Variable-speed pumps have come a long way, just ask Ben Honadel.
Five years ago, when a homeowner called his company to enquire about the product, a representative would explain its benefits. The customer would either make the purchase then, or say they wanted to discuss it with their service technician.
“That’s when we’d run into trouble,” explains Honadel, owner of Pools by Ben in Santa Clarita, Calif. “Either we wouldn’t hear from the homeowner again, or they’d call and say, ‘The pool man told me they’re no good, they’re too expensive, and they don’t save money. Why are you trying to sell snake oil?’”
Flash forward to today, and the pumps have evolved, along with attitudes about them. Models are entering the market that don’t require a specific manufacturer’s controller, or any controller at all, making it easier to fit them into existing circulation systems. And professionals are finding that not only do variable-speed pumps save energy, but they can result in cleaner, quieter pools, and help builders create custom features.
Here, installers who’ve come in from the ground floor discuss how to maximize the benefits of today’s variable-speed pumps.
The big picture
Today, when working with a new pool or extensive renovation that involves replumbing, builders can gain as much as 70 percent energy savings with a VSP.
But many builders and service techs don’t install or program the products to deliver the maximum benefits.
On existing pools, there is less flexibility. Builders must set a maximum pump speed to correlate with the plumbing capacity.
But for new pools and replumbs, the system should be designed with the least head pressure so the water can run on low speeds. This also can accommodate the pump at its full 3,450 rmps, should it ever be ramped up to the maximum.
Benefits of VSPs also include programming. The key is to run the pump on the lowest speeds possible for long periods of time. And if local utilities charge higher rates to run at peak hours, the pumps also should be set up to operate at their highest speeds during off-hours, when possible.
The most energy savings and cleanest water result from running the pumps all day.
This is especially appealing when installing corona discharge ozone systems. Since this technology doesn’t leave a residual, they’re best to run 24 hours a day so the water is continually sanitized. But even when using chlorine, it helps to move the water all day because the chemicals are constantly being mixed. “So you don’t have issues where, when the pump shuts off, everything sits stagnant and the pH drops, and in the deep end the pH changes,” Honadel says.
The bulk of the day, the water should run on a very low speed. This mixes the water, but also is extremely economical. “If we’re running at 600 rpm at 24 hours a day, our kilowatt costs would be $8 per month,” says Barry Justus, president of Poolscape Inc. in Burlington, Ontario, Canada.
Still, the water must run faster than that for a while in order for proper skimming, and for chemical feeders and automatic cleaners to do their job. So program the unit to run at somewhat higher rates — for Justice, that means approximately 2,500 rpms — for as many hours as necessary to meet turnover requirements.
“The most common program we do is 22 hours slow and two hours at a skim speed,” Honadel says. “Skim speed is the time where the pool behaves like it did before [variable-speed pumps were used]. It’s fast enough to skim the pool, to run an automatic pool cleaner, to heat the pool if you want the heater to turn on, and for a spa spillway or waterfeature to spill over.”
Ideally, set up the pump to do this at night, particularly in areas where it costs more to run at peak hours. If the system is plumbed correctly, the pump shouldn’t make enough noise to disturb homeowners while they’re sleeping, these professionals say.
Consult with the customer about when they want the pool and its features to run. “People have very specific needs and wants,” says Marc Del Chiaro, service department manager for Geremia Pools, a Pool & Spa News Top Builder in Sacramento, Calif. “Some have it come on four times a day for two hours on low speed, then they want their cleaner running in the middle of the night. Some like to sit outside in the morning, so they want the spillover action from the spa into the pool during that time. Some people want to be out there and watch their cleaner as it’s working.”
Variable-speed pumps may be programmed to offer custom operation.
For instance, they can be set up so that vanishing edges and perimeter-overflow pools run as efficiently as possible while still sending enough water over the rim. “The tolerances are very tight, and our goal is to keep the rpms down as low as possible — just enough to wet the edge in order to save energy,” Justus says.
