Siphon VS. Pump

Throttling a centrifugal pump does not create more heat and you can prove this with a digital thermometer, bucket of water, pump and valve. I did just that with multiple pumps and found throttling reduces flow and power consumption and reduces heat gain.

For those who enjoy reading, centrifugal pumps are all affected by what is called the "Laws of Affinity". There are many articles on the affinity law and what effects changes in speed, head, impeller diameter and other things have on centrifugal pumps.