Author Topic: Duct System Blending  (Read 954 times)

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Rob...

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Duct System Blending
« on: January 10, 2017, 08:02:26 am »
I'm curious as to the proper way to do this.

System description:

Outside air through ERVs to bring it up to a minimum temperature for ventilation air to heat pumps which recirculate some of the room air. Room air gets mixed with the ventilation air prior to going back to the heat pumps. Exhaust air going back to the ERVs is equal in volume to the ventilation air.

How many systems are needed? I'm thinking ventilation (conditioned OA), Supply, Return, and Exhaust at a minimum.

Would you make a separate system for that mixed air (ventilation and return) going back into the heat pump? It's basically a plenum that has both ventilation air and return air going through to a common output.

How would you mix the systems, ventilation and return? Does it need to be a plenum (or something else) that mixes the systems or can it be a duct?
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John Kaul (Se7en)

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Re: Duct System Blending
« Reply #1 on: January 10, 2017, 09:45:26 am »
You can tie two systems (duct to duct) together but the whole mess is VERY fragile -i.e. as soon as you connect/change systems again all associated and attached get all redefined. The easier solution is to create a mixing box family but you still only have a few built-in systems to choose from (SA, RA, EA). ...Yes the systems can get a bit tricky -i.e. exhaust air, tempered air, supply air, and return air but you're just going to have to "not fully connect" (if you establish all those duct systems)--but then you loose part of your calculations--or deal with the built-ins (SA, RA, EA)--potentially loose colors on the screen-.

FWIW: My systems are SA, RA, EA, & OA. and these are only for colors on the screen (in working views). The built-ins are really only to establish "symbols" (Cross, Slash, Wye) in the rises and drops and for calculation purposes.

Generally speaking in an average duct system you can have:
Supply
Return
Exhaust (Lab/Chemical/Biological & General)
Relief
Outside
Tempered


You <-- Grain of salt.
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Rob...

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Re: Duct System Blending
« Reply #2 on: January 10, 2017, 10:42:40 am »
You <-- Grain of salt.

What exactly does that mean?
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John Kaul (Se7en)

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Re: Duct System Blending
« Reply #3 on: January 10, 2017, 12:21:40 pm »
Take whatever I said with a grain of salt.

https://en.wikipedia.org/wiki/Grain_of_salt
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Rob...

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Re: Duct System Blending
« Reply #4 on: January 10, 2017, 01:06:04 pm »
Okay, thanks.

At first, I thought you comparing me to something less than a grain of salt. I did think of that saying but I didn't see how it fit here.
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Rob...

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Re: Duct System Blending
« Reply #5 on: January 10, 2017, 01:38:07 pm »
I've decided to try it with a duct for no other reason than I don't want to figure out how to tag a plenum/mixing box right now.

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John Kaul (Se7en)

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Re: Duct System Blending
« Reply #6 on: January 10, 2017, 03:33:06 pm »
Sounds good.

BTW, those better not be colors driven by "graphic overrides" (like in the default revit templates). ...just saying.
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Matt__W

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Re: Duct System Blending
« Reply #7 on: January 10, 2017, 04:14:54 pm »
Sounds good.

BTW, those better not be colors driven by "graphic overrides" (like in the default revit templates). ...just saying.
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Rob...

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Re: Duct System Blending
« Reply #8 on: January 10, 2017, 04:19:03 pm »
"I don't need no stinkin' standards."

Actually, I'm not even sure what is not an override other than the default white/black.

The colors are assigned by system graphic overrides. Trying to keep it simple as we bang out the first couple of Revit projects this company has had. Everyone is into it, so far. Quite a different experience compared to what happened at my last place when we first started out with Revit. Oh, that was bad...
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John Kaul (Se7en)

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Re: Duct System Blending
« Reply #9 on: January 10, 2017, 04:23:11 pm »
I only have two words to say to you: your plotting will be fun (read: crappy)!
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Rob...

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Re: Duct System Blending
« Reply #10 on: January 10, 2017, 04:25:09 pm »
No problems with plotting. Why do you say that?
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Rob...

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Re: Duct System Blending
« Reply #11 on: January 10, 2017, 04:28:27 pm »
What is going on here? First you say I'm less than a grain of salt and now my plots will be crappy? I haven't felt this insulted in a while.
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John Kaul (Se7en)

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Re: Duct System Blending
« Reply #12 on: January 10, 2017, 04:30:55 pm »
Plotting "black lines" doesn't work great with screened lines and "greyscale" doesn't give you the best control over things either. ...you should be working in "working views" with colors and have your "plot views" filters set the color to no color.

...ha! I think I still have his email address if you want it.
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John Kaul (Se7en)

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Re: Duct System Blending
« Reply #13 on: January 10, 2017, 04:31:52 pm »
And, what kind of insult is "less than a grain of salt" anyways!?
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Rob...

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Re: Duct System Blending
« Reply #14 on: January 10, 2017, 04:48:07 pm »
I've been using black lines for years and am satisfied with the results. Our plots could be better and I'm pretty sure I can get there utilizing black lines, but at this point, why bother? Color plots are right around the corner and that is an entirely different beast. They already have a large format color plotter. Plus, their AutoCAD plots are fairly simple and could use a lot of refining. As long as the bosses are happy, less that I have to worry about at this point. Like assigning pipe system colors, plotting is one of those things that I can drive myself crazy with. I've got bigger fish to fry. Gotta wean them off the AutoCAD teats. So far, it's just floor plans in Revit.

I have working views. They actually look quite similar except for seeing the other trades, a higher detail level, and have no annotation, although I could use them for notes.

As to the email, thanks, but no thanks. LOL!
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