Super Pump Motor Replacement Cost Analysis

[pondfishr]

I live in Tennessee with relatively low utility rate of 9.368 cents per Kilowatt hour. Unless I need to replace my single speed super pump motor due to motor failure it really doesn't make financial sense to purchase even a 2 speed motor much less ever purchase a brand new variable speed pump for $700.00 plus. If I want to be green and help the environment that is another story. Then one could factor in the energy and resources required to build a new motor to replace a working motor. Ok enough of that.

My theory is figured on 6 hours of pump run time per day single speed vs dual speed. Your mileage will vary depending on your run time and your residential electricity rate per kilowatt hour.

A standard 1 hp super pump 56J replacement motor at Electric Motor Warehouse motor draws around 7.5 Amps at 220 V. 7.5 x 220 = 1.650 kilowatts per hour x 6 = 9.900 kilowatts per day. My electricity rate is 9.368 cents per kilowatt hour. 9.368 cents per hour x 9.9 = 93 cents per day x 30 = $27.90 per month running the pump 6 hours per day.


Take the Electric Motor Warehouse Century STS1102RV1 two speed Super Pump replacement motor. According to EMW specs on high the current draw 8.5 Amps and is 2.5 Amps at low speed.

Compared running on high 2 hours per day / on low for 4 hours per day.

8.5A on high x 220V = 1.870 kilowatts per hour
2.5A on low x 220V = .550 kilowatts per hour.

Running 2 hours on high 1.870 kilowatts x 2 = 3.74 kilowatts per day on high.
Running 4 hours on low .55 kilowatts x 4 hours = 2.2 kilowatts per day on low.
3.74 + 2.2 = 5.94 kilowatts per day with a 2 speed motor
5.94 kilowatts x 9.368 cents per kilowatt hour = 56 cents per day to run a two speed motor for 2 hours on high and 4 hours on low.
56 cents per day x 30 days = $16.80 per month.

Total savings of the two speed motor = $27.90 - $16.80= $11.10 per month.

If you are replacing the 56J style motor only -
Single Speed non energy efficient motor model 1102 cost is $156.00.
Dual Speed energy efficient motor model STS1102RV1 cost is $274.00
$274 - $156 = $118.00 dollars difference in the price or 10.6 months running at 30 days per month to recoup the investment.
The point is for me when my motor breaks I will look into a dual speed but most likely not before. I also will need to add the cost of a $150.00 Intermatic 2 Speed digital timer to replace the single speed mechanical timer I have today.

Sorry if I bored you with this post but I started typing and couldn't stop!!

 

[Isaac-1]

What you say does seem to add up, but you should be aware of one other advantage of switching to a 2 speed motor, they are much quieter when running on low speed. This can be an important factor if the constant drone of the pump running on high bothers you.

 

[pooldv]

You probably won't need to run on high 2 hours per day, just when vacuuming or backwashing. More like an hour per week.

Here, I'll add another monkey to the wrench. My 3hpVS pump runs my skimmers and SWG at 1100 rpm which draws 150 watts. You could avoid the cost of a timer and get this Pentair SuperFlo VS Pump 342001 | Pentair 342001 pump for <700 bucks.

 

[pondfishr]

Your comments concerning the Pentair 342001 ability to run at such a low RPM are enticing. I am a little concerned about the risk of the SWG becoming energized from the mechanical controller when the integrated timer on the pump has the pump shut down? Or are you saying the SWG be connected directly to the Super Flo VS timer output?

 

[pooldv]

No, my pump is wired directly to the breaker and my SWG is wired to its own timer. I usually only run my SWG 6-8 hours at most. My pump runs 12-24 hours. I do make sure that the SWG run time is inside the pump run time window. Although the flow sensor shuts the SWG down if the pump isn't on for some reason.

 

[JamesW]

Some variable speed motors now include a auxiliary load control relay for things like a booster pump or swg. At least one of the Jandy flopro models has this. At least one of the Century V-Green replacement motors has this. For the flopro, the relay closes once the rpm is at least 1725. You run one leg of the power through the relay to make sure that the auxiliary equipment does not operate when the variable speed pump is off.