If your single-speed pump just died, this article is mostly settled for you. You're buying variable speed either way, and the only question is which one. The variable-speed pump picks cover that.
This is for the other case. The pump runs fine, the bill is ugly, and someone has told you to convert. Sometimes they're right. Sometimes the numbers don't get there before the new pump wears out.
Key takeaways
- DOE's national average put a single-speed pump's first-year running cost at $774 and a variable-speed pump's at $223, in 2015 dollars. That's 71% less.
- Pool pump motors from 1.15 to 5 total horsepower made since September 29, 2025 have to be variable speed. The single-speed replacement motor is gone in the sizes most pools use.
- Your heater, salt cell and cleaner decide how slow you can run. Most of them need somewhere between 20 and 40 GPM.
- A variable-speed motor on a sound pump costs about a third of a whole new pump, but none of the rebates I found will pay for one.
- Rebates I checked in September 2026 ran from $300 to $900, and every one required an ENERGY STAR certified pump.
What you can actually buy now
Two federal rules changed the shelf. Both are written in terms most owners never see, and one of them gets misquoted all the time.
The 2021 pump rule. Since July 19, 2021, a new inground pool filter pump above 0.711 hydraulic horsepower has had to meet an efficiency score. DOE set that score at the level of a variable-speed pump. Hydraulic horsepower is the work the pump does on the water during DOE's test. It is not the number on the label. DOE put the line there so that most pumps rated 1 total horsepower and below would fall under it.
That's why the small single-speed pumps survived. Hayward still lists the 1.10 THP Super Pump, and Pentair's WhisperFlo is down to one single-speed model at 1.1 THP. The bigger single-speed pumps are gone from both ranges.
The 2025 motor rule. Since September 29, 2025, every pool pump motor made from 1.15 to 5 total horsepower has had to be variable speed. That covers a motor inside a new pump and a motor sold on its own. So the like-for-like single-speed replacement motor stopped being made in the sizes most pools use.
2027 closes the gap. Motors from 0.5 to 1.15 total horsepower follow on September 28, 2027. Those 1.1 THP survivors sit inside that range.
Both rules cover what gets manufactured after those dates. Older stock can still turn up, and nothing in either rule makes you pull out a pump that works. California got there first. DOE's 2023 rule notes that the state already required variable speed on replacement motors from 0.5 THP up.
Everything here is about inground pumps. Above-ground pumps are rated in a different class.
What it saves, from the people who wrote the rule
DOE had to show its math before it could set the 2021 standard. Its national average put a single-speed inground pump's first-year running cost at $774 and a variable-speed pump's at $223, in 2015 dollars. That's 71% less. It's the figure I trust most, because a federal agency had to defend it in public.
ENERGY STAR explains where the money goes. Filtration "only requires half the flow rate of running a pool cleaner." A single-speed pump can't slow down, so it runs at cleaning speed all day. Slow the pump down and the power falls much faster than the flow. ENERGY STAR's version is that half the speed takes an eighth of the energy.
Real pumps don't quite hit the textbook, and it's worth knowing by how much. I went through ENERGY STAR's test data for the 127 inground variable-speed listings that report every test point:
| Typical draw | Energy per 1,000 gallons | |
|---|---|---|
| Low speed, about 1,300 RPM and 31 GPM | 117 W | 62 Wh |
| Full speed, about 80 GPM | 1,530 W | 315 Wh |
Moving water slowly took about a fifth of the energy per gallon. The textbook predicts about a seventh at those flows. The motor and its drive lose some efficiency at low speed, so part of the promised saving never shows up. At 80% speed, real pumps match the textbook almost exactly. The gap only opens at the bottom.
So the physics holds. It's just a little less generous than the arithmetic you'll see in sales material.
Work out your own number
Start with what the old pump actually draws. Work it through from the inputs in DOE's model of a typical inground pump, and a single-speed motor on it draws somewhere between about 1,550 and 2,170 watts, depending on how efficient the motor is. That's a wide spread, so measure yours if you can.
If your utility shows hourly use, compare an hour with the pump running against one without. Or clamp an amp meter on one supply wire. Volts times amps gives a figure a little above the real wattage, because a motor's power factor is under 1. Treat it as an upper bound.
I'll use 1,900 watts for eight hours a day, which is where the pump running cost calculator starts:
1,900 W × 8 hours = 15,200 Wh, or 15.2 kWh a day.
Now the season and the price. DOE assumed a 12-month season in Florida and California, and four months in New Jersey. The rates are EIA's residential averages for the first half of 2026:
- Florida: 15.2 kWh × 365 days × $0.1536 = $852 a year
- New Jersey: 15.2 kWh × 123 days × $0.2365 = $442 a season
- California: 15.2 kWh × 365 days × $0.3317 = $1,840 a year
Apply DOE's 29% for the variable-speed pump:
- Florida: $852 × 0.29 = $247, a saving of about $605
- New Jersey: $442 × 0.29 = $128, a saving of about $314
- California: $1,840 × 0.29 = $534, a saving of about $1,306
The national average rate was 18.16 cents over the same months. Florida, Texas and Arizona all came in below it, so a national example flatters the saving in most of the Sunbelt. California, at 33.17 cents, is nearly double.
