Pump Basics
The pool pump market was turned upside down when the US Department of Energy (DOE) implemented Federal Energy Efficiency regulations, as of July 19, 2021, on Dedicated Purpose Pool pumps (DPPP). For more about that read Pump DOE Regulations.
It used to be that pool pumps were selected based on the pump horsepower to fit the size of the pool and equipment. You were advised a pump which is too large for the plumbing and equipment could cause damage to the filter and other components and will use more energy than a smaller pump. Turnover times of the pool water used to be discussed although we now know that turnover does not matter.
Since the US DOE regulations came into effect almost all pool pumps of 1.1 THP or more are variable speed pumps. There are some exceptions for low HP, high HP, and specialty pumps. And if you are not in the US then single speed or 2-speed pumps may still be available.
What Pump Should You Buy?
It is nearly always advantageous to go with a larger Total Horse Power (THP) VS pump in a pump family for both lower noise and greater electrical energy efficiency unless electrical cost does not matter to you.
A Variable Speed Pump is a variable HP pump. So the concerns about a high HP pump damaging equipment are no longer valid. You run the VS pump at the speed and HP most suitable for your pump and equipment.
Variable speed pumps are more complex then single speed or 2-speed pumps with electronic control panels to set run times and speeds. Some VS control panels can be very rudimentary while others can have sophisticated controls. If you will not have an automation controller controlling your VS pump you should review the pump Owners Manual and understand the controls of a pump you are considering.
Pool automation expands the utility and efficiency of a variable speed pump by setting the optimum pump speed for filtering, skimming, cleaning, and running spa jets and water features during the day. If you have an automation controller or may get one in the future you must ensure the automation and pump controls are compatible. Usually that means the automation and pump should be from the same manufacturer and even then manufactures may have incompatibilities between their products. Check manufacturer websites and our Wiki pages for the specific automation and pumps you are considering.
There are still some 1.1THP single speed pumps that are DOE compliant but not available in all States due to separate State pump regulations (CA, and maybe others). For some small pools, pumped water features, and other situations, single speed pumps still make sense. They can be lower cost and simpler in operation and maintenance then VS pumps. Pentair, Jandy, Hayward, and others all have single speed low HP DOE compliant pumps.
What Brand Pool Pump?
At it's heart, a pump is a commodity product where they are all the same in they move water. If you want to move water in a simple pool then a low cost pump that is disposable when it fails may be all you need.
Pentair, Hayward, and Jandy are the big three equipment manufactures. They offer you support and warranties if you go through their authorized dealer channels and compatibility with their automation products. They have multiple pump families with various features and horsepowers for every price point.
Waterway, Circupool, B+D, and others have VS pool pumps with basic features and maybe rudimentary automation interfaces using relays versus RS-485 data comm link. These pumps are at a lower price point then the major manufactures and are attractive to the DIY pool owner who does not care about warranty and support.
There are many low cost Chinese manufactured pumps being sold online. They may be appropriate for the price sensitive pool owner who does not care about warranty or support or spare parts for repairs. Those pumps are probably disposable when they fail.
Choosing Among Pump Families
So now we have you looking at VS pumps from one of the major manufactures and they have a few different families of pumps. What are the major differences and how do you choose which is suitable for your pool?
Before the US DOE caused all the pump technical and marketing changes pool pumps could be classified as:
- High head pumps for complex equipment with spas, multiple heaters, solar panels, IFCS
- Medium head pumps for basic pools with a filter, SWG, and maybe a heater
- Low head pumps for water features and fountains
No, we are not going to get you to calculate the "head" of your pool plumbing. The specific value is not needed. But you can eyeball a pool setup and see if it is a high, medium, or low head setup. Head being the force/resistance working against the pump as it pushes water through your pipes. Filters, heaters, spa jets, In Floor Cleaning systems (IFCS), solar panels, all create resistance and add to the plumbing head and can make a high head pump more suitable then a medium head pump.
Manufactures rarely label if a pump is high, medium or low head in their sell sheets or manuals. However they have organized their pump product line families into those categories:
- Top of the line 2.7-3+THP VS pumps are high head pumps suitable for pools with heaters, spa jets, IFCS, or solar panels
- 1.5THP VS pumps are typically medium head pumps for basic pools
- low head pumps are labeled "Water Feature Pumps" and for simple pools with a basic skimmer, filter, return setup.
There are not hard cutoffs as to which pump should be used for which environment. However, an underpowered pump can leave you with disappointing flows while an overpowered VS pump speed can always be lowered to give you the flow you want. That is why, in general, we recommend getting the 2.7-3HP pumps versus the 1.5HP pumps.
Replacing an Old Pump
You are not new to pools and you got here because your old single speed or 2-speed pump failed. You have not shopped for a pool pump in many years and the pool pump market changed with the 2021 US DOE regulations.
If your motor failed and the front wet end of your pump is in good condition you can replace the motor. Replacement motors are still available for many single speed and 2-speed pumps as well as variable speed replacement motors. However, look at what your electrical cost is to run your pump.
A 1HP pump uses about 1KW or electricity per hour, a 1.5HP pump uses 1.5KW/hour, and a 2HP pump uses 2KW/hour. Depending on your daily pump runtime and your electrical cost/KW hour you can calculate approximately what your pump is costing you to run.
Jandy Pool Pump Savings Calculator, Pentair Pool Pump Calculator, and Hayward Pump Energy Calculator help you compare a single speed pump with a VS pump.
Replacing a failed pump with a VS pump instead of replacing the motor can have a payback in a few years based on your pump runtime, cost/KWH, and the electrical savings.
Past The Pump Basics
For the analytical types who want to look more into pump specifications, when selecting a pool pump you want to look at the pump curve, which shows how the flow varies with pressure (head).
When choosing a pump, the desired flow is used to calculate how much resistance (pressure, head or head loss) will be generated by the system at that flow rate.[1]
The point on the pump curve where the pressure and flow intersect is called the operating point. The operating point should be near the middle of the pump curve. Pumps do not perform well near the ends of their curves.
For example, if a WhisperFlo pump (high head) is used on a fountain (low head application), the pump will run too far to the right on its curve, which can cause multiple problems like noise, maybe cavitation and it's very inefficient. A properly chosen pump, like a fountain pump, will be quieter and more efficient.
When choosing a pump, you should look at the maximum head (given in feet) and the maximum flow as shown by the curve. Then choose a pump that will operate within the limits but not near the limits.
A properly designed system should generally not need high flow or create high head. High head can be created by rooftop solar or in-floor cleaner systems.
The maximum flow usually needed for a residential pool will usually be due to a big gas heater (400,000 btu/hr) that might require about 40 to 50 gpm. Other than that, the flow can usually be pretty low (about 20 gpm).
A two speed or variable speed pump that runs on low except during times where higher flow or pressure is required can be a good choice.
Any new pool should use a variable speed pump.
If a single speed pump is used, it should be a maximum of 1.0 total hp.
Other Resources
- Equipment Pad Best Practices discusses plumbing design and flow rates.
- Determine Pump Runtime discusses the tasks you run your pump to accomplish.
