Variable Speed Pump vs Single Speed: A Comparison

Good circulation is crucial to properly maintaining a pool, which is why a variable speed pump can be one of your best pool investments.

Circulation ties directly into the pump operation; mainly the flow rate of the water and time of circulation. In addition, the more times your water turns over in a day — how many times the full volume of water in the pool passes through the circulation system — the better the pool the circulation will be.

There are two main types of pumps in the pool space, single speed and variable speed pumps. The difference between the two is that variable speed pumps allow you to adjust the flow rate of water through the circulation system, while single speed pumps only have one speed. Typically this single speed correlates to the max operating speed of variable speed pumps.

With a variable speed pump a pool owner can circulate their water at lower flow rates for a more prolonged period of the day without added energy consumption. This study by the National Renewable Energy Laboratory confirms that variable speed pumps are significantly more energy efficient than single speed pumps.

For a quick comparison, let’s compare the energy cost of a single speed pump running for 8 hours a day at 3450 rpm, to a variable speed pump running for 24 hours a day at 2400 rpm.

VSP-blog-table
Source: “Measure Guideline: Replacing Single-Speed Pool Pumps with Variable Speed Pumps for Energy Savings,” U.S. Department of Energy

VSP-blog-graph-1

 

VSP-blog-graph-2As you can see, the energy cost is almost identical; however, the variable speed pump turns the water over more than twice as often. For this reason, many states offer energy rebates for buying variable speed pumps.

No matter what type of pool sanitation the pool is using, I will always recommend continuous (24 hour circulation) for three reasons:

1. It helps to prevent stagnant water that algae and bacteria like to grow in.

2. It helps to promote filtration, which removes big particulates that bacteria and algae like to grow on and eat.

3. It allows the sanitation system to treat the water more often which is crucial for UV, ozone and our Clear Comfort systems. Furthermore, it is beneficial for salt systems because you are able to turn the salt production down which reduces the wear and tear on the salt cell. It is also helpful for chlorine/bromine injectors and tab feeders because you are also able to introduce less sanitizer which will allow for a more stable sanitizer concentration in your pool.

Although single speed pumps are a bit cheaper than a variable speed pump, the benefits of water turnover, extended filtration and prolonged sanitation times will make maintaining your pool easier. Furthermore, the energy savings that a variable speed pump offers over a single speed pump will pay for the initial price difference within several years. So here is my question to you: Why would you settle for a pump that can only do half the job that a variable speed pump can do?


Comments

12 responses to “Variable Speed Pump vs Single Speed: A Comparison”

  1. Steve Menke Avatar
    Steve Menke

    Good article. I am interested in the application for south Florida. Also how does variable speed affect suction cleaners such as the zodiac g3

  2. Frank Gischler Avatar
    Frank Gischler

    very informative, however I have several questions.
    Can you respond to those?

    1. Hi Frank,

      Thank you for reaching out. Please feel free to call me at 720-575-5581 and I’d be happy to answer any questions you may have.

  3. Robert Harrop Avatar
    Robert Harrop

    I have the in-pool popups system for cleaning my pool. Can I use a variable speed pump with that type of system.

    My guess would be that I would need a single speed pump for my system to operate properly.

  4. Tracey Gameiro Avatar
    Tracey Gameiro

    what about putting a single speed pump on a timer? Would that make its energy savings comparable to a variable pump and be half the cost for the unit?

  5. Your article states there are no energy savings when comparing 8 hours per day single speed v 24 hours variable speed but in your conclusion you state energy savings will offset the cost. Can you clarify? Also, won’t a pump running 24 hours per day wear out sooner than one running 8 hours?

  6. Every Pool store installation guy (we went through 4 IntelliFlo VS in 8 years with surge protection etc) advised to get single speed pump instead. Since vs pumps are more prone to break (especially here in lightening haven Florida) and most definitely cost more money.

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