Payback, on a pump that still works
This is where a working pump and a dead one part ways.
When a pump dies, you're buying a pump anyway. Only the extra cost of variable speed has to earn itself back. When it still works, the whole price does.
Two mid-range variable-speed pumps were on sale at $1,609 and $1,649 at dealers in September 2026, down from $1,979 and $1,799. A variable-speed replacement motor was listed at $507 and $639. Against the savings above:
| Saving a year | Pump at $1,650 | Motor at $600 | |
|---|---|---|---|
| Florida | $605 | 2.7 years | 1 year |
| New Jersey | $314 | 5.3 seasons | 1.9 seasons |
| California | $1,306 | 1.3 years | Under 6 months |
DOE put the average life of an inground pump at about seven years. In Florida or California a new pump pays for itself early and then keeps paying. In New Jersey it takes most of the pump's life to break even, and a motor swap is the better bet.
Your equipment sets how slow you can go
The saving depends on hours at low speed. What stops you going lower is almost never the pump.
Hayward's manual says it plainly: "Equipment such as heaters, skimmers, and chlorinators require minimum flows to operate correctly." Here's what some common ones need:
- Gas heaters: 20 to 40 GPM for the Pentair MasterTemp and Max-E-Therm depending on size, 20 to 25 for the Hayward Universal H-Series, 30 for the Jandy JXi and 40 for the Raypak Digital 406A
- Heat pumps: 30 GPM for both the Hayward HeatPro and the Pentair UltraTemp
- Salt cells: 20 GPM for the Jandy TruClear, 25 for the Pentair IntelliChlor PLUS LT
- A tablet feeder: 20 GPM for the in-line VS version of the Jandy TruChlor, which carries inserts made for low flow
- A suction cleaner: Pentair's Rebel is set up for 28 GPM through its vacuum line
The low-speed test point in the ENERGY STAR data is about 31 GPM. That's already close to the floor for most of that list, so you run slow for filtering and speed up only for the jobs that need it. DOE's own model gave variable-speed pumps up to two hours a day at high speed.
A suction cleaner is the one that eats the saving. It wants flow for hours, not minutes. ENERGY STAR cites a PG&E study where a cleaner driven by the filter pump used 1,675 kWh a year, and a robotic cleaner used 197. If you're converting to save money and you run a suction cleaner daily, a robot is where the rest of the saving is.
Setting the actual schedule is its own job. How long to run the pump walks through it. The short version is that a variable-speed pump left on a high default saves almost nothing.
Motor or whole pump
A conversion doesn't have to mean new plumbing.
A variable-speed motor on the pump you have. Century's VGreen Evo is one example. Century sells it as a drop-in for a single-speed or two-speed motor, with no extra wiring or plumbing. It comes in square-flange and C-face versions from 1.30 to 2.25 total horsepower, and larger. Match the mount on your old motor. It runs on 115 or 230 volts and works out which on its own, but on 115 it tops out at 1.65 total horsepower. Century's warranty is 24 months from first use or 36 from manufacture, whichever comes first.
The motor only makes sense on a pump that's worth keeping. That means no cracks in the housing, sound threads at both ports and a strainer lid that still seals. You'll also want a new shaft seal fitted at the same time, because the pump has to come apart anyway.
The catch is the rebate. ENERGY STAR certifies complete pumps. None of its 423 listings is a replacement motor, and every rebate I checked names a certified pump. A motor swap costs about a third as much, and it gives the rebate up.
A whole new pump is the answer when the old one is tired, the wrong size, or you want the rebate. It's also a chance to fix a pump that was never sized properly in the first place. Sizing it is twenty minutes well spent before you buy. Where you buy matters too. Hayward and Pentair both cut the labor warranty on pumps bought online, and the Super Pump page spells out Hayward's version.
The electrical side of a conversion
A variable-speed pump is wired differently from the one it replaces. Four things change.
The timer comes out of the pump circuit. Hayward's manual covers this exact case. When a variable-speed pump replaces one that ran on a mechanical time clock, it gets wired straight to the power supply and the clock is bypassed. The breaker becomes the on-off switch, and the pump runs its own schedule. The old clock can then run a heater or booster pump during hours when the pump is fast enough to feed it. Pentair says the same for automation: the pump needs continuous power, straight from the breaker. The timer article has more on why.
It needs GFCI protection. Every manual I checked, from Pentair, Hayward and Jandy, says to connect only to a circuit protected by a GFCI. Hayward's cites the National Electrical Code for it. If the old pump's circuit doesn't have one, the conversion is when it gets one.
It has to be bonded. Hayward calls for solid copper bonding wire, No. 8 AWG or larger, on the lug on the motor. The bond wire moves to the new motor. It does not get left coiled on the pad.
