topic Re: VAV Text Parameter won't display in VAV Schedule in Revit MEP Forum

VAV Text Parameter won't display in VAV Schedule

jordan_frey — Thu, 21 Mar 2024 13:14:43 GMT

I am trying to get the text parameter that's inherent to my VAV family to show up when I create a VAV schedule (I would like 'max cfm' values to populate under airflow column), however when I view the field window to apply to get what I want to show, it does not appear in the window. Is there a workaround for this? It should be fairly simple thing to do and will make creating/verifying schedules in CAD more streamlined, but I don't know if it's a shared parameter limitation.

Any ideas? TIA @Kevin.Lawson.PE

Re: VAV Text Parameter won't display in VAV Schedule

iainsavage — Thu, 21 Mar 2024 13:28:17 GMT

It is probably a Family parameter which will not appear in schedules.

Create a Shared Parameter and load it into the family file.

Insert a formula for your new shared parameter = Max CFM.

Reload the family into your project.

Use your shared parameter in the schedule. Edit the column header name if you wish

Re: VAV Text Parameter won't display in VAV Schedule

iainsavage — Thu, 21 Mar 2024 13:34:34 GMT

You can also try this method (its not the way that I've done it before)

https://help.autodesk.com/view/RVT/2022/ENU/?guid=GUID-18575F0E-A0F3-4032-8BAF-205991E3F3A4

This explains differences between different parameter types and their behaviour.

https://help.autodesk.com/view/RVT/2022/ENU/?guid=GUID-AEBA08ED-BDF1-4E59-825A-BF9E4A871CF5

Re: VAV Text Parameter won't display in VAV Schedule

HVAC-Novice — Thu, 21 Mar 2024 15:34:18 GMT

I create a shared parameter to read the actual airflow from the connector. This will be the maximum flow.

For minimum or a lower heating flow, I use a separate shared parameter I have to enter manually. but at least the max value is automated.

Re: VAV Text Parameter won't display in VAV Schedule

iainsavage — Thu, 21 Mar 2024 16:04:08 GMT

I think that in these types of families the Max CFM is supposed to indicate the recommended maximum flow through the equipment/terminal to limit noise and pressure loss rather than representing the actual design flow (peak flow for a VAV system?).

Re: VAV Text Parameter won't display in VAV Schedule

jordan_frey — Fri, 22 Mar 2024 14:42:09 GMT

@iainsavage I was able to create a shared parameter, "Supply Airflow" and load into the project, however, I need this to be a manual entry where I can enter in the design airflow so I can apply different values of cfm depending on the VAV/room being served. I want this to carry over to my Revit schedule so I can see the VAV numbers next to the cfm for each. It appears to be "locked out" as I can't just enter in my cfm as I did before using a text parameter.

Re: VAV Text Parameter won't display in VAV Schedule

HVAC-Novice — Fri, 22 Mar 2024 14:55:41 GMT

make it an instance parameter.

If you use the actual flow in the ducts, you can automate the max flow and don't have to edit manually.

Re: VAV Text Parameter won't display in VAV Schedule

iainsavage — Fri, 22 Mar 2024 19:28:47 GMT

@jordan_frey wrote:
@iainsavage I was able to create a shared parameter, "Supply Airflow" and load into the project, however, I need this to be a manual entry where I can enter in the design airflow so I can apply different values of cfm depending on the VAV/room being served. I want this to carry over to my Revit schedule so I can see the VAV numbers next to the cfm for each. It appears to be "locked out" as I can't just enter in my cfm as I did before using a text parameter.

Your screen captures don't make sense. In one capture you have Design Flow as a Type parameter and Supply Flow as an Instance parameter but in the other capture you have Supply Flow as a Type parameter.

Your original question was how to schedule the Max CFM family parameter.

What you now seem to be wanting is to apply design flow rate to the diffuser and VAV, so:-

In the diffuser family create a Shared parameter as an Instance flow parameter.
Assign that parameter to the connector on the diffuser.
The connector should be Preset, Supply, In.
Load into project.
You can assign flow rates to each individual diffuser and these flows will automatically pass into the duct system and totalise through the system.
In the VAV family create an Instance, Shared, flow parameter and assign that to the connector on the room side of the VAV. Make the connector Calculated, Supply, Out.
On the other side of the VAV unit assign the same shared parameter to the connector and make it Preset, Supply, In. This will pass the flow through the VAV unit and you can schedule it.

See attached document and this excerpt from it: