Need help and advice

[Anonymous]

Hi,

I just started learning MEP modeling in Revit (knowing basic operations) and encountered some problems.

1. There is a classification error (it supposed to be a pink, return duct) of ducts connected to the inlet of an air handling unit. This model is from my teammate, and I guess the AHU is not an original model in Revit. Can anyone tell me how to solve this error? Any clues would be enough.

2. In our design, the supply duct of a ventilator is to be connected with the return duct of the AC unit, which is the AHU in 1. And I'm trying to connect the blue supply duct of the ventilator with the return ducts of the AC unit shown below:

Does anyone have any suggestion about how to connect those two ducts, and how to handle the duct classification after joining them?

Thanks for all helps!

[RobDraw]

As to your first question, there are a lot of possible causes. Post that portion of your model to eliminate guessing.

Second question, connected ducts have to be the same system. The connectors in the equipment families at each end of the run need to be of the same classification.

Again, there isn't enough information about the system to give you anything more than a best guess but I think they should both be supply. 

[Anonymous]

Thanks for your answering! I will figure out a way to demonstrate the design idea for Q2. And what portion do you need to eliminate guessing for Q1? The attached file is the AC unit I'm dealing with. Is this enough?

[iainsavage · Accepted solution]

Its not the return connector on the AC unit which your supply duct is connected to, it is a fresh air intake connection which then mixes with the return air inside the AC unit

All the connectors on the unit are set to global and calculated.

I tried it out and the ducts connected okay and took on the correct system settings.

You have to start the duct command, select the correct system then draw the duct from a point towards the connector on the AC unit. The global connector then adopts the system of the duct rather than the duct adopting the system of the connector.

Alternatively you could edit the family and set the connectors to the correct classifications rather than global.

At least that's my best stab at this.

Trial model attached.

[RobDraw]

I thought that might be the case @iainsavage , but there are a lot of possible configurations on these types of systems. I've seen much more with the outside air being dumped into a plenum attached to the FCU, but I have seen a few units that have an outside air intake. With that said, there definitely is something to be said about having the connectors assigned the appropriate system type. Unfortunately, manufacturer's families that try to do this, usually aren't right.

[iainsavage]

PS: I'd suggest having two different supply system type, one for primary outdoor air supply to the FCUs and one for secondary supply (from the FCUs to the air terminals). Then you can have different colours for each, can schedule items separately, apply view filters etc. You maybe also need a third system type for the fresh air intake duct between the heat recovery unit and the external intake cowl or louvre.