[Equest-users] UA Convergence Error

[Paul Diglio]

Bill, David, Jeff and Nick:
Thank you for the responses.
I am using 3.65 Build 7175.  I am not using the refrigeration mode, as far as I know.  The only two modes shown under Select Version are 2.2 and 2.3.  I am using 2.3.  Doesn't the refrigeration version have an R after the DOE version?

I am not using a waterside economizer.  I have 2 air handlers per building.  One feeds the north all three floors and one feeds the south all three floors.  They are VAV units with a chilled water loop and an electric reheat coil for each building.  Each building has 2 chillers for the loop and one pump.  The VAV boxes do not have reheat capability.

Perhaps the oddest thing is that this project is in Saudi Arabia and I am using the TMY2/RIYADH83.bin weather file.
The error message I am getting is:
***ERROR***********************************************************************
Heat-Exchanger: EA Sys1 A-1 (VAVS) (G) UA calculation
failed to converge.
The EA Sys A-1 in the above error message changes.  Sometimes I increase the number of ACH/Hr for a few zones in building A and I get an error message for EB System B-2 (building B) or EC System C1 (Building C).  Can't make rhyme or reason of connection. 

Many thanks,

Paul Diglio
87 Fairmont Avenue 
New Haven, CT 06513 

203-415-0082 

    On Monday, December 9, 2019, 5:27:53 PM EST, Jeff Hirsch <james.j.hirsch at gmail.com> wrote:  
 
 That message seems to indicate you are using the refrigeration version (2.2R) ... for a conventional building model you should use 2.3 or 2.2 not 2.2R ... in the refrigeration version coils use a heat exchanger model, so you probably have many heat exchangers. But, again, perhaps you should be using 2.3. Jeff Hirsch
James J. Hirsch & Associates
voice mail: (805) 553-9000
mobile: (805) 532-1045


 From: Paul Diglio via Equest-users Sent: Monday, December 9, 2019 3:13 AMTo: Equest-users Subject: [Equest-users] UA Convergence Error Hi Folks: I am getting a "heat exchanger XX Sys1 UA calculation failed to converge" error.  The model has three building in it and only two air handlers per building.  I don't have any heat exchangers attached to the air handlers or any heat recovery installed.
 Sometimes the error occurs when I change the glass type via the library and other times I get the error when I adjust the air changes per hour in one or two zones. In the example above, the error was for system B2, but it varies...sometimes systems A or C 1 or 2. Any ideas what the problem could be?  
 Thank you,
 Paul Diglio
87 Fairmont Avenue 
New Haven, CT 06513 




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