Variable-Speed Pumps: Head Of The Class

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It's pretty unusual to hear pool builders raving about pumps instead of cursing them, but recent developments in variable-speed motors for swimming pool pumps have some early adopters convinced they have come face-to-face with the future.

Whether it's been motivated by heightened safety concerns, the California Energy Commission's looming energy efficiency regulations, or just the innate human desire to build a better mousetrap, innovations in the design of pool pumps are giving builders options like they've never seen before. Radical energy savings, enhanced safety, longer pump life, reduced noise and increased water quality are just a few of the benefits of the next generation of pool pumps.

Variable-speed motors have been around for a while, but the pool and spa market has only recently discovered their benefits. Leading the variable-speed way are two companies: a small California manufacturer, Ikeric, headed up by Ike Hornsby, who began marketing his variable-speed pumps about two years ago; and the category giant Pentair, which recently introduced its IntelliFlo line of pumps.

The concept behind the variable-speed pump is deceptively simple: configure a motor that does the least amount of work necessary to get the job done. With the Ikeric pump, the installer has to figure out where that efficiency point is, as with a conventional pump. With the IntelliFlo, a complex digital component calculates the system parameters and adjusts its energy draw and work output accordingly. The installer simply enters the desired flow and the computer figures the operating point on that particular, unique system that will achieve it.

Conventional electric motors are built to run at a specific speed that is determined by the motor's anatomy and governed by the current it receives. In the past, builders had to change other parts of the equation to fit the pump, but now the pump can adjust to fit the system and the situation.

"The problem people had in the past is they'd put a pump on there and it would only operate at one point," says Rob Stiles, product manager for IntelliFlo. "Whatever point it intersected that system curve is where that pump would run. What the IntelliFlo does is give the user the ability to completely negotiate that system curve based on what he's working with. The pump basically has 3,050 curves, and it constantly switches between those. Every 16 milliseconds that pump looks at what it's doing and figures out if it's doing the right thing. And if its not, it renegotiates itself."

Although the IntelliFlo's components are considered a trade secret, Stiles explained a little of how the pump works. "We've come up with this slick way of measuring resistance of the impeller to figure out what the hydraulic situation is for the pump. There's no sensor at all. With speed and power, we can figure out what flow and pressure are. It's part of our patent. It does it all through digital input." Stiles says the IntelliFlo motor was designed specifically for the pump, and is similar to an electric car motor.

The Ikeric unit yields many of the same results, but is much less technologically complex and does not do the monitoring and calculations that the IntelliFlo's computer component is able to do.

"What made me think of this was conveyor belts," says Hornsby. "For years, people have been able to turn a knob and slow a conveyor belt down. So I got to thinking, 'There's a motor running that, how are they doing that?' Well, I went and found out." What Hornsby found out was that he could take a Sta-Rite pump and assemble it with a commercial variable frequency drive controller. "All this stuff has been around β€” this is old technology that I just put to use in the swimming pool industry." The Ikeric motors come with factory pre-sets of low, high and boost. Each of those presets actually has about 600 speeds, and that can be adjusted in the field to fit a given project.

The practical applications of variable speed technology have a direct effect on the builder. Perhaps the most radical difference is in energy savings. Stiles says that initial field-testing of the IntelliFlo has shown drastic energy savings: "The average that we saw β€” testing over about 50 pools β€” was as high as 90 percent. Some were higher, some were lower, but we could take an electric bill that averaged about $100 and knock it down to about $5 or $6."

The Ikeric variable-speed pump, which has been on the market for two years, shows similarly encouraging results. "The energy savings is phenomenal, says Hornsby. "The average energy savings that we've found over the last two years is 68 percent over a normal energy-efficient pump. We claim up to 90 percent, but that's a very few projects, and the average is 68 percent."

The manufacturers aren't the only ones raving about their inventions. Skip Phillips, principle of Questar in Escondido, Calif., and a co-founder of Genesis 3 Design Group, recently installed an Ikeric pump on a complex renovation project that included about 200 feet of perimeter overflow and a 12-foot vanishing edge. "Standard amperage draw on a 3-horsepower pump is about 14.5 amps. The Ikeric pump was drawing 1 amp," says Phillips. "That means that that pump can run 14 hours for the same price that it used to run one. And it's overflowing the pool. It was impossible to believe. What I felt, after I looked at this, is that I was literally seeing the future." Phillips adds that an IntelliFlo system is being shipped to his home where he plans to try it on his own pool.

The energy savings come not only from the pure efficiency of the motor, but also from the way it can be used in a given setting. Dave Anderson, a partner at Colorado Poolscapes in Glenwood Springs, Colo., often has to deal with harsh weather conditions high in the Colorado Rocky Mountains. He has installed an IntelliFlo pump on a small pool with a negative edge and a waterfall.

"We can slow it way down in the winter to save energy and we have it running so it's just putting some water over the side to circulate things," says Anderson. "Then in summer when we don't have to worry about the cold weather and all the heat loss, we'll crank it up to exactly the sound [the client] wants in the summer. So one pump can do both for us.

"It's too early to know how much money we're saving, but looking at the amp draw on it, I'm using 30 percent less power than if I'd just put the single pump in there to do circulation. I know he's going to see big savings just from the waterfall, where I'd have had to put a bigger pump on there to feed it, and that's what he'd have to live with all winter. So by dialing it way down now, between the heating savings and the direct energy savings, they're probably going to be about 80 percent over the winter."

It's the pump affinity law, a law of fluid dynamics, that yields all these energy savings. Steve O'Brien, vice president of marketing for A.O. Smith, the company that makes most of the electric motors for pool and spa industry manufacturers, explains: "The affinity rule states that the work done is proportional to the cube of the speed ratio. So even though you may have to run twice as long, it takes significantly less energy. Even though you have the pump running longer, the input power goes down fairly dramatically because less work is being done."

