Using variable speed pool pump with SWG

[Rockman59]

Update: I am still running my VS Pentair pump 10 hours a day....7 hours at 1750rpm and 3 hours at 2750rpm. My Intelchlor 40 SWG is pumping out plenty of chlorine running at 60%. I am considering cutting back on the pump runtime to save even more energy. With the VS pump I am now down about 40% from the energy useage of the single speed pump I used to have. Comments?

[mas985]

Why so high on the RPM levels? I thought you were going to reduce those.

I would target 1000 RPM for the lower speed and 2000 RPM for the higher speed and only for 1-2 hours.

[Rockman59]

Mas985 said: Why so high on the RPM levels?...................The rpm levels were programmed by the installer...he works for a very reputable long-established pool company and seems to know his business. Since I had no experience with VS pumps I went along with his suggestion of 7 hours at low rpms and 3 hours of faster rpms. I cut back to 6 hours of low rpm a few days ago and will be monitoring the water quality. My IC-40 chlorine generator is now set at 60% and still producing plenty. I started with it at 100%. As I mentioned I will be keeping a close eye on the pool. I also use a Pool Shark and it works well at the 2750 rpm setting....much slower at the 1750 rpm setting. My pool is a large one (48 feet, 40K gallons) so the Pool Shark has a lot of pebble tec to clean and I'm not sure it can get the job done at the 2000 rpm setting.

[Rockman59]

Got my first electric bill since the VS pump was installed a month ago. Useage down almost 50% from a year ago...same number of days in billing cycle, WX conditions also about the same. Amazing.

[Motoman]

I don't understand why some think variable speed motors are not worth the investment.

[PoolDoc]

1. They are far less reliable than a 2-speed pump, especially in areas with thunderstorms (and lighting related power surges). They probably should not be installed in lightning prone areas, like Florida

2. Failures in the electronic motor control are common, usually not covered by warranty, with a cost of repair of 70% or more of the cost of a new pump.

3. Electrical savings, over what a 2 speed pump provides, are significant, but marginally so.

4. Initial pump cost is almost double what a 2-speed pump + timer costs, so much of the electrical savings is consumed paying for that cost difference.

[Motoman]

1. They are far less reliable than a 2-speed pump, especially in areas with thunderstorms (and lighting related power surges). They probably should not be installed in lightning prone areas, like Florida

First, I am new to the site and very new at pools, but i do have a pretty good bit of knowledge on motors, mechanics and physics. I'm enjoying the great education I'm getting by reading the many professional posts. I would love to share some of the knowledge from my field.

With that said, A Metal Oxide Varistor or MOV, can be wired in parallel to each of the line voltage legs to ground, and they are only a couple bucks from Radio Shack. Or you can install a surge protection device to the disconnect box, Home Depot $20

2. Failures in the electronic motor control are common, usually not covered by warranty, with a cost of repair of 70% or more of the cost of a new pump.

most failure in the commutator are caused by surges or brownouts. This causes the NTC thermistor protection device to fail (a very inexpensive repair for an electronic hobbyist). MOV's will take care of this, sacrificing itself before taking out the internal protector. I have yet to tear apart my new Hayward VS pump, but can't imagine it is much different than other ECM motors I have experience with.
Another protection device on VS motors are power chokes. Basically an inductor wired in series with the line input to slow the input current and reduce the harmonics cause by the square wave form. These need to be appropriately sized.

3. Electrical savings, over what a 2 speed pump provides, are significant, but marginally so.

Though residential meters don't allow for a higher apparent power cost doesn't mean we don't pay in other ways. As we continue to build more houses an continue to use poor power factor split phase AC motors, this requires the power company to increase power production and increase the supply line service cables far beyond the what would be needed from more electrically efficient equipment. This is seen in the annual or biannual rate increase for all. For those "GREEN" people, it means a larger carbon footprint.

4. Initial pump cost is almost double what a 2-speed pump + timer costs, so much of the electrical savings is consumed paying for that cost difference.

If the motor and module are properly loaded and protected, these motors will provide years of energy savings. Paying for the difference in less than 2 years when comparing to the cost of an inefficient split phase motor.

Hope I haven't overstepped by greenhorn status.

[Rockman59]

IC 40 still producing plenty of chlorine so I backed it down today to 40% output. Correction: In the above post I said my electric bill was down 50% from a year ago which I attributed to the new VS pump....actually it is down 35%...which I think is still pretty good.