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Variable Speed Pool Pumps

Scope

Variable-speed pump with low head loss filter and piping layout
Variable-speed pump with low head loss filter and piping layout

Install a single- or two-speed pool pump with a variable-speed pump while minimizing head pressure from system piping and filter.

  • Program the pump to obtain adequate circulation at the lowest possible motor speed.
  • Provide for seasonal or water feature flow adjustments where necessary.

See the Compliance Tab for related codes and standards requirements,

Description

Pool pumps provide an important function for in-ground pools by circulating water through the pool’s filtration system. The filtration system keeps the water clean, clear, and sanitary for bathers by screening debris that falls into the pool and also removing algae and microorganisms that can pose potential health threats to swimmers. In addition, pumps may circulate water through heaters, cleaners (also known as sweeps), water features, or fountains. These single-speed pumps traditionally have a 1- or 2-horsepower motor that will run at least five to six hours per day, if not around the clock, consuming energy.

A variable-speed pool pump can reduce pool pump energy use by 50% to 90%. The majority of the savings is derived from a variable-speed pump’s ability to reduce the rpm of the motor, thus reducing energy use. A typical 1½-horsepower (hp) pool pump draws about 2,000 watts and runs at 3,450 revolutions per minute (rpm). Reducing the pump speed and flow has a tremendous impact on wattage draw due to the Pump Affinity Law. For example, if you reduce the pump speed from 3,450 rpm to 2,400 rpm (30% reduction in speed) the wattage drops from 2,000 watts to 593 watts (70% reduction in power).

The primary reason that most single-speed pool pumps consume an excessive amount of electricity is that they are typically oversized and overused in the course of pool operation. A pool pump is called upon to perform multiple water circulation duties during the operation of the pool. While the primary function of the pool pump is to simply circulate water through the filtration system, other tasks can include powering spa jets, backwashing the filter, operating a chlorinator, providing water for the pool sweeper, circulating water through the heater, initiating flow to a solar panel and pumping water to waterfalls and other water features (Figure 1). These occasional tasks require more energy (a greater flow rate) than the circulation of pool water through the filtration system and account for roughly 10% of the pool pump’s operation time. Often, pools have multiple pumps to provide some of the functions listed above (Figure 2).

Pool pumps perform many functions in a swimming pool including circulating water through the filtration system and heater, backwashing the filter, operating a chlorinator, providing water for the pool sweeper, etc.
Figure 1. Pool pumps perform many functions in a swimming pool including circulating water through the filtration system, powering spa jets, backwashing the filter, operating a chlorinator, providing water for the pool sweeper, circulating water through the heater, initiating flow to a solar panel, and pumping water to waterfalls and other water features (image courtesy of Steve Easley Associates).

Variable-speed pool pumps can cut energy use by 50% to 90% compared to standard single-speed pumps.
Figure 2. Variable-speed pool pumps can cut energy use by 50% to 90% compared to standard single-speed pumps (image courtesy of Steve Easley Associates).

Single-speed pumps by design can’t change their flow rate so they must be sized to perform the most demanding task. This means that during 90% of the operational time, single-speed pool pumps provide greater circulation than the pool filtration system requires. A standard pool pump is typically 1½ to 2 hp and operates using a single-speed induction motor generating excessive filtration flow rates. At a pump speed of 3,450 rpm, between 1,500 and 2,500 watts of electricity are required depending on the service factor of the motor.

Although not common, two-speed pool pumps may be encountered. Two-speed pumps have been available for years and are marketed as an alternative to more expensive variable-speed pumps. The two-speed pump uses an induction motor and is basically two motors in one with a standard 3,450 rpm (full-speed) motor and a 1,725 rpm (half-speed) option. Ideally these motors may enable significant energy savings for the homeowner; however, if the half-speed motor is unable to complete the required water circulation task, the larger motor will operate exclusively. Because there are only two speed choices, it is much more difficult to fine-tune the flow rates required for maximum energy savings.

A variable-speed pool pump will allow the homeowner to achieve the ideal filtration flow rate with the least amount of energy consumption. Variable-speed pumps utilize permanent magnet motors (PMM), which use permanent magnets to create a magnetic field between the rotor and the windings. This configuration is similar to the motors used in hybrid cars. Efficiencies are gained by the magnets working to spin the rotor, as opposed to a standard induction motor that requires additional electricity to induce the magnetic field into the rotor. The PMM motor design is much more energy efficient when compared to the standard induction motor, achieving efficiency ratings of 90% while the average single-speed pump will have efficiency ratings between 30% and 80%. PMM pumps can produce the same gpm flow rate as single-speed induction motors if needed; they simply run much more efficiently.

The largest energy savings of installing a PMM pump comes from the ability to program and reduce the flow rate to match the required pumping task. Unlike a single-speed pump that will operate at a maximum flow rate even for tasks that require minimum flow rates, the variable-speed pump can be slowed down to the optimum level, balancing flow rate needs with energy use.

