Things to know when buying a swimming pool pump. Types of pool pumps, advantages, and disadvantages, how do pumps work, and features to look for. Compare single-speed vs. dual-speed vs. variable speed pumps.
The main job of a pool pump is to push the water in your pool through the filtration system and heater, so the water is cleared of any debris, heated and decontaminated, then returned to your pool clean, warm, and pristine.
There are strict guidelines around pool requirements published in the American National Standard for residential in-ground pools; however, there are presently no Canadian swimming pool laws. Also, there are very few Provincial laws concerning private pools. Only Quebec, New Brunswick, and Manitoba have passed regulations in this area. Your local area building department will guide you on permits and specific local requirements.
There are three types of swimming pool pumps available for homeowners:
Single-speed pumps have been the standard for years, and when switched on, they run at a constant rate until you switch them off again. These swimming pool pumps are cheap to buy, noisy to operate, and energy inefficient. Some models could cost you as much as $2000 a year to run!
A two-speed pool pump is a development of the basic single-speed pump with the same induction motor. It can run at a slower speed, which is more energy-efficient than continually running at high speed.
Usually, the low speed is for 24/7 operation, and the higher setting is when you’re cleaning the pool or running a heater, which generally requires a higher flow rate to operate correctly.
Variable speed pumps are entirely different from the single- and dual-types. They use the same permanent magnetic motor technology used in electric vehicles, enabling you to select a precise flow rate for your pool, thus saving energy and money.
Variable speed pumps are better in every way. They are quiet because they use a TEFC motor. Their sealed design keeps moisture out and protects them from ambient conditions, which is especially important in high humidity or salt areas, for example, if you live close to the ocean. They don’t rust or deteriorate in the same way a regular pump does.
Variable speed swimming pool pumps run cooler with low vibration. They use the latest digital technology, which allows self-diagnosis of any faults, so they will flag up when a problem occurs. It means you can deal with it before it becomes a more serious and potentially expensive issue.
Because of their unique sealed design, variable pumps last longer, even in very wet conditions. The expert view is they may last several times longer than traditional single-speed or two-speed pumps.
You can manage the pump accurately by selecting your settings, and they have in-built, preset programs which you can override and change to suit your own needs. Most studies have found these pumps are over 90% more efficient than the basic single-speed units we’ve lived with for so long. The average monthly running cost is between $20 and $30.
A variable speed pump could save you around $1000 per year, and they offer you a choice between economy and efficiency. If you select the economy mode, you could save approximately 75% of your pool power costs; however, the downside is the pool may not be quite as clean as you wish.
On the other hand, if you choose maximum efficiency and run your pump at a higher speed, the pool will be pristine, but your power savings will be less at around 40 – 50%.
Whichever you choose, you still win.
The most critical factor in selecting a swimming pool pump is the turnover rate, which is the actual time it takes to move your total pool water volume once through the cleaning/heating/filtration cycle.
The way pool pumps are rated, apart from their horsepower, is by the total gallons of water per minute (GPM) they can handle. Aim to match the required minimum turnover by using the least amount of energy to achieve it.
There is confusion between the horsepower of a pump and its efficiency. If you choose a large horsepower pump, it will cost more to buy and run. Instead, it would be best if you did some easy math, then you will get the highest efficiency possible by purchasing the correct size pump for your pool.
Finding your pool volume is easy. If you built the pool, you probably already know the volume of water that’s in it. If not, don’t worry; there are several volume calculators to help you. Or you could ask one of your smart children!
For the rectangular pools, the volume is calculated as Length x Width x Depth.
For the circular pools, the volume is calculated as Radius x Radius x 3.14 x Depth.
You will have to calculate the flow rate, which is the amount of water that passes through the pump in a given period.
Your pump has to recycle all the water in your pool every 24 hours to keep it clean and safe.
To work out the minimum flow rate that you need, divide the volume of your pool in gallons by the number of minutes in each day (60min*24h=1440).
For example, if your pool volume is 24,000 gallons, then:
24,000 / 1440 = 16.7 GPM, which is the minimum rate you need to achieve a turnover of 24,000 gallons in 24 hours.
Also, calculate the rate which would turn the pool volume over in six hours or 360 minutes (6*60). This is the recommended maximum rate by the California Energy Commission (CEC) and agreed by the Association of Pool and Spa Professionals (APSP) to help obtain maximum energy efficiency from pool pumps.
The six-hour GPM rate should never exceed the rate that your filtration system can handle. This information is on a label on the filtration unit. If you exceed the recommended GPM rating, you will potentially overheat and damage your pump and the filter unit.
To calculate the maximum rate, divide the total volume of the pool by 360. If your pool holds less than 13,000 gallons, the pump must have a GPM rate lower than 36 GPM.
For example, if your pool volume is 24,000 gallons then:
24,000 / 360 = 66.7 GPM, which makes the maximum flow rate 66.7 Gallons Per Minute.
Have a look at the US Department of Energy information here.
(Use an online calculator and save yourself some brain pain and time!).
Plumbing is a critical factor, especially with older installations where the pipe sizes may be too small. It can adversely affect your pump’s ability to handle the volume of water.
Smaller diameters like 1.5” pipe are often unable to cope with large, powerful pumps. If you do have small bore pipes, consult the pump manufacturer to find the best solution.
Look for Energy Star Certified models whenever possible.
Check out the warranty offered. Favor longer guarantee periods and companies with the best reviews. Online retailer reviews can be excellent sources of information.
Make sure you can figure how to set the pump up, so you don’t need to call a professional to change the speed. Often with hi-tech equipment, it can be over-complicated. Select a pump that allows you to change the settings easily and quickly.
Learn how to achieve the maximum benefits from your variable pump. It is intelligent and offers the opportunity for you to maximize energy savings that single or two-speed pumps can’t offer. Don’t fit it and forget it; you will lose out.
Seek help from a pool and plumbing professional, you have some complex decisions to make, and it’s worth being prepared. You want to avoid making an expensive mistake. If you know the facts, you can’t go wrong.
The foreseeable future is with variable speed pool pumps. Regulations in California, for example, are changing in 2021 when they will prescribe minimum efficiency regulations for all pool pumps.
They are encouraging pool owners to install timers and operate pumps during off-peak periods only. The plan is to restrict pump operation to two hours a day in winter and four hours in summer.
The US Department of Energy will make it compulsory for all pump manufacturers to observe the new regulations and only produce pumps that comply with the latest energy-efficiency regulations.
Right now, the only pumps meeting this benchmark are variable speed pumps.
One final thought is if you are thinking of changing your pool pump soon, it may be a good idea to buy and upgrade to a variable speed pump and get ahead of the legislation if for no other reason than you will also save a significant amount in your energy bills going forward. Now that can’t be bad, can it?