Your Complete Guide to Variable Speed Pool Pumps

Single speed and dual speed pool pumps are officially a thing of the past. More and more pool owners are ditching the noisy, inefficient pumps that were once the norm and upgrading to far superior variable speed pool pumps. Since your pool pump can be the largest electricity consumer in your home, trading your old single speed pump for a more efficient variable speed pool pump can make a huge difference in your energy bill. But without the proper knowledge of how to set your pool pump correctly, some pool owners may be missing out on some of the biggest benefits that come from upgrading.

3 Types of Pool Pumps

Pool pumps have improved dramatically since they were first developed, and selecting the right one can be one of the best investments you can make as a pool owner. Here are the three top types of pool pumps on the market today:

1. Single Speed Pool Pumps

The original style of a pool pump, and also the least expensive, is the single speed pump. These always operate at the full rated horsepower speed which is 3450 RPM, and the speed cannot be adjusted. Since they only have one speed, they generally run at higher speeds than most pools need. They are the least efficient of the three kinds of pool pump available.

2. Dual Speed Pool Pumps

Dual speed pool pumps have a high speed and a low speed setting. They are more efficient than single speed pumps and have a higher upfront cost. However, you will not get maximum efficiency from a dual speed pump because they cannot be fine-tuned to specific flow rates.

3. Variable Speed Pool Pumps

By far the best option when it comes to pool pumps, variable speed pumps are much quieter than single or dual speed pumps and allow for a full range of speeds to easily fine-tune flow rates. They have the highest upfront cost of the three options but will save you money in the long run with lower operational costs.

Why You Need a Variable Speed Pool Pump

More Efficient Motor

Variable speed pool pumps are essential to operating a healthy pool for a variety of reasons. They are powered by a different motor than single and dual speed pumps, known as a permanent magnetic motor. The same type of motor used in electric cars, it is much more efficient than the induction motors used in traditional single and dual speed pool pumps. These motors use permanent magnets to create a magnetic field between the rotor and the windings. The improved efficiency is due to the magnets working to spin the rotor, as opposed to standard induction motors that require additional electricity to induce the magnetic field into the rotor. Permanent magnetic motors have efficiency ratings of 90 percent while the average single speed pool pump will only achieve efficiency ratings between 30 percent and 70 percent. This means that running a variable speed pool pump will consume a significantly less amount of energy with the same flow rate as a single speed pump.

Less Power Consumption

Although variable speed pool pumps have a higher upfront cost, they will end up recovering all of that cost and saving you even more money over time. This is because variable speed pool pumps allow you to run your pool at a lower speed for a longer period of time, as opposed to single speed pumps that run at higher speeds for a shorter period of time. Single speed pool pumps typically run at a much higher speed than necessary, which means they are constantly wasting energy. Reducing the speed of your pool pump causes a disproportionate decrease in energy consumption - so even the slightest decrease in your pump's speed can save you a significant amount of money. Since variable speed pool pumps have more efficient motors and allow you to set the speed to exactly what your pool needs and no more, they will save you the most on your energy bill compared to any other pool pump.

Better Pool Circulation

Due to the high energy costs and loud operating noise, most pool owners who use a single speed pump end up running them for eight hours a day or less. This means that for most of the day their pool water is sitting stagnant and building up bacteria and other contaminants. With more contaminant build up, pools will require more chlorine and, in turn, more toxic chloramines that cause irritation and chlorine smell will be created. In some cases, pool owners with single speed pumps only run them at night to help lower electric costs. This is even worse because their pool water sits stagnant during the day when the sun is out which leaves the sun's UV rays to degrade the pool's chlorine. On the other hand, you can run a variable speed pool pump a longer period of time, ideally 24 hours per day, with lower energy costs and without the obnoxiously loud sound you'd get with a single speed pool pump. This will create better circulation in your pool, leading to a much healthier pool that requires fewer chemicals. Any supplemental sanitation such as AOP, UV, or ozone systems will also perform much better with continuous circulation, making it possible to lower chlorine levels to that of drinking water chlorine levels or less.

Less Pool Pump Noise

Single speed pool pumps can be very loud, making it even more impractical to leave them running overnight. Because variable speed pumps are much quieter, it is possible to leave them running 24/7 at a lower speed without keeping your family or your neighbors up all night.

Better Pool Filtration

Running a pool pump at too high of speed can lower the effectiveness of your filter. By running a variable speed pump at a lower speed for a longer period of time you can allow your filter to work more effectively, leaving you with a cleaner pool and preserving the life of your filter.

Rebates

The energy-saving benefits of a variable speed pool pump can even qualify you for utility rebates through your power company. If you take advantage of these incentives, the cost of a variable speed pool pump could end up being comparable or lower to the cost of a dual speed pump.