How to Install a Variable-Speed Pool Pump

  1. Inspecting the Pool Area: The health and safety of the pool pump installer, as well as the occupants, should be a critical part of the pool pump replacement process. Prior to beginning pump installation, the installer should carefully inspect the entire pool area for exposed wiring, trip hazards, pests, or animals. A thorough inspection of the pool pump containment area and any exposed plumbing should also be done to ensure that any leaks or damage to existing pool plumbing are identified and repaired. Finally, the installer should locate the main electrical circuit breaker panel and identify and confirm which breaker is designated for the pool pump.
     
  2. Measuring the Pool and Calculating Pool Volume: There are two important reasons why an installer must accurately calculate the volume (in gallons) of water in the pool. First, the pool pump must have the correct flow rate (volume of water that passes through the pump) in order to meet the proper turnover rate and maintain clarity and sanitary conditions in the pool. The pump must have the capability to turn over the entire volume of water within a 12-hour period, although the 12-hour turnover is not typically required for daily filtering and sanitizing. A turnover every 24 hours is the minimum needed filtration flow rate for the pool pump. If the pool’s entire volume of water is not turned over within a 24-hour period, the risk of algae and pathogens can increase. To calculate the minimum flow rate of the pool pump, divide the total volume of the pool in gallons by 1,440 (total minutes in a day).

    Total volume of pool / 1440 = Minimum Filtration Flow Rate (gpm)

    The minimum filtration flow rate is the least amount of water (gpm) the pool pump must circulate through the filtration system in order to achieve the minimum daily turnover.

    The second reason for calculating the pool volume is to determine the maximum pool filtration rate. The pool pump should not have a filtration rate greater than the rate needed to turn over the pool water volume in six hours, or 36 gallons per minute (gpm), whichever is greater. This equation was developed by the California Energy Commission and was adopted by the Association of Pool and Spa Professionals to help set guidelines for achieving the maximum energy efficiency in pool pump operation. To calculate the maximum filtration flow rate, divide the total volume of water in the pool by 360.

    Total volume of pool /360 = Maximum Filtration Flow Rate (gpm)

    For pools with less than 13,000 gallons, the pump must have a gpm rating of 36 gpm or less.

    Because pools come in countless designs, shapes, and depths, calculating pool volume is rarely simple. In order to calculate oblong, circular, sloped, nonlinear sloped, and custom pool designs, more advanced mathematical calculations are required. Use the ENERGY STAR pool pump calculator.

    Once the total pool volume in gallons has been determined, the installer can calculate the maximum and minimum filtration rates. This information will help calibrate the new pool pump to make sure it is operating at peak performance from both a health and energy efficiency standpoint.
     

  3. Remove an Existing Pool Pump (if there is one; see the Retrofit tab).
    A reciprocating saw works well to cut PVC pipe during pool pump installation
    Figure 3. A reciprocating saw works well to cut PVC pipe during pool pump installation.

  4. Connecting Fittings and Making Electrical Connections: After all fittings and connections have been made, reconnect the electrical conduit and wires per national, state, and local codes. Also, ensure the ground bonding wire is connected to the pump’s bonding lug (Figure 4).
    Make sure the ground bonding wire is securely fastened to the pump’s bonding lug
    Figure 4. Make sure the ground bonding wire is securely fastened to the pump’s bonding lug.

    Most existing single-speed pumps are electrically powered through a timer or automation system to schedule their daily operation. Newer variable-speed pumps have the time clock and scheduling feature inherent in their control system. For these pumps, it is preferable to wire them directly, bypassing the existing time clock. For installations with remotely operated automation systems, the pump may be controlled through relays. This is done to ensure that the pump has a continuous uninterrupted power supply.
     

  5. Calibrating Variable-Speed Pump for Optimum Performance: After installation is complete, the installer must program the new pump to obtain adequate filtration, in-pool circulation, sanitation, and water clarity while using the lowest possible motor speed.

    Filters only capture what is suspended in the water passing through them and only what is large enough to collect on the filter media. Once debris and sediment enters the pool water, one of three things will happen: it will float, sink, or get suspended in the water. Floating matter can be skimmed off the surface, but once it sinks to the pool floor, it will stay there without some kind of help to remove it. Variable-speed pumps need to run longer to accomplish the required turnover due to their lower flow rates. As a result, the pool spends much more time skimming the water and preventing debris from sinking. The result is a cleaner pool with improved water clarity, which is another benefit derived from running pumps at a slower rate and for longer periods of time.

    The variable-speed pump should be set up to operate at a speed that will turn over the pool volume at least once during every 24-hour period. For pools with high debris and/or bather loads, additional turnovers may be required to maintain adequate water quality. In no event should the turnover time be less than six-hours during normal operation.

    Reducing the flow through main drains by throttling the drain’s return line valve (if applicable) can improve skimmer performance by providing the pump with most, or all of the water from the skimmer. However, this configuration must be tested to confirm the pump is supplied with enough water when operating the pump at the highest speed needed by the pool. This is often not the highest speed at which a pump can operate and should only be high enough to achieve the intended purpose, such as operating cleaner therapy jets, or a water feature. Essentially, the goal is always to provide sanitation and to accomplish operation of any water features at the lowest flow rate. The start-up flow rate may need to be higher for several minutes to fully prime the pump, purge air from the filter, and fill solar panels with water. Once these start-up tasks have been completed, the pump speed can be reduced to the energy-efficient low-speed setting.

