Go with the Flow… for Hydronic Baseboards

Hydronic baseboard (HBB) heat works a little differently than most systems in Revit MEP. And there doesn’t seem to be a good out-of-the-box (OOTB) solution.

Most systems in Revit function by totaling the flow of the terminal units at their source equipment (i.e. five air terminals with a flow of 100 cfm will report 500 cfm at the Terminal Air Unit (TAU) that feeds it.) HBB flow a given amount through a bank of units (i.e. 3 six foot units under a lobby storefront each have a flow of 5 gpm) which will report back to the boiler that feeds them. That boiler will then report an aggregate of all banks of HBB and any other Hydronic equipment connected to it. See the example below:

To get the baseboard to behave as expected, we must configure the connectors so that they recognize what system they are on and propagate the flow from one connection to another without adding to it. Also, to make it convenient to place the units, it would be nice if you could connect them without regard to flow direction (within the HBB family.)

By setting ALL of the connectors as follows, they will pick up what system they are connected to (Global,) how much is flowing through them (Calculated,) and which direction the equipment it is connected to is flowing (Bidirectional.) Also, “Link” the connectors that are on the same side (that way flow will pass “out” one side and “back” the other.)

The key to getting the system to work, is to have a piece of equipment that controls each bank of HBB. In reality their is a valve/regulator that controls how much and when there is flow through that particular bank of HBB. I created a very simple family that has a supply and return piping connector that are “preset” (which lets us define how much flow is on this bank of HBB) and mapped to the “Flow” parameter (which is a shared parameter so that it tags and can be scheduled) of the family.

Below is a quick video clip that shows how you can control your HBB with this simple family. It also serves as a reminder of how you can change parameter values through a tag.

Note: you can change both Instance and Type parameters in a tag (remember that when you change type parameters you are changing ALL instances of that type. Don’t worry, Revit will remind you.) If you want to prevent users from changing a particular parameter in a tag, make it be “Equal” to a parameter that isn’t a Shared Parameter. Also, placing that parameter under the heading of other and giving an official name (such as “System Flow”) reduces the chances that a user will try to change it. :)

Can't see objects through a link? Try this...

I've known about this issue for awhile, but a post over at the Revit Garage brought it to the front of my mind when we were having an issue with linked file where we couldn't see any geometry in the host file. Note: you can set each view in the host file so that the Link is "by linked view" but that is a view specific setting and not really practical.

If you have checked all the usual suspects (visibility of model elements in Visibility Graphics/Overrides, Worksets (we put each link on it's own workset) etc, etc) and you still can't see the objects you're after, it could be that the workset the objects are on was not set to be "Visible by default in all views."








Old News, really, but here's the tip. To quickly transfer that invisible geometry to a new "unmarred" workset, follow these steps:


Create a new workset. Call it something like "Test." (You'll change it later.) Make sure it IS visible by default in all views.


Select the offending workset and click "Delete." Note: there is no way to change the setting that is causing the issue. You have to move the geometry to a visible workset.


When you do this, you are given the option of deleting the objects on that workset or... cue drum roll... select which workset to move them to. Select the new workset from the drop down list. Now you can rename the new workset to match the old one and no one will be the wiser.





Where you aren't able to do this is if the offending workset is (or originated as and was renamed) Workset 1. When you select that workset "Delete" is greyed out. As a practice we rename the default Workset 1 to Coordination and only use it as a holding pen for "lost" items.






Here is another quick video to help explain. I apologize for going a little fast. Actually I just watched it and it is a little confusing since it isn't narrated. If you have questions, be sure to post them here. Sorry that there's still no sound. Quality microphones don't grown on trees. ;)

The Revit X-Files

The truth is out there... I think.

So this is a new category of posts here at Big Bad BIM. Reminiscent of Revit OpEd's Department of Unfair. This will be the repository for all the freaky,weird, off-the-wall Revit stuff that just drives me CRAZY!!!


I think Autodesk calls these "service requests." Ok, ok, I'll try to log those too.


First installment comes from our Mechanical Engineering department. One of our user's was trying to use the "Tag All Not Tagged" tool to tag all of the ceilings in a view. He just couldn't get it to work. He could tag them one at a time, but not all.


Wondering if it was something related to that particular project, I tried it in a view that was set to the Architetural discipline as opposed to the Mechanical discipline. Sure enough, no problem. I changed the view in question to an Architetual discipline. Tagged All Not Tagged and changed it back. Worked great. Work-around? You bet, but we have lots of those.

Back at my desk, I wanted to make sure I hadn't missed something. So I compared the element properties of a couple of views.Here are the results (notice in particular the "underlay orientation"):


Architectural Discipline:



Mechanical Discipline:




Note: the Mech view didn't default to "Plan" for the Underlay Orientation. I changed it. I CHANGED IT!!! You shouldn't be able to do that. That parameter allows you to underlay a ceiling plan in a plan view (so you can coordinate overhead information with your floor plan.) I don't think we were meant to access this in a ceiling plan.

