Wouldn't a Cycle Stop Valve use more energy?

[Cosmacelf]

In an old thread here (https://terrylove.com/forums/index.php?threads/submersible-pumps-and-multiple-check-valves.26301/), Valveman recommended using a Cycle Stop Valve to reduce water hammer.

It seems to me that a Cycle Stop Valve increases head pressure. Wouldn't that increase total energy usage, over say, a Variable Frequency Drive without a CSV?

 

[LLigetfa]

When head pressure increases, GPM decreases and so too does the amps drawn. The amount of decrease depends on the pump design whether the impellers float on individual bearings or carried by the motor bearings.

 

[Sponsor]

 

[Valveman]

In an old thread here (https://terrylove.com/forums/index.php?threads/submersible-pumps-and-multiple-check-valves.26301/), Valveman recommended using a Cycle Stop Valve to reduce water hammer.

It seems to me that a Cycle Stop Valve increases head pressure. Wouldn't that increase total energy usage, over say, a Variable Frequency Drive without a CSV?

Yeah I have to answer that question 10 times a day. It is completely counter intuitive, but restricting the flow with a valve will decrease amps or energy consumption almost the same as reducing the rpm with a VFD. And to confuse you even more, the lower the flow rate produced, the more energy per gallon a VFD system will use.

A 5HP, 100 GPM pump will use about 20 amps of current. Slow that pump down with a VFD, and yes it will only be drawing maybe 10 amps. However, it will only be producing about 10 GPM at 10 amps. So a VFD will use 500% more energy to pump water.

 

[LLigetfa]

The anti-CSV, VFD proponents love to use the analogy that the CSV is like driving with one foot on the gas pedal and the other foot on the brake pedal. It is a terrible (and false) analogy but when they cannot win the argument with facts they resort to FUD. Unfortunately it is unintuitive enough that many believe it.