Save Money, With This Inverter Variable Speed Mod to Your Pool Pump




There are commercially available units which use an VFD inverter to vary the speed of your pool pump, and although they provide great savings, being a DIY-er i wanted to have a go on my own, and try and simplify the whole unit.

I highly recommend checking out the commercial product from FUTURE WAVE, which can be purchased and applied to almost any pool pump for a large saving.

The parts list for this project is quite simple:
      1 x VFD with built in Programmable controller
      1 x 1m power lead

If you get the exact unit i got, you can use the settings included here.

Step 1: Wiring and Programming

Firstly source your VFD.

I purchased this one from EBAY for a very reasonable price, high quality, good waranty.

When it arrives, undo the packaging.and read the instructions to find the best method to hook up. I intended to install this for my parents, so i wanted to make it as simple to use as possible. I decided to use the inbuilt PLC operation to cycle through the modes, so there was nothing for them to adjust.

Connect up your power to the input terminals. Use an electrician to to this, mains wiring is dangerous! I used an extension cord, chopped in half, so i could plug the male end in where the pump was connected, and plug the pump into the female end. This will be different if you have a hard wired pump.

The first thing is to make the VFD start when it gets power ( as standard, they wait for a start signal ).

With this inverter you need to change
PD001, SOURCE OF RUN COMMAND, to 1 ( External ) and
PD044, Function for FOR input, to Run ( default is Forward direction, not used unless you also use reverse ),

Then bridge the FOR terminal to the DCM terminal ( as though you are continuously holding the run button ).

Thats the control wiring sorted

Other internal control changes:
PD007    change to 50 hz for MAIN speed, This is the default frequency that the inverter starts at ( we use 50 hz power in Australia )
PD080    change to 1 for 16 internal speed control
PD081    change to 1 for cycling run ( it cycles through the speeds you set and starts again when it gets to the end )
PD084    change to 3 sec ( ramp time when changing speeds )
PD086    change to 35hz ( our set SLOW SPEED. you can go slower if your pool still allows leaves to go back to the pickup )
PD101    change to 240 sec ( 4 minutes ). This is the time it runs at the MAIN speed
PD101    change to 6300 sec ( 1 hour 45 minutes ). This is the time running at SLOW SPEED. Maximum setting is 6500 sec

There are usually settings that need to be specified based on the exact motor you have. They are usually read off the metal plate on the motor.

The cycle with the above setup is:

Power on, ramp up to 50 hz, run at 50hz for 4 minutes, ramp down to 35 hz, run at 35 hz for 1 hour 45 minutes, ramp up to 50 hz, run at 50hz for 4 minutes.....etc

If power is interrupted, the cycle starts at the beginning again.

Step 2: Results of Operation $$$$$ SAVING!

I was surprised at the reduction in output current that resulted from running at 35hz.

Motor plugged into the wall 4.6 amps
Motor power at 35Hz 1.5 amps !!!!
Motor and inverter plugged into the wall 6.6 amps ( holy crap this inverter is wasting heaps of power )
Motor and inverter plugged in running at 35Hz, 3.5 amps

So the inverter is using an additional 2 amps! im a bit disappointed by this, and im going to look into why this is happening.
It could be that this inverter although is specified to run from single phase or 3 phase, is simply not efficient when running on single phase.

Never the less, it is still using much less power than it was, and this 1 amp, or 240 watts adds up.
at 20c / kWh, with the pump running 10hrs per day, its 50c/day saving. All up the inverter cost $120, so will pay back in 8 months
After 2 years the saving is $230.

Importantly, if i can work out why the damn inverter is wasting a couple of amps and prevent it, it will save 3 amps, or 750 watts. this means the savings are more than $500 per year and the payback is 3 months!

Either way it was an interesting experience!

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    10 Discussions


    2 years ago

    This is an old ible, but I'm looking at the same thing myself so thanks for posting.