Are these two conditions related. Is it a programming bug? Aliens that have it in for HVAC designers? Who knows, but it sure is weird (not to mention frustrating.)


Here a couple of ceiling related videos. First is a video that shows the workaround mentioned above. The second is a video that shows how to apply filters (powerful little buggers, those filters) that make "non-standard" ceiling heights really "pop," which really helps when coordinating information in the model.

A BIM filled week

It has been long week already, and it's only Wednesday!

Monday was the first meeting of the Madison MEP User's Group that I have attended. Being new to the area it was great to be invited. Thanks to Westphal Electric for hosting and thanks to Scott Brisk (Revit MEP blog) for facilitating (thanks for the invite Scott!!) There was no particular application affinity in this group, although it seemed to be weighted towards Autodesk products. This seems like a great group of folks and it's always nice to see what other BIM users are doing out there. Model to fabrication, and Model to total station "round tripping" are two topics that were mentioned a number of times (and probably deserve a follow up post.)

This morning, Ed Deal (AEC Building Technical Specialist for Autodesk) presented a seminar in two sessions. The first was titled Construction Documents and Beyond. The focus was on breaking out of the Construction Document (CD) trap. While Revit can produce 2D printed documents that rival anything ever produced in CAD (when set up well,) it is at heart a design tool and in it's soul is a BIM authoring tool. Needless to say, lots of ideas about verifying programming, quantifying design iterations and schematic analysis were presented. My kinda topics.

The second session was geared towards the MEP crowd ( it was nice to see faces from the Madison MEP User's Group again so soon.) The topic was analysis tools that leverage the Revit Model. Starting with a very schematic model (approx 45 mins of modeling) Ed analyzed various design iterations using the tools available natively in Revit, Green Building Studio, and Ecotect. Some of the things that Ed did I'm not sure you can even DO with CAD drawings (certainly not with the level of accuracy and in the same amount of time.) I'll try to post links to the White Papers referenced. Thanks ED!

Tomorrow we (Cogdell Spencer Erdman-Madison Office) host the Madison Revit Managers Group. So hopefully we will have some useful blog-fodder from that meeting as well.

In the next couple of weeks, expect posts about:

Ceilings (the videos are already on my YouTube Channel) note: would have posted about these earlier, but my laptop went 10 rounds with a small dog and lost it's "C" key. I just can't "see" posting about Ceilings without a "C." :P

An update to Plumbing "Fixture Unit" Flow. (Hint: I think we found a way to make it work.)

Is Revit faster than CAD? (a definitive answer...?)

etc etc.

If you don't see these soon, you need to get on here and nag me till they show up.

Thanks all,

E

"Family Type" Parameter in a Type Catalog Part 2

JING is great, but the .swf files are a pain to embed on Blogger.

Who's afraid of the Big Bad BIM? finally has a YouTube Channel. Hooray for technology.
The quality still isn't great. From Jing (freeware) through a trial .swf convereter (also free) to YouTube. I guess I will have to spring for Camtasia after all... Fathers day is coming... Hmmmmmmm.

I recommend viewing AT YouTube's site>Clicking the HD button for higher quality>and watching in full screen.

"Family Type" Parameter in a Type Catalog

They say that absence makes the heart grow fonder. Let's hope so fans. Of course I think the actual quote is "Absence makes the heart grow fonder... for someone closer." If that's the case, I hope my favorite Revit bloggers got a bump in readership. :)

In a comment on an earlier post, a reader asked if it is possible to drive Nested Families with a type catalog. In a subsequent email he issued a friendly challenge to prove that it can be done and show if a Yes/No parameter can also be controlled as well.

Nothing will get me blogging faster than a challenge. Thanks Matthijs.

What follows are links to a couple of quick video clips that I hope explain how it can be done.

Showing the Parameter Types

Loading and Placing the Family

(bonus: note that you can drive "instance" parameters with a Type Catalog)

Here is the Type Catalog. I always like to create and edit my type catalogs in Excel and then save to .csv format and change the extension to .txt. It's just easier for me.

As you can see in the second clip, I alternated each parameter value. Just make sure that you spell the "Family Type" parameter the way it appears in the value cell in the Family editor.

Oh, and the 0's and 1's? Binary, Baby! 0=No 1=Yes.

Good luck, and keep the challenges coming.

Revit MEP (Plumbing) Piping Flow: another second class citizen

Warning: What follows is a rant fest filled with WAY more information about MY ideas of how both plumbing design and Revit MEP work. Any deviation from reality on either subject can wholly be attributed to a 14 month old daughter, a pregnant wife and a looming Revit configuration deadline. Please excuse my definite lack of plumbing design knowledge. See one, do one, teach one, I always say.

Revit MEP is ALL about propagating information throughout the model.

