Ill-conditioned

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Paulo Praça

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Dec 28, 2014, 2:24:58 PM12/28/14

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I' m working on a network, and always get this error message: System ill-conditioned at node 99198; reservoir FR3 is closed; reservoir FR1 is closed; Tank R_Vc is closed at 4.30m. I'm stuck, any ideas will be appreciated.

Thanks,
Paulo Praça

Patrick Moore

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Nov 24, 2015, 11:54:19 AM11/24/15

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An ill conditioned node warning means that EPANET has no reference head to solve the hydraulic equations in a particular area of the model. This occurs when are area has no path back to a Tank or Reservoir. This can often happen when a Tank goes 100% or 0% full as it will close off the tank in the EPANET solver. If this is the only Tank or Reservoir it can have a path to it can't solve the equations.

Generally if you find which tank is having issues and find what is causing that you will usually fix the problem.