Avoid Fines

Some states may have energy efficiency laws that restrict the use of higher horsepower single speed pool pumps, forcing you to invest in a more efficient pump. Consult with a pool professional to find out if your pool pump is in compliance with your state’s laws.

How Much Can a Variable Speed Pool Pump Save You?

One important thing to understand about how pool pumps work is that running your pump at lower speeds for longer periods of time will cost much less than running it at high speeds for shorter periods of time. It might seem like if you run a pool pump at half the speed for twice the amount of time, the energy consumption would even out. However, because of a principle known as the Pump Affinity Law, the energy savings grow disproportionately larger the more you lower the speed of your pool pump. According to this principle, if you reduce your pump speed by 30 percent you will see a 70 percent reduction in power consumption. When you lower the motor speed by half, power consumption is reduced to one-eighth of the original draw. For example, let’s say it costs $2.20 a day to run your single speed pool pump for 8 hours - then it will only cost one-eighth, or $0.28, of that to run a variable speed pool pump at half of the same speed for 8 hours. If you run the variable speed pool pump for 24 hours for maximum circulation, it will still only cost $0.84. That is an energy savings of 62 percent while running your pool pump three times as long. Even if you are running your variable speed pool pump 24 hours a day, as long as you optimize the flow rate according to your pool’s features and run it at an efficient speed, you will be able to cut back significantly on your energy bill. Depending on factors like the state you live in and your pool size, you could save upwards of $500 per year in electricity.

How Long to Run Your Variable Speed Pool Pump

When people upgrade from a single speed pool pump to a variable speed pool pump they often continue to run their pump from eight to 10 hours a day, just as they did with their single speed pump. However, it is important to note that a variable speed pool pump should ideally be running 24 hours a day to ensure proper and optimal water circulation. When your pool pump is not running, the water is sitting stagnant in your pool allowing bacteria to survive and grow. Additionally, any method of water disinfection you use is not able to work properly when your water is not circulating. This can lead to health hazards because even if you turn the pool pump off only when you are not using the pool, once you turn the pump back on it will take some time before that stagnant water is fully disinfected. While running your pool pump 24 hours a day may subtract from some of the energy savings you gain by switching to a variable speed pool pump, it will be worth doing in order to have peace of mind that your pool water is healthy.

The Importance of Pool Water Circulation

One key factor in maintaining a healthy pool - that is often overlooked by pool operators - is the importance of pool circulation and "turnover rate." Your pool's turnover rate refers to the number of times the entire volume of the water is circulated in a 24-hour period. According to the Gage-Bidwell Law of Dilution, water that is recirculated with a turnover rate equal to one turnover in each 6 to 8 hour period will provide 95 to 98 percent dilution of contaminated pool water with water that has been filtered and disinfected. Three to four turnovers per day, or one turnover every 6 to 8 hours, has become a standard in public pools and is highly recommended in residential pool owners who want a healthy pool that doesn't require large quantities of chemical disinfectants. For example, AOP systems make it possible to drastically reduce chlorine use to drinking water levels of 0.5 ppm or less in residential pools, but this requires the use of variable speed pool pumps running at an optimized flow rate 24 hours a day and with a minimum of three turnovers per day. For those who are used to running their pool pump for only 8 or 10 hours a day, it may seem counterintuitive or wasteful to run your variable speed pump 24 hours a day. But remember that running your variable speed pump for a longer period of time is still much cheaper and more effective than running a single speed pump for a short period of time. By optimizing your pool pump’s flow rate according to your pools needs, and running the pump 24 hours a day during the pool season, you can ensure your pool is clear, healthy, and ready to go at all times.

How to Calculate the Proper Flow Rate for Your Pool

In order to optimize your variable speed pool pump for your pool, you must determine the flow rate your pool needs for adequate circulation. It is important to remember that variable speed pool pumps are not really about varying the speeds, but rather about finding the optimum speed for the pool. First, find out the number of gallons of water your pool can hold. Then, divide this number by the desired turnover rate, ideally 6 to 8 hours. Then, divide that answer by 60 to find the minimum flow rate in GPM, or gallons per minute. For example, if your pool has a capacity of 24,000 gallons, and you want a turnover rate of 8 hours or three turnovers per day, then you will need a minimum flow rate of about 50 GPM. The maximum flow rate for your pool depends on the size of your plumbing. For 2 inch pipes, the maximum flow into the pool pump will be 73 GPM. For 1.5 inch pipes, the maximum flow into the pump will be 42 GPM. Make sure to consult with a pool professional when determining the proper flow rate for your pool.

A Good Investment

The higher upfront cost of buying a variable speed pool pump may prevent some people from making the investment, but in the long run, it will cost far less than running an inefficient pool pump. Taking advantage of rebates and incentives can help you recover some of that upfront cost as well, making it even more economical. Combine this with the fact that variable speed pool pumps are better for the environment and better for your pool, and it’s a no-brainer.