Revit 2024 - Correct Connectors for flow through Valve (Pipe Accessory)

[jeremy.colombe]

Been using the same in house created valves for years. Got through all the connector issues. Used a Steve Stafford approach of setting both connectors to "fitting" and linking the connectors. Now the family seems to be "reading" the flow direction in Revit 2024 and connects in one system (DCW) with the proper flow but throws the connecting in wrong direction error or connects to the backside of the valve in the DHW system. Tried going Global / bidirectional / calculated and preset for the other but same issue. Tried everything I can think of. I just want the valves to break in, connect properly, transmit flow and ideally be able to impact pressure drop but the P drop is not 100% required. @HVAC-Novice tagging you because I read you had success with the global, bi-directional, preset, calculated method. Were you pushing any data around with parameters or something?

Thanks in advance. Its been a long Friday afternoon haha.

Appreciate any help

[iainsavage]

Upload the family please.

Also do you just want the valve to pass the flow through from one pipe to the other or do you want the flow to to be able to be read in the valve properties?

[jeremy.colombe]

Came at it with a clear head and got it to work but stumped as to why it happened. In the end I "flipped" around the connectors in the family and updated a nested if statement within the family as it seems to only have trouble below 65mm. Working now but not confident.

The valves would want to connect to the wrong side of the pipe in the smaller sizes. I thought it was system related but believe it was size. 

Valve family's attached Rev 2 was the one that worked. Both Revit 2024.

[iainsavage]

Most out of the box valves have the connectors as Global and Bidirectional with the connectors linked.

There is no need to link connectors set to Fitting, they are inherently linked and bidirectional already.

Note from the official help: Linked connectors only have an effect when the System Type is set to Global, which is common for fittings and in‐line components such as dampers, valves, and pumps

[jeremy.colombe]

Ok Cool. My family currently does not have the connectors linked but one is set of calculated global, other is preset global, bidirectional, and both connectors "flow" is set to the same parameter. What does linking versus unlinked connectors do when the system is set to global? Sounds like I should have it linked.

[jeremy.colombe]

Also appreciate the help!

[iainsavage · Accepted solution]

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@jeremy.colombe wrote:

Ok Cool. My family currently does not have the connectors linked but one is set of calculated global, other is preset global, bidirectional, and both connectors "flow" is set to the same parameter. What does linking versus unlinked connectors do when the system is set to global? Sounds like I should have it linked.

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Linking connectors passes the flow from one connector to the other but only for Global classification.

Both of your connectors would usually be set to Calculated - they will read the flow from the connected pipes.

Preset is only used generally in equipment and is used to set the flow value via a parameter, such as setting the flow required at an air terminal or a fan coil or radiator etc.

In main mechanical equipment you can use Calculated/Preset pairs to pass flow through say an air handling unit or boiler or chiller etc which might have several connectors of different classifications (say Hydronic Supply in, Hydronic Supply out, Hydronic Return in, Hydronic Return out) you would set one connector of each pair to Calculated and the other connector of each pair to Preset. The Calculated connectors would inherit the flow from the connected pipes, then pass the value to a parameter which would pass the value to another parameter which would then pass the value to the Preset connector.

Maybe that is what you are trying to do with your valve family but that should not be necessary for simple "in-line" components such as valves, dampers, pumps, fans which only have two connectors and just need to pass flow directly from one connector to the other.

[jeremy.colombe]

Ok perfect. S. two calculated parameters, linked and set with a shared parameter for flow. I just want valves that are universal for all systems but pass through flow and ideally I can setup for P drop later.  With two calculated parameters are you putting P drop in one of them or both?

[iainsavage]

"two calculated parameters, linked and set with a shared parameter for flow" That's not what I said. That is a method for more complex equipment.

For a simple valve you should just have two Global connectors, Bidirectional, linked.

If you associate a flow parameter to the connectors it will be a read-only parameter and will display the value which the connector has inherited from the connected pipes

Regarding pressure drop, the best method is to apply this to the family as a factor so that it will adjust the loss depending on the flow value.

or

[jeremy.colombe]

Yeah I got my set to specified for now because we are small and not using the p drop. Intend to setup the Cv K values at some point. Are you putting one of the calculated connectors to no drop and the other K value based?

[iainsavage]

You can apply the pressure drop to the family via a parameter as I showed, rather than the connectors.

Be careful with Cv or Kv values they are NOT the same as K-coefficient,

https://forums.autodesk.com/t5/revit-mep-forum/kv-or-cv-versus-k-coefficient-for-valves-etc/m-p/6471...

[jeremy.colombe]

You still need to have the pressure drop included in the calculation and the only way I found to do that was to apply it to the connector. Or are you exporting the p drop values outside of revit for calculation? 

Very interesting on the Kv Cv and k coefficient. That explains a few things for me haha.

[iainsavage]

When you create a new pipe accessory family from the generic model template and set the category to pipe accessory the pressure loss parameters are automatically created:

These apply to the Family, not to the connectors.

Select a method and value. For my example I used 

If you try to apply a pressure parameter to the connectors it will be greyed out

In the model the pressure drop calculates dependant on the flow value through the accessory:

In the pressure loss calculation the pressure loss of the accessory is included in the system loss:

There is no pressure parameter associated to the connectors, it is built in to the family.

[jeremy.colombe]

Holy Poop!!! Did not know that was possible at all! That is cool. That is as big as tagging area in a detail item family lol.