Quick answer: a variable speed pool pump saves money because pump power drops much faster than pump speed. Run a pump at half speed and it uses roughly one eighth of the power. Pentair says variable speed pumps can cut pump energy costs by up to 90 percent compared with a single speed pump. For many pool owners that adds up to hundreds of dollars a year.
Here is how the savings work, a simple example you can redo with your own numbers, the federal rule that changed replacement pumps, and the speed settings that get the most out of one.
Why slower is so much cheaper
Pumps follow what engineers call the affinity laws. Flow goes down in a straight line with speed, but power goes down with the cube of speed:
- Full speed: 100 percent of the power
- Three quarter speed: about 42 percent of the power
- Half speed: about 12.5 percent of the power
So running at half speed for twice as long moves the same water with about a quarter of the energy. Pentair puts it simply: cut the pump speed in half and you cut consumption by about 87 percent.
A single speed pump has one setting: full speed. A variable speed pump lets you run slow for daily filtering and only go fast when you need it.
Savings example
Here is a simple example. Actual watts depend on your pump, plumbing and filter, and many variable speed pumps show live watts on the display so you can check yours.
| Single speed 1.5 HP | Variable speed | |
|---|---|---|
| Schedule | 8 hours at full speed | 2 hours high, 10 hours low |
| Power used | About 1,700 watts | About 1,500 watts high, 200 watts low |
| Energy per day | About 13.6 kWh | About 5 kWh |
| Cost per day at $0.30/kWh | About $4.08 | About $1.50 |
| Cost per year, daily use | About $1,490 | About $550 |
In this example the variable speed pump saves about $940 a year while running 4 more hours a day. The longer, slower run also filters better.
Do the math for your pool: watts x hours ÷ 1,000 = kWh per day. Multiply by your electric rate from your utility bill.
The 2021 federal pool pump rule
Since July 19, 2021, new pool pumps made for or imported into the U.S. must meet U.S. Department of Energy efficiency standards. The rule covers dedicated purpose pool pumps up to about 5 total horsepower. According to Jandy, most variable speed pumps meet the standard, while most single and two speed pumps of 1 HP or more do not.
In practice, that means when your old single speed pump fails, its replacement is most likely a variable speed pump. Some pumps are exempt, such as certain waterfall pumps and pumps with 3-phase motors.
Speed settings that save the most
Every pool is different, but these are common starting points:
- Daily filtering: low speed for many hours. This is where most of the savings come from.
- Skimming: a medium speed for an hour or two so leaves reach the skimmer.
- Pool cleaner, heater, spa jets and waterfalls: higher speeds, only for the time you need them.
- Heaters and salt cells: both need a minimum flow to run. Set the speed high enough that they turn on and stay on, then no higher.
Pentair also points out that running longer at low speed helps filters trap more dirt and helps chlorinators and chemical feeders work better.
Choosing a variable speed pump
- Match the horsepower class to your pool and plumbing. A 1.5 HP class pump suits many average backyard pools. Larger pools, spas, waterfalls and long pipe runs often need a 2.7 to 3 HP class pump.
- Check voltage. Many pumps run on 115V or 230V. Some larger pumps are 230V only.
- Check the port size so the pump fits your plumbing.
- Think about control. Most variable speed pumps have a built-in timer and speed presets, and many can also connect to your automation system or an app.
Popular variable speed pumps
- Pentair IntelliFlo3 VSF 1.5 HP (011065)
- Pentair IntelliFlo3 VSF 3.0 HP (011075)
- Hayward MaxFlo VS 1.5 HP (W3SP2303VSP)
- Hayward TriStar VS 2.7 HP (W3SP3206VSP)
See all options in our variable speed pool pumps and Pentair pumps collections. Comparing Pentair models? Read IntelliFlo VS+SVRS vs IntelliFlo3, and if you already own one, see how to reset an IntelliFlo3.
Variable speed pump FAQ
Is a variable speed pool pump worth it?
For most pools, yes. A pool pump often runs every day for most of the year, so cutting its power use by half or more usually pays back the extra cost within a few seasons. Many utilities also offer rebates, so check with yours before you buy.
How many hours a day should a variable speed pump run?
Most owners run 8 to 12 hours or more at low speed, enough to turn over the full pool volume at least once a day. Because low speed uses so little power, running longer usually costs less than a short run at high speed.
Can I run a variable speed pump 24 hours a day?
You can, at a low speed. Some owners do this for the best filtering. Watch your energy use on the pump display to find the sweet spot.
Will a variable speed pump work with my heater and salt system?
Yes. Just set the speed high enough during heating and chlorinating that the heater and salt cell see their minimum flow. Many automation systems can raise the speed automatically when the heater turns on.
Can I replace my single speed pump with a variable speed pump?
In most cases, yes. It usually connects to the same plumbing and power. Match the horsepower class and port size, and confirm the voltage.