Don’t Buy a Two-Speed Pool Pump

I keep asking myself, “am I missing something?” Why are pool builders still building new pools with two-speed pumps? If you are buying a new pool, I can’t say it any other way: Don’t Buy a Two-Speed Pump!

The basic idea behind two-speed pumps is good. You can run the pump at a lower speed, saving electricity. Unfortunately, there are many downsides:

  • These pumps require a two-speed timer or control system.
  • They are rarely set up properly to actually save you money.
  • The flow rate is often not enough to maintain good pool chemistry and sanitation without operation at high speed at least some time each day.
  • The low speed flow rate may not be enough for pool heaters to operate effectively, efficiently, or at all.
  • The low speed may not allow operation of salt chlorine generators.
  • The high speed is every bit as loud and inefficient as a single speed pump.

Two-Speed Pumps Make No Economic Sense

The cost of a two speed pump plus a two-speed controller is often the same as a variable speed pump. In fact, it may be less.

I just checked the prices of a Jandy FloPro 1.5 HP two-speed pump and an Intermatic PE153 digital timer at my local supplier. The cost is about $20 less than a Pentair Superflo VS 1.5 HP Variable Speed pump. But when you consider that the Pentair pump is easier to install with less wiring than the Jandy/Intermatic combination, there is no cost advantage to the two-speed option.

I did the same check with other brands, and in just about every case there is a suitable variable speed option that costs a similar amount.

Sure, you might argue that when it comes to replacement, the cost of replacing the two-speed pump will be less because you need not replace the timer. However, when you consider the expected service life of the variable speed pump and the operation costs, the cost per year of ownership is actually much less for the variable speed option.

In fact, the electricity savings from a variable speed pump can actually pay for the pump over it’s lifetime!

Why Variable Speed Pumps Are A Better Option

The Pentair Superflo VS 1.5HP Variable Speed Pump is a great alternative to a two-speed pump.
The Pentair Superflo VS 1.5HP Variable Speed Pump is a great alternative to a two-speed pump.

Cost Savings and Efficiency

A variable speed pump like the Pentair Superflo has an inherently more efficient permanent magnet brushless motor. That means at the same flow rate the pump will require less electricity. The energy savings from a variable speed pump are undeniable.

But where variable speed pumps really shine in terms of energy savings is when you turn down the flow. At half the motor speed the pump will consume 1/4th the power! The ideal scenario is to run your pump for a much longer time at a much lower speed, attaining the same turnover in your pool each day at a much lower operating cost. In fact, many people run their variable speed pump twice as long as a single speed pump, or even 24 hours a day in some cases.

Pool Pump Automation

Setting aside energy savings and initial costs for a moment, there are other reasons why variable speed pumps are an excellent choice. Another reason not to buy a two-speed pump is that they require two-speed relays when connecting them to automation systems, and some automation systems are not capable of two-speed pump control.

For example, let’s say you have a solar pool heater or gas heater. You will invariably need to run a two-speed pump on high speed when operating the solar panels. That means you need a control system to change the pump speed. Basic solar controllers like the Pentair SolarTouch or Hayward GL-235 do not have two-speed pump control. You would have to install a more expensive controller with a lot of bells and whistles just to control the two-speed pump. If you have existing automation, you would need to install an expensive and relatively complicated two-speed relay.

Variable speed pump take that complexity away. Most of the good ones can be controlled with a low voltage digital or analog control cable, especially if matching controller/pump brands. Workarounds and interfaces exist when mixing different brands. It is wise to make sure you are installing compatible pumps and controls, however.

The same thing applies to traditional heaters – they usually need a higher speed for proper operation.

Optimizing for Features

Aside from getting the proper speed for heaters, pool features like waterfalls, spillovers, jets, and bubblers all have ideal flow rates. With a two-speed pump you have only two choices. With a variable speed pump you can “dial in” the perfect speed that optimizes you water features while minimizing operation cost.

I recently went to a home with a new pool where the owner inexplicably had three pumps installed. The main pump was a two-speed. One pump was a single speed pump used solely to make deck jets shoot fountains of water arcing into the pool. The pump was way oversized and the jets would spray through the pool screen unless valves were closed off to reduce the flow. This is a huge waste of energy.

The whole pool could have been designed with a single variable speed pump, automated to change speed based on the features in use. The cost of an automated variable speed pump would have been less than the three pumps on timers with manual control. With a variable speed pump you get a huge amount of control over pump speed and flow.