    I do have a few questions now that you've had this running a while:

    1. did you figure out the 2A loss on the VFD

    2. did you modify the pump from single phase by removing the start capacitor to 3 phase using the U,V, & W outputs of the VFD direct to the motor windings

    3. has using the VFD caused any negative impact on the life of your pump


    2 years ago

    thanks for sharing your experience, do you have any experience or know links to control the VFD invertors by Arduino module


    4 years ago on Introduction

    I installed a VFD on my pool in 2010. At the same time, I installed a 3 phase motor. This configuration allows me to run my pump several times per day at a reduced speed and has saved me considerable electrical expense. The main reason for installation was for anti-freeze capabilities. I typically don't close my pool in the winter (NC, USA). The temps here can get down into the teens at night, but day times are usually above freezing. With this setup and my home automation controlling my pool pump, I can run the pump at a trickle when temps are below 36'ish degrees. Worked like a charm for 3 winters, last fall I got lax with a clogged line. Combine that with a VERY cold winter and my pool plumbing splintered above ground. I was forced to winterize my pool mid- winter while I had the flue in 10 degree weather. Was quite a mess. Still haven't totally gotten my plumbing back to normal yet.

    Moral of the story; be careful.

    I've replaced one VFD and motor (non-TEFC) so the cost to maintain can increase depending on your situation.

    My system performed as designed, I just became lax. The energy savings can be realized, but this system does add operational overhead. If you have the budget, purchase a variable speed pump system and be done with it.



    5 years ago on Step 2

    Having tried this I have noted that most VSDs that are designed for 3 phase in and 3 phase out do not have enought capacitors after the 3 phase bridge rectifier to maitain a smooth DC to the inverter stage. That is because the ripple on rectified 3 phase is naturally very small anyway where-as single phase drops to zero volts between each half cycle. This means the next half cycle has to charge up the capacitors much more. It also makes the current waveform on the mains much more "peaky". Depending on the quality of your meter you are using it may not be giving you the correct reading either.

    The bottom line is that the meter on your switchboard reads the apparent power not real power so the more non sinewave the power is the more money you pay for it no mater what your test meter reads.

    The easy fix is to add more capacitance across the rectifier and the problem goes away.It works well.

    It even works if you have a single phase supply and a 3 phase motor.




    6 years ago on Introduction

    Sorry, I didn't get to page 2 of your instructions and read your wasted power concerns. My slant on the wasted power is that it is being wasted by having to convert from single phase (versus split phase here in USA) direct to 3-phase. I f you had 3-phase available your consumption would be more in line, but conversion "costs" about 33% more, due to having to lead-lag the current in the motor, which has to be invented, so to speak. But as I understand it, your mains there are single phase the same as ours would be if the neutral was to be disconnected from the ground circuit, which are bound in residential consumers here in the states. Our 240 here is down graded to 208/220 kinda like, since it can flux greatly just due to your neighbor on the same transformer. State side takes each leg of the 240 (which is not RMS value) and equal, and splits it with the neutral to get 2 legs of 120 volts each, then recombines them to get 208 volts, thus losing 33% of power already purchased! All by evil design, I'm sure. Anyway, even if you put a 3-phase convertor in front of your VFC, you would still lose 1/3 of your power, (by design!) to save your VFC the same function it now performs. A static inverter wouldn't help either, you would just lose Hertz/speed control and have to use a timed circuit, but the start up would not be soft, as you have it set up now. Cheers, John from Florida.


    6 years ago on Introduction

    Thanks Wayne for the info. I have been looking at Huanyang and others for a VFC for a 240 volt 3-phase conversion for my sailboat. The info here in the states is very limited and hardly anyone knows about this kind of circuitry around here. Yours is the first comment I've found about programming and usage, even though I bet very few even know what you are talking about on here, I found it quite informative. I am also looking at a unit that has a "knob" control pot in conjunction with the touch pad. My question I ask is do you know if the power consumption is any less at 1/2, 3/4 power or is the power linear and the VFC causes the motor to act more on the lines of a ICE for it's torque curve with no Amperage change? I can't find this info from the inverter specs. Any info is greatly appreciated. John from Florida


    7 years ago on Introduction

    Have to agree with pfred, I've owned pools for decades, I run mine about 2 hours a night unless the autovac needs more time and that's a 30' round pool. Occasionally after heavy use and chemical dose I let it circulate longer. It's a cool idea and nicely thought out "ible" but personally I feel that going larger than needed with my pump and filter and circulating all the water in a couple hours has saved me a bundle over the years

    2 replies

    Reply 7 years ago on Introduction

    This is on a salt water pool, and unless it is run, it does not turn the salt into chlorine. Also, running the pump filters the floating debris off the surface so it does not sink to the bottom reducing the need to vacuum. There is already a timer on the pool pump.


    7 years ago on Introduction

    Why don't you just put a timer onto your pool pump and shut it off for as long as you can?