    Pools sometimes need higher turnover flow rates, for example, following a storm or pool party. It is advantageous to have this feature set up in advance to provide the pool owner with a mode that will temporarily override the normal filtration flow rate without the need for reprogramming the pump controller.
     

  6. Verification and Filtration Flow Rate Testing: Always follow the pump manufacturer’s instructions and guidelines, especially the warning and safety instructions. The instructions listed here are not intended to be comprehensive and are not a substitute for adherence to the manufacturer’s instructions.

    During the removal and installation process, air can enter the system and become pressurized. Excessive pressure can result in an explosion of the filter housing. Before system start-up, the pump and system must be manually primed and evacuated of air. Care should be taken to vent system air through the filter’s manual relief valve.

    Caution: do not run the pump dry. To prime, remove the strainer pot lid and fill the pump with water until the level reaches the suction port, and then replace the strainer pot lid. This prevents the pump from running dry, which will damage the mechanical seal. Start by opening the manual relief valve on top of the filter and then press the button to start the pump. Next, you must bleed air from the filter until a steady stream of water comes out, and then close the manual air relief valve.

    Remember, the basic premise of variable speed energy-saving pump operation is “run it slower and run it longer.” By running the pump slower, a slight reduction in water flow (gpm) will greatly reduce the electrical demand (kW). By reducing the flow rate, runtime will have to increase to ensure that the water is adequately filtered and mixed.

    After the pump has been started and is successfully circulating water through the filtration system, filtration flow rates need to be verified. Water is supplied to the pump from both the skimmers and main drains; however, the skimmers should supply the majority of the flow. Minimum filtration flow rates need to ensure that the skimmers function adequately. Most skimmers take approximately 25 gallons per minute (GPM) of flow for adequate performance. Verification of performance can usually be accomplished by visually observing surface water drawn into the skimmer face and over the weir door. Skimmer baskets need to be checked and cleaned regularly. Main drain flow should complement the skimmer flow but should be minimized to prevent suction entrapment hazards. The main drain and suction covers should be visually observed and verified to be VGB 2008 compliant. A noncompliant, broken, or missing drain cover poses a serious health risk and should be replaced immediately, even before the pool is returned to service.
     

  7. Programmable Pumps and Maintenance: Note that some variable-speed pumps may be capable of producing a maximum flow rate higher than the existing single-speed pump. Excessive flow rates can present hazards such as suction entrapment. Use caution when installing and programming to limit a pump’s performance potential with old or questionable equipment and to avoid suction entrapment hazards.

    Many variable-speed pumps have the ability to schedule features throughout the day. As such, the pump may unknowingly start to initiate a scheduled feature. Never leave a powered pump unattended while the pump is in an unsafe condition unless the pump’s programming cycles are understood (for example, strainer pot lid removed or pipes not connected and system not primed).

    Maintenance for variable-speed pumps is generally the same as that for single-speed pumps.
    Pump strainer baskets (sometimes referred to as the “hair and lint pot”) must be kept clean of leaves and debris at all times. A dirty basket can impact pump and system performance and make the system difficult to prime.

    Protect motors from heat by ensuring that there is shade from the sun and that ample ventilation is available. Particular attention should be paid to the motor’s fan cover and cooling fins to ensure there are no obstructions to air flow. Motors should also be protected from dirt and moisture. Avoid splashing motors with water. Do not store or spill chemicals next to the motor. Avoid installations next to lawn sprinklers and protect them from the weather.

    Some variable-speed pumps come equipped with freeze protection to assist with winterization. This feature will automatically start the pump when temperatures reach a predetermined level to prevent pipe freezing. Whenever systems are drained, power should be removed from the pump to avoid inadvertent starting of the pump.
     

  8. Educate the Homeowner. Once the variable speed pool pump has been successfully installed and tested, the next critical step is to train the homeowner on the capabilities, functions, operation, maintenance, programming, and potential risks associated with the new pump. In order to ensure that energy savings are actualized, the homeowner must understand that the lower flow rates will provide adequate filtration for the pool. However, it is also important to educate the homeowner on the signs of a potentially unclean pool and equip them with information and knowledge to maintain a healthy swimming environment.

Ensuring Success

  • Before system start-up, the pump and system must be manually primed and evacuated of air.
  • Whenever systems are drained, power should be removed to avoid inadvertent starting of the pump.
  • After installation is complete, the installer must program the new pump to obtain adequate filtration, in-pool circulation, water clarity, and sanitation while using the lowest possible motor speed.
  • When installing and programming a variable-speed pump, use caution with old or questionable equipment that can limit pump performance potential and address any suction entrapment hazards.
  • Train the homeowner on the capabilities, functions, operation, maintenance, programming, and potential risks associated with the new pump.

 

Climate

No climate specific information applies.

