Linking multiple point to 1

[Beancud]

Hello all,

I have been struggling about this for sometimes now. I am trying to make a plenum box with spigot for my FCU.

The problem is that when you have one or more connector going into the box it can only link to 1 connector and disconnects the other. This is quite similar to Y bend or split bend in a fitting. To run a correct system the amount entering from A+B+C must equal X.

Such as fresh air 'A' mixing with return air 'B' and another return air 'C' to give a calculated X amount into the FCU.

I was able to somehow conjure a 2 intake system by using the same Y bend theory of A+B connection is linked leaving C connection on its on to discharge the A+B amount.

But when you have 3,4 or even 5 different connection things gets awfully complicated.

Has anyone been able to tackle this problem of mechanical connectors?

I don't know a single soul in my state who has been able to......

Cheers,

[andre.gawlik]

Hi,

Not that this is going to help you with your problem, but I've been trying to figure out FCUs' configurations for some time now (I have posted question in MEP families forum) and I got almost no answers, so it looks that it can't be done - not in this revit's guise anyway.

There's no problem with simple one-to-one systems, but here in UK we use plenums returns and ceiling void mounted FCUs a lot, so You can imagine my frustration of not being able to model them. So far, I had to manually size duct and cap off fresh air duct just to get the right picture out of Revit - not so good for the package that is being marketed as a "designers tool" not a drafting tool.

I had to bite my lip and struggle in silence, because even Autodesk staff doesn't bother to shed some light how to get around some of the system modelling problems....

I hope you going to have more luck than me with it.


Take care and keep calm


Andre

[mjdanowski]

Well if the flow configuration constitutes the problem you are having, I have always done the math through parametric computations.

Create a parameter for each flow value, and then create a "total" flow (or whatever relationship you may want) for the output.

I am not entirely sure if this is what you are looking for, but check out the sample box attached and see if that helps.

[Beancud]

Well if the flow configuration constitutes the problem you are having, I have always done the math through parametric computations.

Create a parameter for each flow value, and then create a "total" flow (or whatever relationship you may want) for the output.

I am not entirely sure if this is what you are looking for, but check out the sample box attached and see if that helps.

Sorry I am not sure what you mean by create a total flow value. I was thinking on the line of "Linking 2-3 connector to the primary connector"

I have something like Total Supply Air Connector as a primary, which gives calcualted amount from 2 linked duct connector, but family editor only allows me to link 1 connector so it is makeing the other connector redundent/ or disconnected.

i.e:

[PRIMARY CONNECTOR-Total Supply] = [1st connector-Fresh Air] + [2nd connector-Return Air]

There is no ability to link two connector to 1 which should give the total value of the 2 linked connectors.

Andre, I have read your previous post and I assure you there are people who has solved that problem. Just not sharing the secret!~ -_-

The ceiling void plenum, we also use it here regularly. I found that the easiest way is to create a invisible/dummy grille to the plenum side. On the drawing the duct will be cut off into the room while the dummy grille is actually connected in invisible mode giving X amount of preset flow from the room. It does get complicated depending on room size. You also need to designate the plenum box to a zone and add a family name profile such as "Kitchen X plenum box". Some people actually shape out an extrusion of the room but I don't see the reason to when you have Zones assigned. But than again it depends on what the plenum is doing.

If this is available it will be extremely usefulf for plant room, duty stand by, backup air smoke, fresh air, cold zone/hot zone etc etc

[mjdanowski]

When you click on the connector's properties, there is a parameter for "flow". This is the amount which the family will set for the flow on that connector. The relationship can go two ways; from the connector to the family parameter or from the family parameter to the connector (depending on whether you have calculated or preset set).

If you want to have an output connector equal the sum of two inputs, all you need to do is make a parametric formula that has "<Input 1> + <Input 2>". Then all you have to do is link these airflow parameters to the connectors.