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I would like to know if and how I could have my pool pump motor consume less energy. It is a 1 HP motor that works on 220v. It is my assumption that if the motor runs slower, then it will consume less energy, such as a fan with different settings for the fan speed. Does anyone know how to easily do this?

The volume of water that the pool really needs is a lot less than what is coming out and less gallons per minute through the pool pump that feeds the pool would not effect the final outcome which is to recirculate the water.

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  • \$\begingroup\$ From what I understand, in Arizona you can't even legally install a full-speed circulation pump anymore. If the pump drives the filter, then it must be able to run at low speed. Apparently you can still use high-speed pumps for other things like running water jets and such. \$\endgroup\$ – tylerl Mar 28 '12 at 5:37
  • \$\begingroup\$ You can't "use less electricity". Electricity is not a quantity, it's a physical phenomenon. What you mean is "use less power (or energy)". \$\endgroup\$ – stevenvh Mar 28 '12 at 13:30
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Speed control of single phase induction motors can be achieved by driving them at different frequencies - more complex and expensive than is usually appropriate, or by changing drive to the main winding or start winding.

Many examples and discussions are available on web.


Driving whole motor:

Microcontroller driving while motor with TRIACs.
Freescale An3471 - Ceiling Fan Speed Control - Single-Phase Motor Speed Control Using MC9RS08KA
Relatively simple. I'm somewhat surprised that they say you can achieve good results this simply. Freescale SHOULD know what they are doing. Need not use a microcontroller.
Here U1 is an optical controlled TRIAC which is used to trigger the larger TRIAC Q1.

enter image description here


Shaded pole motor control with PIC - You tube


Separate out windings:

New method for speed control of single phase induction motor with improved motor performance
Abstract only but very useful.
Diagram thumbnails small but useful.

  • Abstract

    In this paper, a new method of speed control for the single phase induction motor is introduced to overcome the disadvantages of the conventional methods. In this method, the magnitude of the main winding current and its angle are controlled to control the motor speed, as well as to increase the starting torque at all speed settings. In the meanwhile, the voltage applied to the auxiliary winding is kept constant at the rated value. The performance of a 1 hp capacitor run single phase induction motor is experimentally and theoretically investigated, using this method of speed control. The experimental rig is built in the laboratory and a complete set of test results is obtained. On the other hand, a mathematical model for the motor is developed and the motor performance is calculated. Good agreement between the experimental and theoretical results is obtained. These results show that the new method of speed control gives much higher starting torque. This enables the motor to start at low speed settings. Also, a great improvement in motor efficiency and power factor at all speeds is achieved.

3 methods - diagrams dead
Some value


Variable frequency:

[Microchip AN984 - An introduction to AC Induction Motor Control using the dsPIC30F MCU]

Student project
Appears competent.

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Russell has already given you a direct answer to your question, but here is another possibility. The point is to save overall electricity since you don't need the flow rate of the pump at full speed.

Another way to achieve this is to turn the pump on and off periodically. There will be a current surge and therefore some inefficiency each time the pump is turned on, so you don't want to do this every few seconds. This also allows you get down to average flow rates that would be impractical by reducing the pump speed. The pool is a large reservoir relative to even the full flow rate of your pump, so will naturally average out pulses of full flow.

Try running it for 2 minutes every 5 minutes and see how that works. That can be accomplished very simply by a microcontroller driving a relay thru a transistor. This will allow you to tune the average on percentage by adjusting the off period. Due to the startup effeciency, I'd probably stick to 2 minute on times and adjust the off times. For example, if you can get away with 2 minutes on every 10 minutes the electric consumption will be close to 20% of the steady on case.

 

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  • \$\begingroup\$ Wouldn't this be bad for the pump motor & start/run capacitor? \$\endgroup\$ – peter_mcc May 1 '12 at 14:07
  • \$\begingroup\$ @peter: It shouldn't be much extra stress if it is turned on and off only once every 5 minutes or so. \$\endgroup\$ – Olin Lathrop May 1 '12 at 14:49
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the pump has a job to do so the size of it is important and the amount of time it is run and the motor must have good bearings,clean filter. I find most pumps are way too big for the job but can be re-sized easily .. ask your local pool pump motor whats the cheapest way to run your pump and how best to take care of it.. I hear all the time "why doesn't anybody tell me that, thanks man" want cheap ? ? I built a solar pump that I got 42 gallons a minute. thats free

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  • \$\begingroup\$ Well, these answers are interesting. But, I feel that there is a huge market for an inexpensive homeowner installable device that can reduce the huge electric bill that is created by a pool pump motor. My best friend works for a national chain of pool supply stores and he says that he can get this "product" on the shelf. Does anybody know of a board that can be easily installed as an add on to a typical pool pump timer that would reduce electric consumption, either by cycling 2 minutes on, 5 minutes off or something more sophisticated that is already being produced and can be remarketed ? \$\endgroup\$ – Andrew Mar 29 '12 at 2:42
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    \$\begingroup\$ @Andrew: yes. such devices exist. they're called Time switches ... \$\endgroup\$ – Stefan Paul Noack Apr 16 '12 at 12:36
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Answer: For given voltage the motor consumes less power when rotates faster

The non-electrical solution can be modifying the loaded part of the pump. Say chop off few leafs off the fan. It will reduce the torque, increase the velocity, increase the counter-EMF and reduce the consumed current. Ideally zero torque can be achieved when motor rotates with maximum speed consuming zero power.

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    \$\begingroup\$ Most pumps use centrifugal impellers which lose almost all suction if you remove blades. \$\endgroup\$ – Cybergibbons May 27 '12 at 19:34
  • \$\begingroup\$ Yes. This is the point exactly \$\endgroup\$ – user924 May 27 '12 at 19:37
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    \$\begingroup\$ We're not talking 50% suction though, we're talking almost nothing, and it is very difficult to adjust. You are much better to either narrow the blades or drill holes in the impeller to increase bypass. \$\endgroup\$ – Cybergibbons May 27 '12 at 19:46
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Since a centrifugal pump motor is least loaded at shut-off simply closing the outlet valve reduces the load and the power consumed. Do not fully close the valve as this will overheat the pump due to recirculation within it.

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