Running a pump longer to save energy? It seems counter intuitive, but it's true. And running the circulation system for longer time periods suggests other benefits.

"Instead of all this on-off, you could just dial in a 24-hour turnover rate and just let it run," says Anderson. "And for us, especially in the winter when freezing is such a critical issue, that's a neat thing to be able to do β€” just have the water moving all the time and still save energy. You can have it moving instead of having to heat it."

Hornsby adds, "Why waste energy and waste the consumer's money. Let them keep that money and put it in the bank. Or buy more amenities for their pools."

Phillips sees improved water quality as a benefit. "Instead of running six or eight hours a day with the associated operating costs of a standard centrifugal pump, then the pool sits stagnant for 16 to 18 hours β€” that's what typically happens β€” imagine a system that runs 24 hours a day, is almost silent, and is able to maintain its chemical balances and its water quality over the entire timeline. So not only is it quieter, costs less to run, and reduces the impact on the system, but in addition to that, the water quality is outrageous. And, for people who want to use alternative sanitizers like ozone, it's perfect, because ozone has no shelf life. Once the system shuts off, there's no sanitation. So now you're able to run an ozone system 24 hours a day, and your controller will only engage the saline system when the water quality starts to drop off."

Another characteristic that IntelliFlo and Ikeric share is a three-phase motor. Three-phase electrical service is generally only found in industrial parks, but both the IntelliFlo and the Ikeric are able to take single-phase residential power and change it into three-phase power. Single-phase power is not smoothly delivered; the actual voltage may fluctuate significantly. Three-phase power allows for a constant delivery of a given voltage. "The computer actually turns that single-phase voltage into three-phase voltage. It delivers the exact voltage that motor needs at the speed it's operating," says Stiles. "When you use a standard energy-efficient motor and hook it up to a residential circuit, it's not guaranteed to get the voltage it's rated for. If it's a 230-volt motor rated at 70 percent efficiency, and it gets 210 volts, it throws the efficiency off. If it's over 230 volts β€” same thing. It has to be right at 230 volts."

This is a big bonus for Anderson. "We have a lot of problems in some areas with low voltage or voltage fluctuations. That inverter assembly [in the IntelliFlo] actually cleans up the voltage and the motor is always getting a pure steady voltage. So theoretically this pump will last a lot longer; it's not going to be running as hot."

The constantly self-monitoring IntelliFlo delivers another type of consistency that's important to Anderson: "Even now, I've been reluctant to put filters on a lot of my water features because as the filter loads up the flow changes and my feature looks different," he says. "But with the IntelliFlo, even if my filter loads up, my water feature looks identical because the pump adjusts its speed to always give me that exact same flow. I can have my water features always look the same even if I have a filter on them."

The IntelliFlo has another benefit that's a result of its constant digital selfmonitoring. "Safety has become a big issue. It's very interesting to watch [the IntelliFlo] with a slow start up, and it actually checks to see if it has flow going or not, and if not, it shuts itself down. It essentially works as a safe pump. Especially for people with kids or a commercial operation, that's another added bonus." (It should be stressed that this function is a result of the pump's self-monitoring, not it's variable speed. A.O. Smith has come out with a line of one- and two-speed pumps with eMod, which also monitor possible line blockage.

Both Phillips and Stiles caution that while the IntelliFlo can zero in on the most efficient operating level for a given system, it's not a cure for poorly designed systems. No pump will outperform the limits of the plumbing to which it is attached. "This does not bail out the industry for bad plumbing," says Phillips. "As the rotation speed of the impeller is reduced, its ability to compensate for restrictions [aggravated by undersized pipes] is also reduced."

Phillips summarizes the enthusiasm of the leading-edge builders who have begun using the variable-speed technology: "We will not be designing any new systems that do not use these. We're going to use them on everything. Including jet pumps. It's pretty easy for me to size a jet pump, but [with variable-speed pumps] I can actually have variable jet speeds all at a reduced operating cost β€” and it's quieter. Very cool."

Says Anderson, "I think instead of evolutionary, it's revolutionary."

Safety From Sensitive Motors

A.O. Smith makes the motors for most pool pumps and a majority of spas. Whether OEM or replacement, and regardless of the pump's brand name, there's a very high probability that A.O. Smith made the motor.

"We have very high market share among OEMs in the in-ground pool market and fairly significant market share also in spas," says Steve O'Brien, vice president. So when A.O. Smith came out with its eMod-equipped line of motors, the news was far reaching.

"It's an electronic circuit board that mounts to the top of the motor that constantly monitors the input power. If there's a dramatic change to that input power, then eMod shuts the motor off," says O'Brien.

There are a number of reasons that the input power might vary, ane none of them are good. Things like the pump running dry, an under- or over-voltage situation or a full suction blockage: any of these conditions can cause the motor to burn up, and there could be even more serious consequences.

"We think that last reason is why eMod is going to have some fairly wide acceptance: as an extra layer of protection in the case of a full-body entrapment situation," says O'Brien.

When eMod senses a problem, it turns the motor off. The pump then restarts after two minutes. The eMod will run through this cycle five times before staying off. At that point, once the problem has been cleared, the pump can be recycled by switching it off and on again or by unplugging and replugging the power cord.

"The value proposition is pretty wide ranging," says O'Brien. "We're positioning eMod in the market as not only a device that will help save the motor and make the system last longer, but also to be there running in the background as an extra layer of protection above and beyond all the things that the entrapment-avoidance guidelines require for a safe pool."

A.O. Smith also plans to launch a platform of multi- and variable-speed solutions focused on energy savings and smart features for the 2008 requirements and beyond.

β€”K.P.

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