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