Variable speed pool pumps are an often overlooked piece of equipment that, despite their ability to help maximize your swimming pool's energy efficiency, remains a somewhat obscure and unexplored world of possibility not just by pool owners but by pool professionals as well. I often hear variable speed pumps (or, VSPs) referred to as “relatively new” technology when in fact, has been on the market for pool owners for around twenty years. In other words, variable speed technology is not new, it is not uncommon, and there are zero reasons for your pool professional not to be well versed in VSP operation and not to be applying that sweet, sweet efficiency to your equipment arsenal. There is a lot we could say about the different makes, models, and characteristics of the many different VSPs on the market today, but for the purpose of this article, we’re just going to cover a few basic reasons why you should consider retiring that old single-speed and getting outfitted with a variable-speed pool pump.
They Save You Money-
It is no secret that variable-speed pumps can save you money. What seems to be less understood is how they save you money and how much money you can potentially save by incorporating a VSP into your equipment lineup.
It’s simple enough to imagine that when you reduce the operating speed of your filter pump, energy consumption will also be proportionally reduced, which will lead to a reduction in operating costs. You could just take that explanation on its face, but in order to really maximize the benefit of your variable speed pump, it will be helpful to have a bit more insight into what’s going on when you ramp down the rpm (rotations per minute) of your pump.
The idea of running a pump at a lower rpm in the name of energy conservation existed before the rise of variable speed. Two-speed pumps have been a relatively popular option for years. Two-speed pumps allow you to alter between 3450 rpm and 1725 rpm by flipping a switch or activating a relay. This more primitive version of “variable speed” is helpful but not nearly as efficient as a properly programmed VSP potentially can be. Besides the obvious advantage of being able to schedule more efficient operating characteristics during off-peak hours, with the variable speed, you have the ability to cater the maximum GPM (gallons per minute) necessary to operate your specific swimming pool configuration without exceeding the point of diminishing return. To use an analogy, a two-speed pump is like driving an old pickup with a 2-speed manual transmission. If the sweet spot for your particular pool is 60 GPM, and your options are 40 GPM or 100 GPM, then you will always either be suffering from diminished power (or flow) in features or functions of your pool, or you will be slamming the truck into 1st gear and running the tachometer into the red line past the point of diminishing return (I re-iterate). The resulting parasitic energy loss costs you money and puts undue wear and tear on your investment, which also costs you money. A variable speed pump is akin to a modern sedan with a 6-speed automatic transmission. You have the ability to move smoothly through any given terrain while maintaining an optimized power band which means less wasted energy, less heat and friction, and less wear on the internal components of the machine.
The relationship between the operating speed of your VSP, the pump's volume capacity (flow in gallons per minute and back pressure, commonly referred to as “head”), and the subsequent power consumption of said pump can be calculated by using the “pump affinity law.” The simplified breakdown of the Pump Affinity Law is this: when you reduce a pumps operating speed by half, the volumetric flow is also reduced by half; but the head pressure is reduced to 1/4 that of the head pressure at high speed, and the energy consumption is slashed to 1/8 that of the same pump operating at high speed. So you see, there is a dramatic increase in electrical efficiency when you reduce your pump's rpm. To use a common household metric, a filter pump running at 3450 rpm and moving 120 gallons of water per minute is consuming approximately the same amount of electricity as twenty 100-watt incandescent light bulbs. If you reduce that pump rpm by half to 1725 rpm, you get the expected 50% reduction in flow to 60 gallons per minute, but your electrical consumption plummets to an equivalent of four 100 watt light bulbs. Half that operating speed again, and you are spending about as much money to operate that pump as it would cost you to operate a single 100-watt light bulb. This can have a significant impact on your power bill every month, and as the cost of electricity steadily goes up, the benefit of a variable-speed pump becomes more and more impactful on your household budget.
When a variable speed pump is tied into a decent automation system, you have the ability to use a single pump for multiple functions and schedules, altering the pump's flow rate appropriately for each application. This saves you money upfront by reducing the number of pumps required to operate your pool's features, as well as down the road by applying your pump's efficiency characteristics to other functions outside routine circulation.
This cost savings potential alone should be enough to convince anybody that variable speed is the way to go, but let’s explore a few more benefits of VSPs that are worth considering.
