Changing transient solver accuracy and max trials

Product(s): HAMMER
Version(s): 10.XX.XX.XX, and greater
Area:  Calculation


How can you change the Accuracy and Maximum Trials for the transient calculation engine?

Transient results appear to be unstable, though all data input appears to be correct and reasonable. Can anything be adjusted to help with convergence of the transient simulation?

How to resolve the following error?

Error 45527 : "Maximum number of iterations 100 is exceeded in constant-speed pump. Check input data."

Problem ID#: 52285


By default, the accuracy and trials for the transient engine are hard coded at Trials = 40 and Accuracy = 0.001

Starting with the V8i SELECTseries 2 release (, in extreme cases, you can enter special text into the notes of the transient calculation options to be able to change the max trial and accuracy. In the "Notes" field of the transient calculation options for the scenario in question, enter the following text:


This will tell HAMMER to use the "accuracy" and "trials" fields from the Steady State/EPS calculation options (the one set to the scenario in question), for the transient accuracy and trials. So, in cases where the calculation engine fails due to non-convergence, you can use this special option, then either increase the maximum trials or accuracy value in the Steady State/EPS calculation options.

See Also