What VS Pump Should you Buy?
If you got here just looking for guidance on what VS pump you should buy it is nearly always advantageous to go with a larger Total Horse Power (THP) VS pump in a pump family for both lower noise and greater efficiency.
Because of the way WEF is defined, larger pumps always have lower WEF and look like they are less efficient even though they are more efficient at the same flow rate.
Let's look at a case study with the Hayward TriStar VS pump:
The TriStar VS 1.85 HP has a Weighted Energy Factor (WEF) for 115V = 12.9 and 230V = 8.3. The higher the WEF, the more efficient the pump.
The TriStar VS 2.7 HP has a Weighted Energy Factor (WEF) for 115V = 10.1 and 230V = 7.3.
But look at the performance data on Haywards website:
At 40% the 2.7 pump is running 51 GPM into 10 ft head while the 1.85 HP runs 29 GPM. So you get better WEF with the 1.85 with a lower flow. If you crank down the 2.7 pump RPM to the 29 GPM the energy used is likely to be better with the larger pump.
A Larger HP VS Pump is Quieter than a Lower HP VS Pump
A larger HP pump or a smaller HP pump will use about the same amount of energy for a given flow rate on a particular system. Your pool needs the pump to deliver a range of water flow rates through the pipes, filter, heater, and other equipment. As long as the pump can deliver the needed water flow range through the restrictions, called head, a large HP or small HP VS pump can work equally well.
All pool pump motors run at a maximum of 3450 RPM. The impeller determines the required motor HP and the flow capacity of a specific pump at a specific speed on a specific system
The main benefit to selecting a larger HP pump is it will run at a lower RPM to give you the flow rate you need and thus be quieter.
Pump U.S. DOE Regulations
The US Department of Energy (DOE) implemented Federal Energy Efficiency regulations, as of July 19, 2021, on Dedicated Purpose Pool pumps (DPPP). Don't you love government acronyms? If you do, there are more to come courtesy of the DOE.
Pool pumps manufactured for use in and imported for use into the U.S. after July 19, 2021, must meet new minimum efficiency standards. Any pumps that are in the US before July 19, 2021 can continue to be sold. So for some period of time the old non-compliant pumps will be available and you can buy them until they run out of stock. At the same time manufacturers will be selling and promoting their new energy efficient pumps.
There is no requirement for a consumer to replace any old pump until it fails and needs replacement. At this time there are no regulations restricting repairs on old non-compliant pumps although regulations on pool pump repairs are being proposed in Congress.
A single speed pool pump can be the second highest electrical energy consumer in a house after the HVAC system. The energy savings from using a VS pump can payback the VS pump cost in a short period of time.
The regulations do not differentiate between residential or commercial use of pool pumps and apply to all uses.
To understand the way pool pumps will be sold we need to explain the new pump categories and terminology for horsepower and energy efficiency. Then we will explain what it means to you the pool owner and consumer.
Different Type of Pool Pumps Have Different Energy Standards
The DOE regulations create the following pump classifications with minimum efficiency standards:
- Self-priming - these pumps used to be called inground pumps
- Large inground filter pumps (self-priming) - These are typically 1 horsepower (HP) or greater.
- Small inground filter pumps (self-priming) - These are typically 1/2 HP and 3/4 HP pump.
- Non-Self-priming - these pumps used to be called aboveground pumps
- Pressure cleaner booster pumps
The following pumps do not have minimum performance requirements:
- Waterfall pumps that run at 1,800 RPM max
- Filter pumps with integrated sand and cartridge filters (e.g., small inflatable pools)
- Rigid (permanent) and storeable (inflatable) electric spa pumps (e.g., pumps for hot tubs)
The following pumps are exempt from the DPPP efficiency requirements:
- Three-phase pumps
- electric spa (hot tub) pumps
- pumps greater than 2.5 HHP (approximately 5 total horsepower [THP])
How Has The DOE Regulations Changed Pump Terminology?
In addition to defining pumps as self-priming and non-self priming the regulations change the definition of Horsepower. With the old pumps the power of the pump was stated as it's horsepower (HP) which would be on the pump motor. Motors would also have a Service Factor (SF) and the Total Horsepower would be the HP x SF. This would all be listed on the motor data plate. All of these horsepowers on the old pumps stated what the motor could do but did not tell how effeciently or effectively the pump could move water.
Three new labels will be on new pumps and replace the old HP and SF ratings:
- WEF (Weighted Energy Factor)—This is a measure of the pump’s energy efficiency (how much much water is pumped divided by how much energy it takes), similar to miles per gallon in an automobile. The higher the WEF, the more efficient the pump. Each pump must be labeled with its WEF.
