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Darrell D
January 31, 2014, 11:45 AM
My model runs fairly well, but bogs down and fails when I put on demand multipliers above 1.5. In investigating the issue, I have found that my pumps are operating at a point 10psi lower than the pressure indicated at the nearest downstream node which is the trigger for their operation. So when the second pump is to come on, it is already outside of its operating range. Any insight into this issue would be appreciated

Thanks, D

Shawn Huang
January 31, 2014, 12:54 PM
More detailed information is needed: (1) are the pumps VSP? (2) do the two pumps operate with the same control?

Darrell D
January 31, 2014, 01:12 PM
Hi Shawn,

Sorry. They are not VSPs. They both operate based on remote junction pressure which is the first junction after each pump. They are not controlled by the same junction. The first one is on/off at 68/73 and the second is 60/70. Please let me know if more information will help.

Thanks, D

Shawn Huang
January 31, 2014, 01:29 PM
It might be an unbalanced error. What is your maximum trials? Did you see any warning/error message about these two pumps? If so, I would like to take a look.

Darrell D
February 3, 2014, 07:51 AM
It is an unbalanced error. Maximum trials are set at 40. There are not warnings about the two pumps specifically, but those keep turning on and off during the trials. I sent a message to your inbox.

Darrell D
February 21, 2014, 01:41 PM
I resolved the issue by adding a hydro-tank. Thanks for your assistance.

Shawn Huang
February 21, 2014, 01:44 PM
thanks for the update! The hydro-tank will stabilize the numerical simulation a lot.