Choosing the Right Variable Speed Pump

It should be obvious why you don’t want to buy a two-speed pump, but how do you choose the right variable speed pump? There are a few factors I suggest:

  • Buy a popular pool brand. The big three manufacturers (Pentair, Hayward, and Jandy) have much more experience and the popularity of their pumps have made them clearly the best.
  • Don’t undersize your variable speed pump. Because you can operate the pump at any speed, don’t hesitate to oversize your pump and run it at a slower speed. This will reduce noise drastically, not cost any more to operate, and in theory it will last longer running at a lower speed. Sure, it costs more up front, but it’s well worth it in my opinion. You can get a 3HP flagship for just a few hundred more than a 1.5HP from the same brand. You will also have more fine tuned flexibility to run your heaters and features. You can limit the pump motor speed to accommodate your maximum flow rate needs. We actually currently recommend the Pentair Intelliflo 2 VST pump, which is 3HP max, over the 1.5HP Pentair Superflo.
  • Consider your current and potential future automation needs. If you later buy a new heater (solar, electric, or gas), you will need to automate your pump speeds to balance heating performance with energy savings.

Final Word On Two-Speed Pumps

We often find ourselves at odds with pool builders regarding two-speed pumps. For most pools, single-speed pumps are no longer an option due to energy efficiency building codes. Two-speed pumps were the first options available to replace single-speed pumps, and were once the only cost effective option. Many pool builders switched to two-speed pumps because they represented an easy switch with similar calculations, wiring, and performance characteristics.

Early variable speed pumps had some performance and longevity issues, giving them a bad reputation with some pool builders. With experience, variable speed pump manufacturers are now offering unparalleled warranties on excellent products.  Some pool builders are still skeptical. But the clear success by the big three manufacturers and new entrants into the market have made variable speed pumps the norm for most pool builders today.

In the cutthroat business of pool building, cost matters. Remaining cost competitive was once a big reason to go with the cheapest pump possible and save budgetary dollars for flashy pool features that sell pools. The pool pump is the heart of your system, and you should consider spending a little more to get the best option that maximizes pool performance while minimizing operating costs.

Today, it’s effectively the same initial price to install a quality variable speed pump, so don’t buy a two-speed pump!


  • Comment (2)
  • blank Jeff Roberts says:

    sounds great– except my very expensive hayward variable speed pump will not pump water through my roof mounted solar heater at anything below 2600 RPM. Using the pump at any lower speed and it won’t push any water through the system at all. it was great until i got the solar heater– then it is useless to spend that much money on a pump that I can;t use except at one speed.

    • blank Jason Szumlanski says:

      I do not know what speed you run your pool without solar panels, but 2,600 RPM should still provide substantial savings over the full 3,450 RPM maximum speed. The energy savings are the cube of the speed change. For example, a doubling of speed results in 8x the energy required. By running your pump at 75% (2600/3450) your pump will only require 42% of the energy compared to its full run speed (approximately).

      When you use a variable speed pump with solar panels, yes a solar controller is necessary to control pump speeds. Often this can be handled by existing pool automation if present. If you do not have automation, you would need to run your pump at the “solar speed” at all times when your manual solar heating valve is on.

      The issue can be alleviated by purchasing solar panels with a low resistance to flow, like the iSwim panel, and using 2 inch inside diameter plumbing. There are solar panels on the market that have a lot of backpressure, meaning you need a higher pump speed to achieve the same flow rate. That’s not good when you have a variable speed pump.

      It’s true that solar pool heating is more expensive if you do not have existing automation because you may have to purchase a solar controller to keep your variable speed efficient. This is one argument with going a different direction, using a heat pump and investing in solar electric panels to offset the energy used. We call this strategy Solar Hybrid Electric Pool Heating.

  • blank Jeff R says:
    Your comment is awaiting moderation. This is a preview; your comment will be visible after it has been approved.
    Sounds great. Unless you have a solar pool heater. Anything under 2000 RPM and my high end tristar won’t pump to the roof. So I can’t take advantage of the slower speeds. And some will say I have to buy a controller. By the time I pay for a high speed pump and controller and all the things required for that.. The cost saving is lost compared to a simple 2 speed pump. Now I agree that before i installed my heater the variable speed did save money.

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