No flow coming out of pump when I have the pump set on and FCV active

Question

I have the pump target flow set at 1000 gpm and FCV set as active with 500 gpm for the initial flow. Not sure why there is no flow coming out of the pump when running the model. I am trying to understand what could cause the issue? The model is balanced but I have a warning message indicating FCV cannot deliver flow.

Scott Kampa · Answer

Hello Michael, 
 Are there any user notifications related to the pump? This link may have some information that can be useful. 
 Are there controls on the pump? Where is the FCV relative to the pump? It may be useful to see a copy of the model files as well. 
 Regards, 
 Scott

Scott Kampa · Answer

Hello Michael, 
 The VSPB is initially off. If you set the VSPB to be initially on, there will be flow through the VSPB and the FCV. It looks like there is no control on the VSPB, so if the VSPB is initially off, it will stay off through the run. You can add controls, but it can be a little tricky with variable speed pumps. There is information in the Help documentation about this. 
 The FCV is initially set as Inactive, which means that the FCV is fully open through the run. Given the placement of the FCV, this may be as expected. Otherwise you have a flow of 1000 gpm and immediately drop that to 500 gpm. 
 Regards, 
 Scott

Scott Kampa · Answer

Hello Michael, 
 The active scenario in the model was different from the one seen in the screenshots. In the scenario from your screenshots, the VSPB and the FCV are on and active. 
 In that scenario, the flow from the VSPB is zero and there is a user notification that says the the VSPB cannot deliver head and flow. I believe that part of the issue is that the VSPB and FCV settings are not compatible. 
 Is there a reason that the VSPB has a setting of 1000 gpm and the FCV has a setting of 500 gpm? There is no demand between them. It appears that the FCV setting so much lower than the VSPB settings is causing the issue. As a quick test, I set the initial status of the FCV to "Inactive" and there was flow through the VSPB that matched the setting. 
 Regards, 
 Scott

Scott Kampa · Answer

Hello Michael, 
 Is Berkeley FCV-34 a real FCV in the system? If so, does it really drop the flow from 1000 gpm at the pump to 500 gpm? 
 If I set the VSPB to have a fixed flow of 500 gpm, the VSPB operates correctly, the system is not unbalanced, and the St Catherine Booster pump appears to operate at less than the maximum operating point. 
 If that is not a valid setup, more information on how this is expected to be set may be needed. For instance, what should the flow be from the VSPB in question? 
 Regards, 
 Scott

Jesse Dringoli · Answer

As a supplement to this conversation, and to echo Scott's concerns about the purpose of the FCV, please see the following article and blog post link: 
 Using a Flow Control Valve 
 Death to Flow Control Valves

Scott Kampa · Answer

Hello Michael, 
 Part of the issue may be related to instabilities related to the placement of the FCV directly downstream of the VSPB. You can try adjusting some of the calculation options, like Damping Limit, to see if there is any improvement. 
 But is there an FCV at this point in the model? It seems odd that there would be an FCV that would drop the flow by half just downstream of a pump whose purpose is to generate a given amount of flow. 
 If the FCV is not in the system, what is it supposed to represent? 
 Regards, 
 Scott