- HHP (Hydraulic Horsepower)—This is the amount of hydraulic power produced by the pump’s wet-end
- THP (Total Horsepower) or SFHP (Service Factor Horsepower)—This is the new pump HP rating and is determined by the total HP created at the motor shaft. Each pump must be labeled with its THP.
HP ratings will be redefined so that all pumps have a Service Factor of 1.0, and the HP displayed on the pump will be the THP (also referred to as Service Factor Horsepower [SFHP]). The new version of the same pump may have a different HP number using the THP ratings although the motors are identical.
It is HHP, not HP or THP, that defines the performance of a pump. When comparing the performance of new pumps HHP and WEF are the important factors.
Each pump must be labeled with its WEF and THP. HHP is not required on the pump label and Pentair said it is adding it to all pump labels. We will have to see what other pump manufacturers do with their labeling.
Seeing the pump HP alone does not tell you the entire story on pump performance. For example, a 1 HP motor pump can have very different HHP performance depending on the impeller the manufacture installs. The HHP can vary from 0.5 to 1.0 HHP depending on the impeller. This will become important to what pump manufactures do with their products as pumps with a HHP of .711 and above have a higher WEF requirement then pumps below .711 HHP.
How Do the New Regulations Affect Buying a New Pool Pump?
In 2021 there will be a transition period when both pool pumps not affected by the new regulations will be sold as well as pool pumps labeled under the new DPPP regulations. The old motor HP ratings of pumps will not be directly comparable to the new THP and HHP pump labeling. So comparison shopping during the transition can get confusing.
Eventually only Dedicated Purpose Pool pumps (DPPP) that meet DOE energy standards will be available. Single speed and 2-speed pool pumps that were 1 HP and greater under the old standards will not meet the energy efficiency standards and will not be available. To get a pool pump over 1 HP a Variable Speed (VS) pump will be necessary.
Some manufactures will still have smaller single speed or 2-speed pool pumps that have a HHP below .711 and meet the energy standards. These small single speed pumps may have higher HP motors on them but have smaller hydraulic impellers that set the pump at a HHP of .711 or less.
In shopping for a new in-ground pump the HHP is the best measure of pump power, not the motor HP or THP. Then you can compare WEF between pumps if energy efficiency is important to you. VS pumps are likely your choice.
The best way to choose a VS pump is to pick the largest THP pump in the product line of your favorite manufacture or compatible with your controller. Then when operating the pump, choose the lowest RPM for the given task and you will be operating efficiently.
Most above-ground non-self priming pumps will be compliant and change little, although their associated horsepower ratings may change. Single speed pumps will continue to be common when low HHP will work on a simple pool. AGPs with heaters and solar will need to consider VS pumps to meet their HHP needs.
When shopping for a combination pump and filter bundled together in a single unit, that is used with storable pools, you will find they now include a timer that automatically turns the pump off after 10 hours.
Pressure cleaner booster pumps will continue to be single speed low HP.
What Are The Major Pool Equipment Manufactures Saying?
The major pool equipment manufactures response to the DOE regulations will develop as we see the complaint pumps come to market. As of July 2021 what we know is...
Pentair looks committed to having three product lines of pool pumps that are all Variable Speed:
- IntelliFlo VSF
- SuperFlo VST
- IntelliPro VSF
Pentair also has a line of single speed Spa and Water Feature pumps and Waterfall pumps.
Pentair explains the DOE regulations and exemptions in this FAQ.
Pentair has a Pool Pump Savings Calculator.
Hayward is maintaining both their large VS pump product line with the Tristar VS Series; new TtiStar XE Extreme Efficiency pumps; and single speed product lines with the Super Pump Single Speed, Maxflo XL Single Speed, and new 1.1 HP SS TriStar. Hayward claims, as of July 2021, their TriStar VS Series has the highest WEF in the industry at 12.9 and their TriStar XE Series has a WEF of 9.3..
Hayward says all Hayward Super Pumps and MaxFlo XL single-speed pumps 1 HP and lower meet the new DOE energy-efficiency standards. We will need to see what HHP these pumps deliver to judge their performance.
Hayward has a Pool Pump Energy Calculator.
Jandy says all Jandy variable speed pumps are compliant:
- VS FloPro 0.85 HP 115V
- VS FloPro 1.65 HP 230V
- VS FloPro 1.85 HP 115V/230V with 2 Aux Relays
- VS FloPro 2.7 HP 115V/230V with 2 Aux Relays
- VS PlusHP 2.7 HP 115V/230V with 2 Aux Relays
- VS ePump 2.2 HP 230V with 1 Aux Relay
- VS ePump 2.7 HP 230V with 1 Aux Relay
Jandy will also have some single speed, 2-speed pumps, and 3-phase pumps:
For more details see Jandy DOE Compliant Pool Pumps. This document also lists non-compliant pumps with transition options.
