"Watts" the Real Story about Submersible Operating Cost?

09/10/2007

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Homeowners today often ask about product energy efficiency, and submersible water systems are no exception. Your customers look to you for this assessment, and that is why it is important to properly evaluate the power requirements of the submersible motor you are installing.

The operating cost to the homeowner for a particular motor is calculated using power consumption (in watts) of the motor. Some motor manufacturers may advertise efficiency claims based on amp loads, but this is misleading because there is more to efficiency than just amp draw. Anyone claiming that lower amps automatically translates to lower operating costs is not telling the whole story. Homeowners pay for kilowatt-hours, not amps.

If you are choosing a motor based on amp draw, make sure you understand what that means. What may seem to be a competitive advantage could turn out to be a disadvantage when the right numbers are used.

Follow these steps when calculating the cost of operating a submersible motor:

• Determine the Service Factor (S.F.) Watts for the motor model to be installed (this can be found in the AIM manual for Franklin Electric motors)
• Divide this number by 1,000 to get Kilowatts
• Multiply this number by the hours of operation per day to get Kilowatt Hours (KwH) - (assume 2 Hrs. for a typical residential system)
• Check the latest electric bill to get cost per KwH (usually @ $0.10/KwH)
• Multiply this cost by the KwH value to get daily cost to operate
• Multiply this number by 365 to get an annual cost to operate

So let’s look at a real-world example where amps look good, but true power consumption tells a different story. For a ½ Hp, 2-Wire, 230 Volt submersible motor, compare the Franklin Electric motor to the competition:

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When the calculation is performed correctly, using Kilowatt Hours (KwH) instead of amps, the Franklin Electric motors consume fewer watts (10% less!), offering the lowest energy cost savings.

See also Franklin AID vol. 24, No. 4, January/February 2007