They Are Quiet-
Residential swimming pools have evolved into much more than a summertime distraction for the kids. Very often, the pool is the crown jewel of your home's outdoor living area, with as many water features as functional recreation space. A seamless integration of the utilitarian function of your pool equipment and the aesthetic appeal of your aquatic space is critical to executing the most enjoyable swimming pool environment possible. A long-time approach to isolating the pool environment from the pool machinery has been to locate the equipment pad as far from the pool deck as reasonably possible and to erect a pony wall as a sound barrier for the noisy mechanical operations of the pool equipment. As population density in urban areas increases, property lines are growing ever narrower, and in the Las Vegas area particularly, suburban yards are commonly separated by concrete block walls that act like a reflecting mirror for any ruckus taking place on the side of the home. A variable speed pump can give you an edge in creating that enjoyable experience you're looking for without the ability to put much distance between you and your equipment.
They Offer Flexible Operation-
Even without an automation system, a quality variable speed pump can run at several speeds and runtime programs as a standalone piece of equipment.
When you utilize the customizable features found in automation, you can stretch a single VSP across multiple duties effectively. You can heat your spa through a footwell return at an optimum rpm for your heater to achieve the most efficient heat time and then use an automatic valve actuator with a speed change assignment to use the same pump to run your therapy jets at just the right pressure, eliminating the need for an additional spa booster pump.
You can use automatic valve actuators to divert your circulation return to one or more water features with just the right flow rate needed to make them perfect.
In colder climates that utilize the freeze protection function, you can adjust the pump operating speed during freeze activation to allow the pump to do its job without waking up your family and your neighbors. Along that same vein, you can capitalize on the off-peak energy hours we touched on above and run your pump at a very low rpm throughout the night without being a nuisance to those sleeping or stargazing within earshot.
You can achieve all of this and more throughout the day without lifting a finger, all while still saving on your power bill.
They Offer Intelligent Control-
Unless you’re specifically avoiding it, everything in our lives today is becoming “smart.” Variable speed pumps use onboard sensors to monitor operating conditions and parameters coupled with software to communicate that information with the end-user (you). Smartphones are the obvious remote control of choice these days, and every major pool equipment manufacturer has integrated their VSP operations into one or more forms of smartphone control. Aside from your standard on/off switch, app-driven pump controls allow you to monitor your equipment operating status, monitor your power consumption, and change your flow rate on the fly.
Smart pumps also have self-monitoring failsafe protections designed to shut the pump down in a condition that may cause damage to the equipment. A good example would be prime-loss, wherein the pump has lost the vacuum for one reason or another and is in danger of running dry. On the other side of that coin, if a smart pump experiences a spike in the back- the pressure that is indicative of a deadhead condition, such as a closed isolation valve, will shut down operation until the situation is resolved, preventing potentially costly repairs of damaged plumbing and equipment.
Certain automation systems allow you to monitor your equipment run-time characteristics plotted in graph form. This type of data motoring capability can be a powerful tool for the efficiency-minded pool owner, helping you to dial in rpm and run-time scheduling catered to off-peak energy usage hours.
Environmental Responsibility / DOE Compliance
This isn’t a political blog, and I have no professional opinion on which side of the environmentally-conscious fence you have planted your feet. It is clear that federal and local governmental agencies want these devices in your backyard, and the government gets what they want. Getting out ahead of stricter regulations on energy consumption makes good sense regardless of your feelings on the matter. The important thing to note here is that whether you are interested in variable speed pumps because you believe them to be a component in your overall effort to reduce your energy consumption in the name of environmental responsibility or not if you own a pool, federal and local regulations mean you are going to own a variable speed pool pump at some point in your future if you don’t already. It is technically true that there are single-speed pumps that meet current efficiency requirements, but those allowances cover an increasingly shrinking minority of motor types. When it comes to investing money into your pool equipment, a little foresight goes a long way in preventing you from throwing good money after bad. As we like to say around here: buy once, cry once. Yes, variable-speed pumps are considerably more expensive than their single and two-speed counterparts, but as we have discussed throughout this article, a properly utilized VSP has significant potential to save you money over time. If you make the effort to educate yourself and set it up properly, a variable speed pump will eventually provide a return on your investment as well as lessen your personal environmental impact on your community, win win. To sweeten the deal, many utility companies offer rebates for installing variable-speed pumps.
The inevitable truth is, these pumps are the future of the pool industry. Go with the (variable) flow; because resistance is not only futile, it’s costing you money.