Jandy has a interactive energy savings calculator.
Pump Technical Details
What is WEF?
WEF is NOT indicative of pump efficiency despite what the industry will say. It penalizes larger HP VS pumps even though they may rarely be operated at higher speeds. WEF tends to lead the pool owner towards smaller HP VS pumps which are usually less efficiency and are louder in operation.
Weighted Energy Factor (WEF) standardizes pump efficiency the same way MPG standardized motor vehicles. WEF measures the gallons of water pumped per kWh of energy use. The higher the WEF score, the more gallons of water pumped per kWh. So a pump with a WEF score of 7.356 means the pump can move 7,356 gallons of water while using 1 kWh of energy.
WEF = Gallons Pumped / 1,000 Watts Used
The WEF weighted score is:
- 80% at low speed
- 20% at high speed
WEF is required to be published on the pump rating label for pumps manufactured after July 19, 2021
Use WEF to compare energy efficiency of pumps. WEF is only one factor to consider in pump selection. Pumps need to be sized properly for its application which brings us to HHP.
Further Note on WEF pump ratings.
What is HHP?
Hydraulic Horsepower (HHP) standardizes how pumps are compared in terms of water horsepower. This is not the same as motor horsepower. A higher HHP means more water is being pumped and higher head pressures are being generated.
HHP is directly proportional to pump flow. HHP should be used to size pumps rather then motor horsepower which has historically been used.
HHP is approximately 50% of the pump motor’s total horsepower (THP) rating.
What are Self-Priming Pumps?
Self-priming pumps are typically used in in-ground pools. A self-priming pump is capable of 5 feet or more of lift in 10 minutes. Self-priming pumps are needed when the pump is placed at or above the pool waterline.
What are Non Self-Priming Pumps?
Non self-priming pumps are typically used in Above Ground Pools (AGP) and are not capable of 5 feet of lift in 10 minutes. They are placed below the water line and do not need to lift water to prime the pump.
What are Waterfall Pumps?
Waterfall pumps have a maximum head of less than or equal to 30 feet and a maximum speed less than or equal to 1,800 RPM.
For the DOE regulations a Waterfall pump is based on the pump specifciations and not the installation or application.
What are Integral Sand and Cartridge Filter Pool Pumps?
Integral sand and cartridge filter pool pumps are bundled with a filter in a single unit where the pump cannot be plumbed to bypass the filter. The combination pump and filter units are typically used in small aboveground pools and storable pools.
The DOE regulations require combination pump and filter units under this classification to include a timer that automatically turns the pump off after 10 hours.
The Replacement Motor Loophole
The 2021 DOE regulations do not place any restrictions on replacement motors for either old non-compliant pool pumps or for newer DPPP compliant pumps. A pool pump motor could fail before the variable speed DPPP needs to be replaced. A concern is whether an unknowing homeowner or contractor might replace it with a single-speed replacement motor, which would negate the benefits of the variable speed pump.
The DOE is considering a supplementary motor rule that would likely restrict the sale of non-variable-speed motors with THP greater than 1.15. The rules would set a prescriptive standard that all pool pump motors on the market must meet, regardless of whether they are being sold with a new pool pump or as a replacement. The anticipated DOE “Motor Rule” is likely to be effective in 2022, however the effective date is uncertain.
California has its own rules, currently in effect, about replacement pool pump motors. CEC Title 20 Section 1605.3(g)(5) requires any motor used for residential filter pump applications and manufactured before July 19, 2021 that is greater than or equal to 1.0 THP be replaced with a two-speed or variable speed motor. Effective July 19, 2021 CEC Title 20 1605.3(g)(6) requires any motor used for replacement dedicated-purpose pool pump motor on all residential and commercial applications and manufactured on or after July 19, 2021 that is greater than or equal to 0.5 THP be replaced with a variable speed motor.
- Energy Star Program Requirements for Pool Pumps
- DOE Docket: 2017-01-18 Energy Conservation Program: Energy Conservation Standards for Dedicated-Purpose Pool Pumps; Direct final rule
- eCFR: PART 431—ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT
- Hydraulic Institute Pumps.org
- Pool and Spa News:What to Know About the Department of Energy Pool Pump Rule
- Regal - New Department of Energy (DOE) Pool Pump & Motor Regulations