsavage — Wed, 08 Sep 2021 06:27:25 GMT

Its the Hydronic Return classification which seems to be causing the issue.

When I change it to sanitary it looks for fixture units (even though the connector is set to Preset rather than Fixture Unit).

Domestic Cold Water works though.

PS: did you mean to have two outlets in the family, one of which doesn't have a connector?

Re: Pipe flow calculation by creating shared/Project parameters in roof drain

Dipendra_yadav — Wed, 08 Sep 2021 21:52:46 GMT

Thank you,

The intent of using hydronic return is that I want to size the roof drain pipe based on GPM(flow) not the Fixture Units(FU). I understand it works fine when we use sanitary system.

What I am trying to do is tested by someone. Please refer webinar in below link. Can you please have a look from 6 minutes to 9 minutes.

https://www.autodesk.com/autodesk-university/class/Automating-Plumbing-Design-Revit-2016#video

Re: Pipe flow calculation by creating shared/Project parameters in roof drain

iainsavage — Thu, 09 Sep 2021 05:59:33 GMT

I've seen that video before but had never tried it for real.

All that I can tell you is that it doesn't work with Hydronic Return in your project or in my test project.

System Inspector shows confusion over flow direction and zero flow in all pipes.

With the classification changed to Domestic Cold Water it works correctly and reports flow values, not fixture units.

(Preset = constant flow not fixture units. Fixture units are only activated with the Fixture Unit option)

The other option that I tried was to leave the system as Hydronic Return but changed the floor drain family to Mechanical Equipment and that also works:

Maybe, given the age of that video, there has been a change in the software and now maybe "mechanical" pipe systems aren't compatible with plumbing systems?

So my recommendation is change your connector to Domestic Cold Water, Preset, Out.

Note that these "flow" values are actually the catchment areas of the drains because you haven't put in the formula for sqft to gpm yet.

Re: Pipe flow calculation by creating shared/Project parameters in roof drain

Dipendra_yadav — Thu, 09 Sep 2021 16:54:33 GMT

Thank you for your time. Yes, it works with Domestic cold water system.

Re: Pipe flow calculation by creating shared/Project parameters in roof drain

cbeliveau5TAHS — Mon, 04 Oct 2021 11:43:46 GMT

Link the flow parameter to the connector and that should solve the issue.

Re: Pipe flow calculation by creating shared/Project parameters in roof drain

iainsavage — Mon, 04 Oct 2021 18:50:30 GMT

@cbeliveau5TAHS wrote:
Link the flow parameter to the connector and that should solve the issue.

That wasn’t the issue. It was the system category which was incompatible with plumbing fixture family per the marked solution - just for any future readers.

Re: Pipe flow calculation by creating shared/Project parameters in roof drain

cbeliveau5TAHS — Wed, 06 Oct 2021 19:48:34 GMT

I have a similar setup using hydronic and worked. I'm curious what was not compatible.

Re: Pipe flow calculation by creating shared/Project parameters in roof drain

iainsavage — Wed, 06 Oct 2021 22:34:04 GMT

Parts 4 and 6 explain it.

The flow parameter was associated with the connector, obviously, but with the OP’s choice of Hydronic Return and Plumbing Fixture the flow did not transfer into the pipes.

The video which they posted the link to did work with that combination and on that basis I suspect that this behaviour might be version-dependant.

The issue was solved by using Domestic Cold Water instead of Hydronic Return.

If you have it working as the OP originally wanted then please explain how, or share a copy of your model.