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Thread: Family using Lookup Table -

  1. #1
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    Default Family using Lookup Table -

    We are trying to create a lookup table to help size air terminals. We've got the table working, but defining Air Flow CFM is key. We are not able to find the correct param_name type definition for CFM.

    We can capture this: pxflow##Volume##Cubic_Feet but can't really convert that to CFM directly.

    What we need is pxflow##OTHER##Airflow ?? or cubic_feet_per_minute or some definition that will accept CFM value. pxflow##OTHER## returns "Inconsistent Units" when we pass CFM value to it.

    Does anyone know if this is possible or where this information could be found?

    Appreciate it; the forum is always helpful.

  2. #2
    Revit Forum Manager Steve_Stafford's Avatar
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    Default Re: Family using Lookup Table -

    The format Revit expects is: Flow##HVAC_AIR_FLOW@@CUBIC_FEET_PER_MINUTE

    That said I suspect what you want to do runs counter to what Revit's workflow or expectations are. Revit expects that we provide a desired Air Flow at terminals (whether supply, return or exhaust) as a desired goal or criteria. The Duct Sizing feature is predicated on providing this at each terminal. It sounds like you are hoping to have this value supplied from a lookup table which sounds like a chicken and egg problem. Obviously I don't understand your approach or goal completely.

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    Default Re: Family using Lookup Table -

    Thanks Steve! Yes, that is understood, we will have user supply the CFM when air terminal placed and from that the duct will size. I looked everywhere for this definition. Appreciate it. I'll let you know how it works out.

    ann

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    Default Re: Family using Lookup Table -

    Worked like a charm. Is there a master list somewhere. Or is it just an obvious extrapolation? HVAC_COOLING_LOAD##BTU_PER_HOUR for example.

    This would open up a lot of possibilities.

    Very helpful, thank you, Steve.

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    Revit Forum Manager Steve_Stafford's Avatar
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    Default Re: Family using Lookup Table -

    That is the general format syntax for MEP parameters. Just note the @@ versus ## though. I do remember reading a blog post in the past about formatting parameters in type catalogs but don't remember which one at the moment. I don't recall a master list though the wikihelp might have added some info. If I'm not sure I usually create a parameter and then use Export Family Types to a analog just to make sure I've got the format correct.

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    Default Re: Family using Lookup Table -

    I'll make a note of the @@. Thanks again. As always, you are a great help.

    ann

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    Revit Forum Manager Steve_Stafford's Avatar
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    Default Re: Family using Lookup Table -

    Sorry, managed to confuse myself! I typed @@ in my first example, but that is WRONG, it is a typo!! It should be ## in both instances, very sorry!
    Last edited by Steve_Stafford; 2013-06-27 at 01:19 AM. Reason: ironic, made a typo fixing a typo

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    Default Re: Family using Lookup Table -

    There is one book I have found that gives a list of "Valid Unit Types and Values For Each Dimensional Type", don't know how definitive or up to date it is given it was created for Revit 2010, and I know there are at least some parameter types added since then.

    Revit 2010: Family Standards and Best Practices by Shawn Zirbes & Integrated Content Solutions
    The latest version of Autodesk's families guide also has a list. That latest version is also 2010 however

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    Revit Forum Manager Steve_Stafford's Avatar
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    Default Re: Family using Lookup Table -

    Fwiw, I decided to write a blog post on the subject tonight too.

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    Default Re: Family using Lookup Table -

    No worries. Funny, though. @@ worked?? Changed it back. Good topic for blog post, I agree. It was really hard to track this info down. I was so close in my experiments, but never hit on the right type definition.

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