Voltage matters more than it used to. Plenty of variable-speed pumps run on 115 or 230 volts, and some lose ground on the lower one. ENERGY STAR lists Hayward's TriStar VS 950 at 2.7 total horsepower on 230 volts and 1.5 on 115. Pentair rates the SuperFlo VST at a weighted energy factor of 9.0 on 230 and 7.3 on 115. If the pad can have 230, use it.
If you live where it freezes, check the freeze setting on day one. Federal rules require a pump with freeze protection to ship with it switched off, or set no higher than 40°F, one hour and half speed. That default may not be what you want. When a hard freeze is coming, run it continuously instead.
Rebates, and the catch in them
Rebates are real money, and they vary a lot. Here's what four utilities were offering when I checked in September 2026:
- Duke Energy, North Carolina: $900, for projects completed after January 1, 2025. A participating contractor has to install it and file the application.
- NHSaves, New Hampshire: $350, for a pump bought and installed in 2026. Apply within 90 days.
- Dominion Energy, South Carolina: $300. Apply within 90 days. Self-installs are allowed.
- PNM, New Mexico: $300, for purchases in 2026 while funds last.
Every one required an ENERGY STAR certified variable-speed pump, and not every variable-speed pump is certified. Of the two pumps I priced above, Pentair's SuperFlo VST is on ENERGY STAR's list and Hayward's MaxFlo VS 415 is not. Neither is the Super Pump VS 600. Check the exact model number before you buy, and use ENERGY STAR's rebate finder to see whether your utility has a rebate at all.
Duke's contractor rule is the easy one to miss. Buy the pump online to save a few hundred dollars, and the $900 is gone.
When I wouldn't convert a working pump
DOE's own numbers say variable speed isn't a win for everyone. Its 2017 analysis assumed you were buying a pump anyway. Even so, about one owner in ten with a typical inground pump would have come out behind over the pump's life. For small inground pumps it was nearer three in ten. For above-ground pumps it was about half.
On a working pump, here's where I'd wait:
- A short season and cheap power. At 15 cents a kWh, the same four-month season costs 15.2 kWh × 123 days × $0.15 = $280. Take 71% off and the saving is about $199 a year. A $1,650 pump needs more than eight seasons to earn that back, and DOE expects about seven.
- A pool that has to run fast anyway. If a suction cleaner or a water feature keeps the pump near full speed for hours, most of the saving isn't there.
- A small pump. A 1.1 THP single-speed already draws less, so there's less to save. And single-speed pumps that size can still be made until September 28, 2027.
- A pump with a year or two left. Let it die and buy the right thing then. Only the difference in price has to pay back.
Everywhere else, and especially anywhere with a long season, convert. A pump that runs year round in Florida, Arizona or California is the clearest case on this page.
Go deeperPump running cost calculatorYour wattage, your hours, your rate. See what your pump costs now and what the same water would cost slow. Go deeperThe variable-speed pumps worth shortlistingWhich to buy, once you've decided to convert. The deciding spec isn't energy savings.Frequently asked questions
Is it worth replacing a working single-speed pool pump with a variable-speed one?
For most inground pools open more than a few months a year, yes. DOE put a variable-speed pump's running cost at about 29% of a single-speed's. Where it gets marginal is a short season with cheap power, a small pump, or a pool that has to run fast for hours a day to drive a suction cleaner. Work out your own number before you buy.
Can I replace just the motor with a variable-speed motor?
Yes, if the pump itself is in good shape. Century's VGreen Evo, for one, is sold as a drop-in replacement for single-speed and two-speed motors, in square-flange and C-face versions. Two dealers listed the 1.65 THP model at $507 and $639 in September 2026. Fit a new shaft seal while the pump is apart, and know that it won't qualify for rebates that require an ENERGY STAR certified pump.
Are single-speed pool pumps banned?
Not the ones already installed. Federal rules cover what gets made. Since July 19, 2021, most new inground pumps have had to meet an efficiency bar set at variable-speed level, and since September 29, 2025, new pool pump motors from 1.15 to 5 total horsepower must be variable speed. Smaller motors, from 0.5 to 1.15, follow on September 28, 2027.
Does a variable-speed pool pump work on 115 volts?
Many do, but some give up capability on the lower voltage. ENERGY STAR lists Hayward's TriStar VS 950 at 2.7 total horsepower on 230 volts and 1.5 on 115. Pentair rates the SuperFlo VST at a weighted energy factor of 9.0 on 230 volts and 7.3 on 115. If the pad can have 230, that's the better way to run it.
Do I need an electrician to convert to a variable-speed pump?
Pentair, Hayward and Jandy all require a circuit with GFCI protection, and their manuals call for the pump to be bonded to the pool's bonding grid. If your old pump ran through a mechanical timer, the new one normally gets wired straight to the breaker instead. That's electrical work, and some utilities also require a participating contractor before they'll pay a rebate.