He, for one, programs the pump so that when the vanishing-edge system turns on, it runs at a higher rate for a few minutes — just long enough to raise the water level, break the meniscus and begin to spill. Then the rate goes down, so there’s just enough water to wet the edge.
“Typically we’ll start the pump at around 2,600 to 2,800 rpm, then the edge will generally run at 1,000 to 1,400 rpm,” Justus says. “I have less water going down the edge, the pump is a lot quieter, and there are substantial energy savings.”
He also uses the technology to simplify the plumbing of wet walls. Because these waterfeatures usually don’t require the flow generated by even the smallest single-speed pump, builders in the past would restrict flow with valves or divert extra water with a blow-off line. “Now, with the variable-drive, all you do is gate back the rpms on the pump and get the exact flow,” Justus says.
VSPs also can be used to operate larger rock waterfeatures on different modes, from low to voluminous flows.
Justus further uses the pumps to offer customized spa jet options. One of his clients was recovering from a shoulder injury and wanted a variety of jet flows to help. Justice tried a 3-horsepower pump. “But that was too strong — it was hurting his shoulder,” Justus says. “We switched to a variable drive. We programmed it with three different settings, and he’ll choose one depending on how his shoulder feels that day.” Builders can do the same for those who prefer different outputs.
Justus even uses the pumps to help minimize the effects of the freezing Canadian winters. Rather than close pools, he can run them at about 600 rpm to keep the water moving. “The relatively warm water from the bottom of the pool gets sent up to the surface and the water doesn’t freeze up nearly as much so there won’t be a build-up,” Justus says. It costs hardly anything to run, he adds, and especially helps minimize damage to all-tile pools and waterfeatures.
When adding a variable-speed pump to an existing pool, installers have to work with the plumbing that’s there. (Click here for a plumbing schematic on a raised spa project using variable-speed pumps.)
But on new vessels, builders can truly get the most out these products. The trick is to generate the necessary flow while running at the lowest speeds. This requires large plumbing.
“You shouldn’t plumb a pool with a variable-speed pump the same way you plumb with an oversized 2-hp induction motor,” says Steve Toth, owner of Acclaim Pools in The Woodlands, Texas.
Experts have long recommended a balanced loop for plumbing spa jets and pool inlets, but with variable-speed pumps, this kind of schematic is crucial.
No more compensating for differential pressure by placing smaller inlets close to the pump and using larger ones farther away. That may work with a 2-hp pump, where there’s enough energy to overcome head pressure in the system and send enough water to each inlet, Toth says. “But if you’re trying to circulate a pool with ½ hp or ¾ hp, and instead of having 13 feet of velocity per second you only have about 2, you don’t have any wasted head pressure.”
If you’re running a pump at the equivalent of ½- or ¾-hp, the plumbing should be larger and configured in a hydraulically balanced loop. Otherwise, most of the water will move through the returns closest to the pump, with little to nothing coming out of the remaining inlets. “So you’ll wind up with a dirty pool,” Toth says.
The rules for minimizing turbulence become even more important on these installations. For instance, installers who have continued to use hard 90-degree elbows should finally convert over to sweep 90s, or use two 45s instead.
Without the right plumbing, not only are energy savings lost, but the unit’s quiet operation is compromised as well. To illustrate, Toth tells of the next-door neighbor to one of his clients.
“My client’s pool has a 1-hp pump on it, and even though it’s an induction motor, I can’t hear it. Instead, all I hear is the variable-speed motor over the fence, blaring away at 3,450 rpms, because the pool was never plumbed correctly.”
Other adjustments must be made to compensate for the loss in pressure: “You have to create head pressure in order to force water up into a raised spa or waterfeature,” Toth explains. He accomplishes this by placing a two-way valve on the pool return side so he can adjust the flow into the spa.
“We’ll choke it down a little bit, create a little head pressure that heads out toward the pool to force more up into the raised spa,” he says.