Spaces can be assigned a required Air Flow value.
Air Terminals know what space they are in.
Spaces know how much Air Flow is coming from the Air Terminals it contains.
Duct connected to an air terminal knows how much air is flowing through it (based on what the terminal is providing to the room.)
Variable Speed Fans (VSF) know the SUM of the flow from all the terminals connected to it downstream (Revit is doing the math on the fly.)
And so on and so forth all the way back to the Roof Top Unit (RTU) that SUMS all the VSF (and therefore all the terminals) that are connected to it.

We can tag and schedule this information fairly easily. And, it's used in sizing calculations.

Sounds keen.

Enter Plumbing pipe systems. (Cue ominous musical score.)

On the surface they work similarly to HVAC duct systems. But any plumbing designer will tell you (you have to listen closely they probably won't repeat it) that flow through a plumbing systems is different than duct systems. It's even different than flow through hydronic, or process systems.

The difference is DIVERSITY. No we're not talking about multiculturalism. Simply put, a system that contains 1 watercloset (WC) (that's toilet to the rest of us) has a 100% chance that all WC will be flushed at exactly the same time. Therefore the system is designed to accommodate the flow of that WC. A system with 100 WC has about a 0% chance that ALL will be flushed at the same time (aside from High School pranks.) Plumbing designers use a diversity factor along with Fixture Units (FU) to determine the most likely (design) flow in their systems. FU are assigned to fixtures (WC, sinks, etc) by Authorities Having Jurisdiction (AHJ(why is it always a TLA(Three Letter Acronym?))) so they can vary by locale. In short the designer totals the FU on a system and applies the diversity factor (which they get from a table) for the number of actual fixtures and that tells them the flow they need and therefore the pipe size. Whew! (Did I really have a 3rd level parenthetical statement back at AHJ?)

Why does all this matter? Well, for one, Revit doesn't get to look at that diversity factor table when it's computing flow. I can't even imagine the math used to derive flow from FU without it. All in all Revit does a darn good job of computing that flow and reporting it out to us. Connect a bunch of sinks to a pipe that connects to a water heater and the pipes will total the FU (and the resultant flow) from however many it is actually connected to.

Now the rub. The pipe that connects to the equipment (water heater) reports it's FU and flow fine, but NEITHER THE FU OR THE FLOW propagates to the equipment. You can create family or shared parameters based on both FU and flow. However, when mapped to the same parameters on the family's connectors (similar to how you cause Air Flow to propagate through VSF) you receive NO report. And, it will not propagate upstream.

At least I can't get it to work (and I tried every combination of connector settings related to those two parameters.) After talking with an Autodesk rep, it came to my attention that Revit MEP wasn't designed to pass flow through equipment in plumbing systems (where flow is calculated from FU.) So that means, I can't schedule equipment (like water heaters or softeners) and have the schedule show the actual flow demand on the unit (based on the system it is connected to.)

A bug? Unforeseen functionality need? I think it's just that the Revit code jockeys took it the wrong way when they were told to work on the FU systems...

BTW, this has been logged as a functionality request to the development team. Here's to making plumbing flow as useful as it's first class cousins Air Flow and (hydronic) piping flow. :)

Trouble finding hidden elements in Revit? Use; Select by ID

This handy feature can really save you when you are trying to figure out what objects are causing issues in your project.

The other day I was trying to resolve some warnings related to switching a wall from one type to another that was not as wide in section. I wish that I had taken a screen shot of the warnings... there were 18 warnings (cannot be ignored) and 9 errors (Revit telling you that you should pay attention and see if what you just did was really what you meant to do.)

The project was fairly far along (actually CDs have been issued, but there is some clean up going on in the model.) Swapping walls at this stage can cause all sorts of issues.

In this case all of the warnings and errors were related to a ceiling. I created a new section and oriented a duplicated 3D view to it so that it encompassed the wall in question. I selected the ceiling in the warning tree and clicked the "Show" button but it wouldn't highlight in the view.

So, I wrote down the ID number (you can't copy/paste here, so you have to go old school.)

(I guess you could screen capture like I just did to get this image though.)

Now, go to "Tools" Drop-down menu>Element IDs>Select by ID

Enter the # into the dialog and now you can either use the "Show" button to highlight the element, or the "Select" button to grab the item and modify or delete it.

If you are trying to scout something that is deeply hidden in the model:

Duplicate the Default 3D view

Use the Select by ID feature

Use the "Isolate Element" command (click the eyeglasses) to hide everything else in the project.

Now you can activate the Scope Box for this view and crop out most of the model to get a better idea of where the elemnt is and what may be causing your issue.

Good Luck and Good Hunting.

The Key to Giving 100%

I don't really like to link to others Blogs. But you just can't argue with logic.

Autodesk 2010 Design and Engineering Software Product Line Now Available

YAY!!!

I hope you're on subscription and your copy is in the mail...

Follow the link to the full press release.