Using variable speed pool pump with SWG

[Rockman59]

I am considering converting to a variable speed pump. The vendor says I will save a lot of money my electric bill. They want to program the pump to run 7 hours a day at 1750 rpm and 3 hours a day at 2750 rpm. Now the question....is this enough time at the 2750 speed for my Intelichlor IC-40 SWG to make enough chlorine for my pool? I currently have a one speed pump that runs 8 hours a day at 3450 rpm and does the job. I am concerned that 3 hours a day at the 2750 speed and 7 hours at the 1750 setting will not produce enough chlorine for my 40,000 gallon pool. Comments please. And thank you in advance.

[mas985]

Pump speed has almost nothing to do with chlorine production as long as the minimum flow rate requirements are met. If 8 hours is enough for your old pump, 8 hours should be enough for your new pump. But the vendor's schedule is a little overkill in my book. 1-2 hours at 2500 and 7-6 hours at 1000 RPM should be enough run time (8 hour total). Most VS pumps have peak efficiency around 1000 RPM so I would target most of the run time around that.

[Rockman59]

mas985.....thanks for the info.

[Rockman59]

Currently running the variable speed pump at 7 hours at 1750 and 3 hours at 2750 and the IC 40 is making plenty of chlorine. I am considering cutting back to 7 hours at 1000rpm and 2 hours at 2500 rpm. I live in the SoCal desert where right now the highs are in the mid 90s which eats up the chlorine. Any comments?

[mas985]

Sounds reasonable. You may find that you can cut back even further.

[CarlD]

Interesting. Not familiar with VS pumps (only 2spd pumps). My SWCG can actually be wired to control the pump and the pump speeds, but I keep it simple, personally.

[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.

[PoolDoc]

Motoman, it sounds like you may know how to *improve* the VS pumps on the market today, but that doesn't mean that the pumps currently available to pool owners have those improvements.

The fact that sacrificial lightning protection *could* be installed on those pumps is nice. But the relevant question is, has it been installed? I doubt it, since I haven't seen in replaceable "lighting protection modules" in the parts lists of any of the VS pumps I've looked at.

Varistors have been used in surge protection for as long as I've been around computers . . . and while they can stop ordinary power surges, they don't seem to stop lightning based surges. In California, an MOV may be adequate protection (and probably is already present), but it doesn't seem to be adequate in Florida or Louisiana. If there were adequate cautions with the pumps, warning of the risks of installing them in lightning prone areas -- fine. But the pool industry is back at its normal practice of selling the new gizmo to EVERYBODY, regardless of whether it's appropriate for them.

The whole "my pump is GREENER than your pump" pitch is unpersuasive to me. If you can point to clearly organized and well sourced data validating this, I'm willing to change my mind. But I'm sick to death of "green" alternatives that turn out -- like corn based methanol -- to be anything but 'green'. For God's sake, people in S. America went hungry by the 1,000's because of that particular debacle -- and US citizens are still paying MORE for gas that is LESS efficient and that apparently has a negative net energy gain!

I'm all for energy efficiency: the savings are real, when everyone drives a car that gets 30 MPG instead of 15 MPG -- or replaces a single speed pump with a 2-speed. But I don't think we need any more "Solyndra" projects, which wasted a half billion of taxpayer money OR hokey pool 'green' gadgets which waste an individual pool owner's money.

Your savings factors seem to be comparing VS pumps to single speed pumps . . . which I did NOT do. I've been advocating the use of highly reliable 2-speed pumps for years, and the data I've seen suggests that the savings of VS pumps compared to properly installed 2-speed pumps is small. I will concede that it's easier for the typical pool builder to install the one-size-fits-all VS pump correctly, than it is to size a 2-speed pump.

I don't doubt that the industrial VS controllers for non-fractional motors have the features you describe. But they don't seem to be present, or at least, don't seem to be effective on the VS pumps pool owners are buying.

I'm not opposed to VS pumps; I'm just opposed to the somewhat deceptive and hyped marketing that pool owners are being subjected to.

[Motoman]

Once I'm up and running, I will be happy to log some data and share it.

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Oh yeah, looking at the pump, one more protection that could be added is a heat shield to protect the module. Because of the module location they are prone to heat stress.

[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.