Training

Right and Wrong Images

None Available

Presentations

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Videos

  1. Ask the Expert: Pool Pumps
    Publication Date: April, 2016
    Author(s): EPA
    Organization(s): EPA

CAD Images

None Available

Compliance

The Compliance tab contains both program and code information. Code language is excerpted and summarized below. For exact code language, refer to the applicable code, which may require purchase from the publisher. While we continually update our database, links may have changed since posting. Please contact our webmaster if you find broken links.

ENERGY STAR Qualified Product list and Energy Savings calculator

ANSI/APSP/ICC-15 American National Standard for Residential Swimming Pool and Spa Energy Efficiency

4.2.1. Pool pump motor controls for use with a two-speed, multi-speed, or variable-speed pumps shall have the capability of operating the pool pump at least at two speeds. The control’s default filtration speed setting shall be no more than one-half of the motor’s maximum rotation rate. Any high-speed override capability shall be for a temporary period not to exceed one 24-hour cycle without resetting to default settings.

5.1.2. For maximum energy efficiency, pool filtration should be operated at the lowest possible flow rate for a time period that provides sufficient water turnover for clarity and sanitation.

5.3.4. Filtration pumps shall be sized, or if programmable, shall be programmed, so that the filtration flow rate is not greater than the rate needed to turn over the pool water volume in 6 hours or 36 gpm, whichever is greater.

5.3.7. Multi-speed pumps must have controls that default to the filtration flow rate when no auxiliary pool loads are operating. The controls must also default to the filtration flow rate setting within 24 hours and must have a temporary override capability for servicing.

5.5.4. All elbows shall be sweep elbows or elbow-type that have a pressure drop of less than the pressure drop of straight pipe with a length of 30 pipe diameters.

This Retrofit tab provides information that helps installers apply this “new home” guide to improvement projects for existing homes. This tab is organized with headings that mirror the new home tabs, such as “Scope,” “Description,” “Success,” etc. If there is no retrofit-specific information for a section, that heading is not included.

Generic ENERGY STAR variable speed pool pump
Generic ENERGY STAR variable speed pool pump (image courtesy of ENERGY STAR).

SCOPE

Replace a residence’s single-speed or two-speed pool pump with an ENERGY STAR certified variable speed pool pump.

  • Calculate the volume of water (gallons) of the swimming pool.
  • Determine the wattage of the existing pool pump.
  • Select an ENERGY STAR certified variable speed pool pump model.
  • Remove and recycle the old pool pump.
  • Install the new ENERGY STAR certified variable speed pool pump.

See the U.S. Department of Energy’s Standard Work Specifications for more guidance on replacing pool pump motors and controls.

DESCRIPTION

Pool pumps circulate and filter swimming pool water to ensure adequate chlorination and maintain clarity and sanitation. The filter removes dirt, leaves, insects, and other debris whereas the chlorination adds sanitizing disinfectants, oxidizers, and algaecides. The pool pump may also provide water flow to the pool sweeper and vacuum and run water features such as a waterfall or fountain. Pumps used in these applications are typically run at full speed for longer durations, increasing energy consumption considerably.

Most pool pumps are centrifugal pumps, driven by a small single-phase motor, typically 0.1 to 5 motor nameplate horsepower for residential and small commercial applications. The pump draws water through the center of the impeller, or rotor, of the pump and generates pressure to overcome flow resistance in the plumbing system of the pool. The pressure head forces the water through the pool plumbing, filtering equipment, and heater (Figure 1). Depending on the design, the pool pump motor may provide single-speed, dual-speed, multiple-speed, or variable-speed operation.

Figure 1. Depiction of a pool plumbing system with filter, heater, skimmer, and pool pump
Figure 1. Depiction of a pool plumbing system with filter, heater, skimmer, and pool pump (source: California Energy Commission)

Pool pump and motor combinations are typically sold when a homeowner installs a pool or upgrades an existing pool pump and motor combination from a single-speed to a dual-speed or variable-speed system. As a low-cost alternative, electric motor manufacturers sell replacement pool pump motors since the motor can fail before the pump. Pool pump and motor lifetimes are dependent upon the design. The typical life expectancy is five to seven years.

A pool owner can achieve significant energy savings by running the pool pump at the lowest available motor speed that meets the minimum water flow requirements of the task. Different pool pump technologies allow the pool owner to select the speed adequate to the pool maintenance task. Variable-speed pool pumps provide the most flexibility and provide the greatest savings.

Variable-speed pump motors are powered by electronically-commutated motors that allow a user to select a speed that suits the pool maintenance task. The controls or electronics of the motor modify the incoming AC current and commutate the current to a three-phase wave form to set the motor speed and minimize electrical losses. A variable-speed motor may provide speeds as low as 1/8 of full speed. The slower speeds achieved by variable-speed motors offer quieter operation and longer service life than available at half speed with a dual-speed motor.

A variable-speed pool pump motor achieves more energy savings than dual- and multiple-speed motors in two ways. First, the pool owner may select a slower speed to accomplish circulation and filtration than available on a dual- or multiple-speed motor. Second, variable-speed motors use a permanent magnet rotor design, which achieves greater efficiency than an AC induction motor while running at the same speed since no current is necessary to power the rotor magnet required by the AC induction motor.

