Fixture units vs flow

[veb]

Hello

I am an engineer from Iceland and I have been having trouble with calculating pipe sizes for domestic hot and cold water. Here in Iceland we assign flow to each plumbing fixture ( f.ex. kitchen sink has flow=0,2 l/s) then as they sum up we use a factor equation to calculate the biggest probable flow in the pipe. (We use Eurocode and Danish standard)
Is it possible in Revit MEP to calculate this way?

You use fixture units, which I have been reading a little bit upon. I think I could possibly use that option if the other one is not possible, but I have run into some difficulties. When I have set my plumbing fixture, f.ex. kitchen sink, to flow configuration= fixture units and fixture units=1,0 and then read what my pipes connected say, the hot domestic water says my flow=0.1893 l/s and fixture units=1 which is quite normal but the cold domestic water on the other hand says flow=0.9464 l/s and fixture units=1. The warm domestic water flow seems to be out of the charts for just one kitchen sink! Can anyone possibly explain to me what I might be doing wrong, or maybe I am misunderstanding the way you calculate.

Best regards,

Asdis

[Chris.Aquino]

To help the community get a better idea of what you are seeing, please reply with a small file showing the behavior.

[PCadima]

Hi

I have the same problem if the FU are below 8 the flow rate is always calculated to 0.9464l/s which is excessive (see attached image).

After the FU 8 the volume changes but is still higher that the one indicated in Table E103.3. This is a problem since withought the flow we end up having to manually size the pipework which ends up taking more time.

[konrad.kosiba]

Check pipe system properties and change Flow Conversion Method (for Flush Valves minimum FU in IPC is 5. for Flush Tanks minimum is 1)

[D.Svigir]

Hello,

to everybody. I'm MEP engineer from Croatia and I work in firm which is Autodesk Gold Partner. We work in Autodesk Revit our projects, BIM implementation, trainings and we also are developing tools for simpler use of Revit. Currently we have developed addin for Domestic Water Systems. This addin adds new calculation method for Plumbing Fixtures using FU. Calculation method is based on DIN 1988-W308 norm, also we have added the elevation loss calculation through addin. Applications can calculate critical path based on line pressure loss in pipes and elevation loss.

You can find our application on Autodesk Exchange.

https://apps.autodesk.com/RVT/en/Detail/Index?id=appstore.exchange.autodesk.com%3awatersystemcalcula...

Best Regards,

[maxhough]

Hello,

Would you consider writing a similar app for Australian fixture units?

[D.Svigir]

Hello maxhough,

could you send me some materials about Australian fixture units norm on e-mail: bimline@intelika.hr

I will review sented items and considered about developing app according for Australian FU.

Best Regards,

[fschwartz]

I have not been able to get hot water fixture units to transfer from the hot water water heater connector to the cold water side. I have tried different settings for the connector properties, but none works. If I only connect hot and cold from a faucet to the water heater, I get proper FU. As soon as I create a Tee to feed cold water into the system, the FU's no longer properly calculate. Anyone have a solution?

[fabiosato]

Hello,

You are using the flow configuration as Fixture Units in the connector properties?

If yes this means the connectors properties may look the attached images, right?

I believe you have linked to the fixture units parameter in the connector some instance parameter, and that´s fine.

The problem is that, when the flow configuration is set to fixture units, the behavior is similar to preset setting.

After linking a parameter to the connector fixture units parameter, change the flow configuration to calculated on the hot water connector, if you want to sum the flow in it. The cold water connector can be left as is.

The trick is that you, in the hot water connector, the flow parameter is available, and the fixture units is greyed out, but THE PARAMETER IS STILL LINKED TO THE CONNECTOR, so it will calculate the flow in fixture units.

I hope it is clear enough for you, if not please ask.

[fschwartz]

Fabiosato - thanks for your reply; however, setting connectors as you
suggest does not work for me. Whichever connector is set to calculated has 0
FU and 0 flow. My solution was to set both connectors to fixture units, link
them to FU parameters in the family, and manually enter the hot and cold
FU's that I add up from the connected fixtures into the type properties.



Fred Schwartz

Senior Engineer



Taitem Engineering, PC

110 S. Albany Street, Ithaca, NY 14850

Voice: (607) 277-1118 x102

Mobile: (607) 592-0020

www.taitem.com

[fabiosato]

Hello,

Do you have any fixture units flow source connected to the system?

[ingerick77]

HI

the app is still on line? i can't find it

[bejenaru.a]

Dear D.Svigir

I find your addin quite interesting. 

Could you share with us the Plumbing Fixture-FU table for the DIN 1988?

Thanks