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RJServoss
Posts: 16
Registered: ‎07-14-2011
Message 1 of 6 (351 Views)
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How do you select equipment for parallel systems?

351 Views, 5 Replies
01-30-2014 05:15 PM

My mechanical system has 2 air handling units connected via a plelnum. I have the duct connector on the unit set to Flow Configuration - System, with a flow factor of 0.5, so that the system flow will then be distributed evenly to both of the air handling units. My problem is that I don't know how to select both pieces of equipment for the system. When I go to the system selector and select equipment, it doesn't seem to allow both of the air handling units to be selected as the equipment serving the system.

It's a bit confusing as you would think that since the equipment is in parallel that in the system browser they would be at the same location in the hierarchy, but that is not the case. If you simply add the other piece of equipment to the system through the "edit system" "add to system" command, your system flow configuration and your flow factors will work correctly. You do not need to, nor are you able to, add the additional parallel equipment to the system through the "Select Equipment" command. When you look at your system browser, it will show flows that also are a bit confusing, as your parent piece of equipment will show the entire flow of the system and not the flow multiplied by the flow factor. This is just how the system browser works, as it is simply summing the flows of all the parts of the system. Lower in the hierarchy will be the parallel pieces of equipment (as well as any other devices in the system) and until you properly connect your system, the flows of the parallel pieces will show as zero or n/a. Once properly connected, it will populate with the correct flow. If you inspect your properly connected system you'll see that even though your system browser shows your parent piece of equipment with the entire flow of the system on it, that the flow has been multiplied by the flow factor.
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Steve_Stafford
Posts: 224
Registered: ‎08-16-2007
Message 2 of 6 (312 Views)

Re: How do you select equipment for parallel systems?

01-31-2014 10:10 AM in reply to: RJServoss

When you select a family and create a system Revit thinks of this system as a child in search of a parent. The equipment you assign to that system is the parent. If you consider air terminals, you select one,create a supply system, and select equipment. The air terminal is the child and the equipment (VAV) is the parent. In your case the air handlers are both parents who are looking for children. Revit doesn't create systems in that order or direction. It is always looking up to a parent.

Is there a piece of equipment above them? If so then that is the equipment the air handlers can be associated with. If not then the Plenum is the child and it needs to be associated with its parents, the two air handlers.

My other older self here: http://forums.autodesk.com/t5/user/viewprofilepage/user-id/46056
Contributor
RJServoss
Posts: 16
Registered: ‎07-14-2011
Message 3 of 6 (302 Views)

Re: How do you select equipment for parallel systems?

01-31-2014 10:45 AM in reply to: Steve_Stafford
How do I assign 2 pieces of equipment as the parents?
Mentor
Steve_Stafford
Posts: 224
Registered: ‎08-16-2007
Message 4 of 6 (296 Views)

Re: How do you select equipment for parallel systems?

01-31-2014 12:25 PM in reply to: RJServoss

Do you have a component that you can select that represents the plenum return? Something needs to represent that so it can be used to create a system and then the equipment can be added to the system.

My other older self here: http://forums.autodesk.com/t5/user/viewprofilepage/user-id/46056
Valued Contributor
ajax05k
Posts: 59
Registered: ‎01-12-2014
Message 5 of 6 (227 Views)

Re: How do you select equipment for parallel systems?

02-04-2014 11:23 PM in reply to: Steve_Stafford
same problem with chillers, there are multipel chillers various AHU, and i cannot add these chillers to a single system, is there any way to group these chillers and include them in the same system.
Ajay K. HVAC Designer, BIM Modeler
Contributor
RJServoss
Posts: 16
Registered: ‎07-14-2011
Message 6 of 6 (205 Views)

Re: How do you select equipment for parallel systems?

02-07-2014 08:13 AM in reply to: ajax05k
It's a bit confusing as you would think that since the equipment is in parallel that in the system browser they would be at the same location in the hierarchy, but that is not the case. If you simply add the other piece of equipment to the system through the "edit system" "add to system" command, your system flow configuration and your flow factors will work correctly. You do not need to, nor are you able to, add the additional parallel equipment to the system through the "Select Equipment" command. When you look at your system browser, it will show flows that also are a bit confusing, as your parent piece of equipment will show the entire flow of the system and not the flow multiplied by the flow factor. This is just how the system browser works, as it is simply summing the flows of all the parts of the system. Lower in the hierarchy will be the parallel pieces of equipment (as well as any other devices in the system) and until you properly connect your system, the flows of the parallel pieces will show as zero or n/a. Once properly connected, it will populate with the correct flow. If you inspect your properly connected system you'll see that even though your system browser shows your parent piece of equipment with the entire flow of the system on it, that the flow has been multiplied by the flow factor.
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