ENERGY STAR certified variable speed pool pumps can save significant energy and money over conventional or two-speed pumps
ENERGY STAR certified variable speed pool pumps can save significant energy and money over conventional or two-speed pumps (source: U.S. EPA).

Pool owners should select ENERGY STAR certified variable-speed pool pumps when replacing old or broken pool pumps. The most obvious sign that a pool owner needs a pool pump is when the motor is completely dead. However, there are other warning signs, such as when your existing pool pump:

  • Is seven to ten years old.
  • Does not seem to be as powerful.
  • Continually makes noise.
  • Gets hot and shuts down.
  • Hums or buzzes but will not start.
  • Starts slowly.

ENERGY STAR certified variable-speed pool pumps save up to 70% on energy bills over conventional pool pumps (Figure 2). This amounts to a savings of $350 and 2,800 kWh per year over conventional pool pumps. The payback on the incremental cost is 1.6 years and the lifetime savings amount of $2,900.

There are more than five million in-ground pools installed in the U.S. and over 150,000 new pools are built annually. If all pool pumps sold in the United States were ENERGY STAR certified, the energy cost savings would grow to $155 million each year and 2.5 billion pounds of annual greenhouse gas emissions would be prevented, equivalent to the emissions from more than 260,000 vehicles.

HOW TO REPLACE A POOL PUMP

1. Inspect the Pool Area

  • Carefully inspect the entire pool area for exposed wiring, trip hazards, pests, or animals.
  • Inspect the pool pump containment room and any exposed plumbing to ensure that any leaks or damage to existing pool plumbing are identified and repaired.
  • Locate the main electrical circuit breaker panel and identify and confirm which breaker is designated for the pool pump.

2. Measure the Pool and Calculate Pool Volume

  • Calculate the volume of water (gallons) in the pool to size the pool pump for the correct flow rate. The pool’s entire volume of water needs to “turn over” (i.e., complete a full cycle of pool water volume circulation) to maintain clarity and sanitary conditions within a 24-hour period. This limits the potential for pathogens and algae to build up.
  • To determine the maximum and minimum pool filtration rates, the installer must first calculate the entire volume of pool water. First, calculate the cubic feet of pool water, then convert this to gallons. For simple, flat-bottomed, rectangular swimming pools, calculating cubic feet of water is straight forward by measuring and multiplying the length, width and depth of the pool:

    Pool length x width x depth = cubic feet of pool water (volume)
    Then, convert the cubic feet of water to gallons using this formula:

    Cubic feet of water x 7.48 = Total pool volume in gallons

  • Since pools come in countless designs, shapes and depths, calculating pool volume is rarely so straight forward. To calculate the cubic feet of water for oblong, circular, sloped, nonlinear sloped, and custom pool designs, more advanced mathematical calculations are required. There are several free pool volume calculation tools available online to perform these calculations, including the calculator available at SwimmingPool.com.
  • After calculating the volume of the pool in gallons, you can calculate the minimum flow rate of the pool pump by dividing the total pool volume (gallons) by 1,440 (total minutes in a day). The minimum filtration flow rate is the least amount of water (gpm) the pool pump must circulate through the filtration system in order to achieve the minimum daily turnover:

    Total volume of pool / 1,440 = Minimum filtration flow rate (gpm)

  • Next, you can determine the maximum pool filtration rate. The pool pump should not have a filtration rate greater than the rate needed to turn over the pool water volume in six hours, or 36 gallons per minute (gpm), whichever is greater. This equation was developed by the California Energy Commission and was adopted by the Association of Pool and Spa Professionals to help set guidelines for achieving the maximum energy efficiency in pool pump operation. To calculate the maximum filtration flow rate, divide the total volume of water in the pool by 360:

    Total volume of pool / 360 = Maximum filtration flow rate (gpm)

  • For pools with less than 13,000 gallons of volume, the pump must have a gpm rating of 36 gpm, or less.

