Pentair SuperFlo 1/2 Speed Test (1750 RPM)
The Pentair SuperFlo variable speed pump has a 1.5 horsepower motor which is a very common size for swimming pool pump motors. Although horsepower ratings really are a poor metric with which to compare pool pumps the reality is that this will be the first comparable that pool owners look to when trying to find a replacement pump. If they see a 1.5 horsepower pump on their pool that is probably what they will replace it with, without first considering whether it should have been there or not in the first place...I mean it did just fail after all. As a pool professional I encounter dozens of pool owners every year who complain about their pool pump failing earlier than it should have. In a great many (the majority) of those cases I am able to identify deficiencies within the plumbing system that undoubtedly contributed to the early failure of the pump. If you would like to see some examples of early pool pump failures then you can read this article about why your pool pump failed early.
Understanding that horsepower is not what you should look at when comparing pool pumps, or determining your filtration schedule, what should you be looking at? The answer to this, primarily, is flow rate. Flow rate is the defining factor for how much filtration your pool gets every day. The rule is that your pool water should all be filtered every day, and this takes four turnovers of the pool volume every 24 hours in order to achieve (98% of all water filtered at least once). Even if you like to cut your filtration short of this established standard of care for pool water filtration, you should still be making that decision based on flow rates. The real reason that pool owners do not do this more, the only reason really, is simply because residential swimming pool systems lack the ability to display flow to the pool operator. In the commercial world of swimming pools flow meters are actually required, but not so in residential pools. This is something that is almost certainly going to change about the residential pool industry once variable speed pumps become required by law in 2021. For more information you can read this article about why don't more pools have flow meters?
For now, the average pool owner does not know how much flow they have in their pool system at any given time, and so they are unable to answer the critically important question about how much (volume) they are filtering their pool every day. This is also not the type of question that you can just go hunting on the internet for since pool flow rates, system pressure, resistance to flow, system efficiency...all of these things will be unique to your pool and your pool only. This means that aside from inviting an industry expert onto your property to evaluate your pool system and provide a feedback report, or installing a flow meter, the best you can hope to do is make an educated guess as to your flow rates.
How Much Flow From 1/2 RPM
I designed the Swimming Pool Steve Test Lab for testing pool pump flow rates and electrical efficiency in a way that would makes it easy to see and understand. Each pool system will be different however this will provide a starting point for making an educated guess as to how much flow your system is able to generate. Of course I definitely recommend that all pool owners order and install a flow meter. However without one you might be wondering how much volume your pump is able to move. This test involves a 1.5 horsepower pump. In this case the pump is a variable speed pump, the Pentair SuperFlo 342001, which is a very popular entry level variable speed pump.
The test parameters for this system involve very little resistance to flow, which is to say you will never find a real world swimming pool where this pump is able to move more water than what you see here. Only less water. This establishes a good baseline with which to form an educated guess as to the flow rates that your pool has with similar settings, specifically 1750 RPM.
1750 RPM - 1750 RPM is a very significant number as this represents approximately half speed for your motor. 3450 RPM is the standard speed for a pool pump electric motor, and if you have a single speed pump that is the RPM that it would be. If you had a dual speed pump, or a "two speed pump" then the low speed setting would be equivalent to half speed, or 1750 RPM.
For this reason the information gained from testing this pump at half speed will be useful to many different pool owners. If you have a 1.5 horsepower pump of another brand then this information should be at least comparable. If you have a two speed pump you will be able to estimate how much volume you might be getting on your low speed setting. However most pool owners will find this information useful because they have purchased a new variable speed pump and are just now learning about and experimenting with motor speeds. In order to get the most out of your investment in a new variable speed pump you will need to know some additional information:
How to program a variable speed pump schedule
How to program a Pentair SuperFlo for maximum electrical savings
So assuming you have a variable speed pump or a dual speed pump, and it is in the range of 1.5 horsepower, then you can use the following flow and power consumption information to help determine your top end expectations. Again, since this is a bench test on a system with almost no resistance to flow this means the pump will produce less flow if this exact test were recreated on your specific pool. These numbers will give you an idea of what your "best case scenario" flow rates might look like. I think a small allowance for real world efficiency loss to the tune of 10% less flow sounds reasonable to me.
Pump: Pentair SuperFlo 342001
Motor speed: 1750
Flow rate: 42 GPM (2520 GPH)
Electrical consumption: 1.8A / 367W (@240V)
From this information what we can see at a glance is that this pump (and all pumps) use very little power when running at lower RPM speeds. Even though the motor on this pump could be turned down much further than this 1750 test, already the power savings are significant. If you want to see what the power consumption and flow rates look like for this pump at higher speeds then you can check out this bench test, flow rate and power consumption analysis series I made using this pump here: Pentair SuperFlo power consumption test.
From this testing information we can also see that at 42 gallons per minute this pump is still moving an appreciable amount of water despite using very little power overall. At these flow rates this pump would move 2520 gallons per hour, just over 10,000 gallons in four hours, 20,160 gallons in eight hours, 30,240 gallons over a 12 hour run time, and just under 60,500 gallons if you ran your pump around the clock, 24 hours per day like this.
At 60,500 gallons in a 24 hour period you might be wondering how much this would cost to do. The electrical rates you pay change based on where you are, and also the time of day that you are using the power as most areas have peak and off-peak electricity rates now. Using a nationwide average of 13.3 cents per kWh (kilowatt hour) then you could estimate that this pump would use 8.8 kW after 24 hours of running (367W x 24). This means your cost to run this pump for 24 hours like this would be $1.14 cents. That is a very reasonable amount of electricity, and cost, for that volume of water filtration. Especially when you consider that on high speed (3450 RPM) the power consumption is not double, but 2240 Watts per hour, versus the 367 Watts per hour for the half RPM operation. Really incredible savings when you take the time to understand how all of this works and actually see the flow rates and savings in action.
I really hope you found this information helpful, and if so please be sure to subscribe to the Swimming Pool Steve YouTube Channel to see more pump testing videos (and other swimming pool and spa related videos) in the future.
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