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Topic: Re: Why does our new pump have a lower flow rate?

posed by 
Your new 2 pole speed pump obviously has a much steeper curve than the older 4 pole speed pump.Your new piping on the discharge is causing more friction losses in a system that has significant friction losses already.
This would result in a higher head and lower flow. I suggest you fit a 2 x 3 increaser on the discharge of the new pump and refit all the rest to the existing 3-inch line.