3. Calculate the Total Dynamic Head (feet) for the Pool

  • Total Dynamic Head (TDH) refers to the total equivalent height that the pool water is pumped after taking into consideration any friction losses in the pipes. A pump’s flow rate is dependent on the feet of head in the plumbing system, which is a measurement that’s featured in the curve chart in a pool pump’s owner’s manual.
  • Measure the lengths of all the pipes and account for all turns, valves, and tees.
    • Measure the pipe lengths traveling from the main drains, skimmers and any other suction ports that draw water from the pool. While measuring lengths, also take note of the depth of the pipe, number of turns, and type of turns (e.g., 45-degree or 90-degree.) The type of turns will affect the friction loss calculation. Measure the lengths of the pressure side pipes in the same manner, noting the degree of turns and any valves.
    • Convert the turns, valves, and tees to equivalent length of pipe using a conversion factor table. Add the equivalent feet of pipe from the turns, valves, and tees to the pipe length you’ve measured to determine a total equivalent pipe length for all of the pool plumbing.  
    • The amount of friction loss in PVC pipe depends on how fast the water is flowing through the pipe. Approximate the flow rate (gpm) through the pipes. Generally, this number should be close to the pool filter Design Rate of Flow, check the filter specifications.
    • Pool plumbing is usually either 1.5” PVC or 2” PVC, Schedule 40 pipe. Use a PVC pipe friction loss conversion table to determine the total feet of head for the pool pipes, turns, valves, and tees.
  • Account for the filter, heater, and any other equipment.
    • Filters slow down water as it rushes through the plumbing, and this resistance should be factored into the calculation. Filter manufacturers provide head loss charts that list the ratings of their products. Owner’s manuals are also a resource for head loss. If a new filter is needed, select a model that is oversized to be absolutely certain it can handle the flow coming from the pump. For instance, instead of getting a filter rated at exactly 42 gpm, select one that is a little higher, such as 60 gpm.
    • The head loss for heaters varies depending on flow rate and model. Check the owner’s manual or contact the manufacturer for the feet of head for the heater. The same should be done for any chlorinators, purifiers, or other equipment.
  • Calculate the total feet of head for the pool plumbing system. You should now have the information required to select the size of your pool pump: total dynamic head (feet), minimum flow rate (gpm), and maximum flow rate (gpm). Most pool pump manufacturers provide charts indicating the HP required for a particular gpm and Foot of Head.

4. Selection of the ENERGY STAR Certified Variable Speed Pool Pump

  • The pool owner will want to choose an ENERGY STAR certified variable speed pump model that meets the total dynamic head, minimum flow rate, and maximum flow rate requirements. Manufacturers typically provide the total dynamic head, minimum flow rate, and maximum flow rate charts for their models online to determine the appropriate HP to meet the needs of the pool. If this information is unavailable, contact the manufacturer or a pool pump dealer to request the information.
  • Once the replacement pool pump is selected, the pool owner should use the ENERGY STAR Product Finder to ensure the variable speed pool pump model is certified by ENERGY STAR and has the proper specifications.
  • The homeowner will want to check the Database of State Incentives for Renewables & Efficiency® or the ENERGY STAR Rebate Finder to determine whether the variable speed pool pump model is eligible for a rebate or incentive in the area.

5. Evaluate the Power Draw and Energy Use of the Existing Pump

  • Power for pool pump motors designed for the U.S. market is calculated using the formula:
    Amps x Volts x Power Factor = Watts
  • Although every motor has a power factor rating, it can be difficult to access accurate information for every pump on the market, as the service factors and load factors all vary. The best way to determine kilowatt (kW) usage is to use an RMS kilowatt meter, which measures how many kWs the pump draws. Using a kW meter is just like using an Amp meter but you must measure both volts and amps.
    • First, put the meter dial on kW and turn the pump on.
    • Next, place the black and red leads on the terminals supplying voltage to the pump (this can be done at the time clock or relay, depending on the installation).
    • Then, clamp the meter around one of the hot wires and read the pump’s kW usage.
    • As with any electrical wiring evaluation, extreme care should be taken when using the RMS kilowatt meter, especially around areas that have standing water.
  • Once the wattage use of the pump has been determined, calculate the daily and annual energy consumption of the motor (kilowatt-hours, kWh), and the estimated cost of pool pump operation.
    • Convert the kW power measurement to daily energy use (kWh) by multiplying the kW by the average number of hours the pump is operated per day. Determining the hours of operation per day can be done by reviewing the timer and/or interviewing the homeowner.
    • Keep it in mind that pool pump motors have a service factor (SF) rating or overload capacity designed into the motor. There is a practice in the swimming pool pump industry of using high service factors where the total horsepower (and subsequent kW demand) is much greater than the nameplate would imply. For general-purpose motors, service factors are rarely greater than 1.15. However, swimming pool motors are designed exclusively for use in the pool industry, and many have exceptionally large service factors as high as 1.65 or 1.9. As a result, a 1½-hp pump with a service factor (SF) of 1.47 can easily draw around 2,100 watts or 2.1 kW.
    • Next, convert daily energy consumption to annual energy consumption by multiplying the daily energy use (kWh) by the number of the days that the pool is in use per year.
  • Finally, multiply the annual energy consumption by the pool owner’s typical electricity rate ($/kWh) on the household’s electricity bill to determine annual operating cost.
  • Using the owner’s manual for the new ENERGY STAR certified variable speed pool pump, calculate the annual energy consumption and operating cost. Taking the difference in operating cost between the old and new pool pumps will provide an estimate of the annual cost savings of the new pool pump.

6. Disconnect and Remove the Old Pool Pump

  • Plan ahead when helping pool owners remove and recycle their old pool pumps. Pool pumps can contain metals and parts that should be recycled. Many municipalities offer drop-off recycling service for pool pumps. Pool pumps can also be given to repair shops for spare parts. It’s good practice to identify the destination of the pool pump before removing it.
  • Removal and replacement of the pool pump requires the tools needed for rewiring any basic electric circuit and cutting and gluing PVC pipe, including:
    • Electrical meter: preferably True RMS clamp-on kW and multi-function style meter.
    • Miscellaneous: Screwdrivers, slip-joint pliers, channel-lock pliers, wire cutters, wire strippers, wrenches, sand paper.
    • Pipe cutter: ratcheting PVC cutter, reciprocating saw, chop saw or hacksaw
  • Verify the electrical supply voltage and wire and circuit breaker size and ensure that these are compatible with the replacement variable speed pump and in accordance with national, state, and local codes and permits.
  • When selecting common PVC fittings, use of schedule 40 or 80 pipe is recommended. It is not advisable to use lower pressure rated drain, waste, vent (DWV)-style pipe and fittings for pool circulation systems. Though rare, occasionally copper pipe may be found in older pools.
  • To expedite the installation process, build an ample inventory of common materials such as 90° elbows, 45° elbows, couplings, unions, valves, pipe, PVC glue and primer, threaded nipples to attach to the pump, pipe thread compound or Teflon tape.
  • Inspect and note the threaded fitting size of the replacement pump housing. Most are 2” male pipe thread (MPT), and some pumps come equipped with the threaded fittings and unions.
  • Measure the overall pump dimensions and compare the existing pump to the replacement variable speed unit. Pay special attention to the suction port height, and distance from pump suction port to discharge port as these critical dimensions vary amongst pumps.
  • Have a plan for how the replacement pump will fit and where it is best to make cuts before the old pump is removed from service. Also note locations of junction boxes to ensure sufficient wire and conduit is available.
  • Shut off power to the pool pump at the breaker panel and place a piece of tape over the breaker switch to ensure no one turns it back on while you’re working. Use an electrical meter to ensure the wires are dead.
  • Disconnect electrical wires at the pump junction box.
  • Mark the location and use a pipe cutter, hacksaw, or reciprocating saw to cut the discharge and suction pipe.
  • Remove the existing pool pump.

A reciprocating saw works well to cut PVC pipe during pool pump installation
A reciprocating saw works well to cut PVC pipe during pool pump installation

7. Install New ENERGY STAR Certified Variable Speed Pool Pump.

  • Ensure that the work area is clean and free of obstructions.
  • Place the replacement pump in position and align the suction and discharge pipes. Shims may be required to compensate for varying pump heights and should be used to create a level and stable connection height.
  • Install threaded fittings in pump suctions and discharge ports using thread sealant.
  • Avoid installation of 90° elbows directly into the pump inlet as these greatly increase friction or total dynamic head (TDH). If the installation allows, install a length of straight pipe at the pump’s suction port that is equal to five times its diameter. For example, with a 2” diameter pipe, install a straight pipe 10” long prior to entering the pump’s inlet. This will aid in the pump’s priming and general performance.
  • After all fitting and connections have been made, reconnect the electrical conduit and wires per national, state, and local codes. Also, ensure the ground bonding wire is connected to the pump’s bonding lug.
  • Most existing single-speed pumps are electrically powered through a timer or automation system to schedule their daily operation. Newer variable speed pumps have the time clock and scheduling feature inherent in their control system. For these pumps, it is preferable to wire them directly, bypassing the existing time clock. For installations with remotely operated automaton systems, the pump may be powered through relays. This is done to ensure that the pump has a continuous uninterrupted power supply.
  • After installation is complete, program the new pump to obtain adequate filtration, in-pool circulation, and water clarity while using the lowest possible motor speed.
  • Variable speed pumps need to run longer to accomplish the required turnover due to their lower flow rates. As a result, the pool spends much more time skimming the water and preventing debris from sinking. The result is a cleaner pool with improved water clarity, another benefit derived from running pumps at a slower rate and for longer periods of time.
  • The variable speed pump should be set up to operate at a speed that will turn over the pool volume at least once during every 24-hour period. For pools with high debris and/or bather loads, additional turnovers may be required to maintain adequate water quality. In no event should the turnover time be less than six-hours during normal operation.
  • Reducing the flow through main drains by throttling the drain’s return line valve (if applicable) can improve skimmer performance by providing the pump with most, or all of the water from the skimmer. However, this configuration must be tested to confirm the pump is supplied with enough water when operating the pump at the highest speed needed by the pool. This is often not the highest speed at which a pump can operate and should only be high enough to achieve the intended purpose, such as operating cleaner therapy jets, or a water feature.
  • The start-up flow rate may need to be higher for several minutes to fully prime the pump, purge air from the filter, and fill solar panels with water. Once these start-up tasks have been completed, the pump speed can be reduced to the energy efficient low-speed setting.
  • Pools sometimes need higher turnover flow rates. For example, following a storm or pool party, higher turnover flow rates may be required. It is advantageous to have this feature set up in advance to provide the pool owner with a mode that will temporarily override the normal filtration flow rate without the need for reprogramming the pump controller.

8. Test the Filtration Flow Rate

  • Always follow the pump manufacturer’s instructions and guidelines, especially the warning and safety instructions. The instructions listed are not comprehensive and do not substitute for adherence with the manufacturer’s instructions.
  • During the removal and installation process, air can enter the system and become pressurized. Before system start-up, the pump and system must be manually primed and evacuated of air. Care should be taken to vent system air through the filter’s manual relief valve.
  • Caution: do not run the pump dry. To prime, remove the strainer pot lid and fill the pump with water until the level reaches the suction port, and then replace the strainer pot lid. This prevents the pump from running dry, which will damage the mechanical seal. Start by opening the manual relief valve on top of the filter and then press the button to start the pump. Next, you must bleed air from the filter until a steady stream of water comes out, and then close the manual air relief valve.
  • Remember, the basic premise of variable speed energy-saving pump operation is “run it slower and run it longer.” By running the pump slower, a slight reduction in water flow (gpm) will greatly reduce the electrical demand (kW). By reducing the flow rate, runtime will have to increase to ensure that the water is adequately filtered and mixed.
  • After the pump has been started and is successfully circulating water through the filtration system, filtration flow rates need to be verified. Water is supplied to the pump from both the skimmers and main drains; however, the skimmers should supply the majority of the flow. Minimum filtration flow rates need to ensure that the skimmers function adequately. Most skimmers take approximately 25 gallons per minute (GPM) of flow for adequate performance. Verification of performance can usually be accomplished by visually observing surface water drawn into the skimmer face and over the weir door.
  • Skimmer baskets need to be checked and cleaned regularly. Main drain flow should complement the skimmer flow but should be minimized to prevent suction entrapment hazards. The main drain and suction covers should be visually observed. A broken or missing drain cover poses a serious health risk and should be replaced immediately, even before the pool is returned to service.

9. Calibrate the flow of new pool pump to obtain adequate circulation at lowest possible motor speed.

10. See the new home Description tab for more information on programmable pumps, maintenance, and home owner education.

ENSURING SUCCESS

A pool pump installer should:

  • Inspect the pool area and identifying possible hazards, then ensuring the area is ready for maintenance and pool pump replacement.
  • Calculate the volume of the swimming pool to determine the total amount of flow required to adequately circulate water through the filtration system.
  • Determine the wattage use of the existing pool pump and amount of usage on a daily basis to estimate total annual energy use of the pump.
  • Estimate expected usage of new pump to calculate expected energy use and savings.
  • Calibrate the flow of the new pool pump to obtain adequate circulation at the lowest possible motor speed. The minimum speed required is one that would lead to a 12-hour turnover (per ANSI/NSPI-5 2003). Turnover is the period of time required to circulate a volume of water equal to the pool’s volume.

COMPLIANCE 

See Compliance tab. 

More Info.

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Case Studies

None Available

References and Resources*

  1. Author(s): The Association of Pool & Spa Professionals
    Organization(s): The Association of Pool & Spa Professionals
    Publication Date: July, 2015
    View the APSP/ANSI Standards and codes below to get information about ANSI specifications for pools, spa and hot tubs.
  2. Author(s): U.S. Environmental Protection Agency
    Organization(s): EPA
    Publication Date: July, 2018

    Table of criteria for pool pumps to achieve ENERGY STAR certification.

  3. Author(s): Department of Energy
    Organization(s): DOE
    Publication Date: July, 2018

    You can save energy and maintain a comfortable swimming pool temperature by using a smaller, higher efficiency pump and by operating it less.

  4. Author(s): U.S. Environmental Protection Agency
    Organization(s): EPA
    Publication Date: April, 2017

    Factsheet with information on energy efficient pool pumps.

  5. Author(s): Hunt, Easley
    Organization(s): BARA, National Renewable Energy Laboratory, Building Media
    Publication Date: May, 2012

    Research study showing that for a relatively small investment, a variable speed pool pump can reduce pool pump energy use by 50% to 75%.

  6. Author(s): Owrth, Ludovici, Joyce, Fernstrom
    Organization(s): California Investor-owned Utilities
    Publication Date: July, 2013

    This CASE report proposes updates and revisions to the standards for residential swimming pool filtration pumps, new and replacement single phase pump motors under 5 horsepower (HP), controllers, portable electric spas as well as expanding the scope of the current standards to include light emitting diode (LED) pool lighting.

  7. Author(s): California Energy Commission
    Organization(s): California Energy Commission
    Publication Date: June, 2016

    This report discusses proposed updates to the pool pumps and motors, and portable electric spas standards in the Appliance Efficiency Regulations (California Code of Regulations, Title 20, Sections 1601 to 1609). These proposed updates are part of the 2012 Appliance Efficiency Rulemaking, Phase I (Docket #15-AAER-02).

  8. Author(s): U.S. Environmental Protection Agency
    Organization(s): EPA
    Publication Date: October, 2016

    ENERGY STAR pool volume calculator in a spreadsheet format.

Contributors to this Guide

The following authors and organizations contributed to the content in this Guide.

Florida Solar Energy Center, lead for the Building America Partnership for Improved Residential Construction (BA-PIRC), a DOE Building America Research Team

Home Innovations Research Labs, lead for the Partnership for Home Innovation (PHI), a DOE Building America Research Team

Steve Easley & Associates

Pacific Northwest National Laboratory

Last Updated: 07/16/2018